POROUS AND CONTINUOUS COMPOSITE MEMBRANE AND METHOD OF PREPARING THE SAME Technical Field The present invention relates to a porous and continuous composite membrane and a method of manufacturing the same. More specifically, the invention relates to a porous and continuous composite membrane and a method of manufacturing the same, in which fine particles having a size of a few nanometers to a few micrometers are dispersed uniformly to thereby enhance the physical property of the membrane. In particular, the invention relates to a battery (cell) including a porous and continuous membrane in which solid particles having a size of a few nanometers to a few micrometers are dispersed uniformly in a plurality of polymer nano-fibers of which contacting points are fusion-bonded, or the dispersed solid particles are dissolved, the porous and continuous membrane being used as a filtering membrane, an electrolyte membrane, an electrode layer or a catalyst layer, when it is applied to batteries.

Background Art A porous and continuous composite membrane, which is prepared by dispersing an excessive amount of particles in a

polymer material, is industrially of importance. A porous membrane of a few micrometers having an excessive amount of particles contained therein is required in the porous structure of medicinal scaffold, a catalyst/electrode/filtering membrane for fuel cells, a biodegradable polymer porous membrane, a porous membrane for filters, a porous membrane used for fabrication of condensers, a porous filter of secondary batteries, or the like. Dispersion of the excessive amount of particles in a polymer cannot be easily carried out because the particles are entangled with one another due to the electrostatic attractive force of the particles, the hydrogen bond thereof, the Van der Waals'force, or the like. Therefore, Dispersion of the particles is performed by means of a physical agitation for a long time, an ultrasonic dispersion, and an addition of appropriate dispersing agent.

However, even though the particles are dispersed in the liquid state through the above means, they are cohered again when the solvent of the solution is dried or the polymer is solidified from the melted state. Therefore, a membrane with an excessive amount of particles uniformly dispersed therein cannot be easily achieved.

In addition, the process for manufacturing a continuous membrane from a polymer mixture containing the solid particles can be exemplified by a dip coating, a spin coating, an inkjet

printing, a silkscreen printing, or the like. These processes can be selected depending on the applications since each process has advantages or disadvantages according to the area to be coated, the thickness of membrane, the property of polymer solution. However, in the case where a large amount of solid particles must be dispersed in a polymer, in particular in case of manufacturing a membrane having fine particles of a few nanometers to a few micrometers, the particles are more severely entangled so that they cannot be easily dispersed. Each process has difficulties, such as, in the case where mass production is desired, a thin membrane of a few nanometers to a few micrometers must be fabricated, or the thickness of a membrane must be finely controlled.

In particular, batteries have a wide range of applications as an energy source for a portable and high-performance design, and a light, thin, short and compact design of electrical equipment and devices, which are closely related with the 21- human century life. For these purposes, a high-performance battery (cell) is an essential prerequisite. Therefore, a secondary battery (cell) or a fuel cell including a common battery (cell) has been widely researched in order to develop a portable and high-performance design and also a light, thin, short and compact design.

Among them, the secondary battery (cell) is of significant

importance, in terms of the recycling of resources, and the prevention of environmental contamination. In addition, it has been of great importance as a battery (cell) for the portable communication equipment, and also a battery (cell) for the storage of electricity.

The electrochemical reaction in the secondary battery (cell) depends on the inherent property of the electrode active material, and, in particular, is significantly affected by the filtering membrane and the electrolyte during the course of ion- transportation. Therefore, the core of battery (cell) development lies in selection of optimum materials and enhancement of its performance. Most researches are focused on a filtering membrane for preventing contact of the cathode and the anode while enabling a free movement of ions. A membrane made of polyolefine series polymer and fluoric polymer has been used as a filtering membrane of secondary batteries. Polyamide, polysulfone, polyolefine polymer, and copolymer can be a material suitable for a light, thin, short and small design of secondary batteries since they have a high chemical stability and a good workability, as compared with the conventional case of using a liquid.

In case of a conventional lithium polymer secondary battery (cell) using as the battery (cell) electrolyte a hybrid polymer electrolyte, which is a fluoric polymer developed by A. S.

Gozdz et al. in Bell Communication Research (Bellcore), a polymer membrane containing plasticizer is manufacture, the plasticizer is extracted to thereby form pores in the surface and inside of the membrane, and then a liquid electrolyte is injected into the pores, thereby providing a polymer membrane having ion-conductivity. In the case of this method, since the process before the introduction of the liquid electrolyte is not very sensible to moisture or oxygen, advantageously the operational environment can be relatively easily established.

However, since a plasticizer is used for forming the pores, a series of complicated and time-consuming processes are required in order to extract and dry the plasticizer.

In addition, as one example of home research and development, a hybrid polymer electrolyte having the ion- conductivity to lithium ion has been manufactured by dissolving polysulfone polymer in N-methylpyrollidone, casting it and dipping in a non-solvent such as distilled water to thereby form a porous membrane, and introducing a liquid electrolyte. In case of this case, however, the polysulfone used for manufacturing the polymer membrane does not have an adequate capacity to absorb the liquid electrolyte, and thus the polymer electrolyte fail to exhibit an adequate conductivity and produces a poor contact with the electrodes, and increases the interface resistance.

In addition, the filtering membrane for the secondary battery (cell) or a common battery (cell) must have a good mechanical strength so as not to be destroyed by an external force from the outside of the battery (cell) and thus create a contact between the electrodes due to the external force. In order to generate a high power, an adequate amount of electrolyte must be absorbed inside the filtering membrane to provide a high ion-conductivity between the electrodes (a low interface resistance with the electrodes).

Therefore, in order to accomplish the above purposes, there is a need to improve the material properties of the filtering membrane, and control the size, the structure, and the content of the pores. However, a satisfactory manufacturing process has not been proposed yet.

Furthermore, a fuel cell is an electricity generation device, in which, when hydrogen molecule (H) and oxygen molecule (02) are electrochemically reacted with each other, electricity and heat is generated while producing water, which can be considered as a reverse reaction of water electrolysis.

Depending on the type of electrolyte to be used, the fuel cell is categorized into five types: a phosphoric acid fuel cell (PAFC), an alkaline fuel cell (AFC), a polymer electrolyte membrane fuel cell (PEMFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), and a direct methanol fuel cell

(DMFC).

The basic structure of the fuel cell includes each electrode layer such as a fuel electrode (cathode) for receiving fuel and an air electrode (anode), and an electrolyte layer for partitioning the electrodes and transferring a cation. The operational principle utilizes the mobile electrons generated when hydrogen and oxygen are reacted in the cathode and the anode. The hydrogen gas is introduced into the cathode of the fuel cell to react with a catalyst contained in the electrode and produce hydrogen ion (H+) and electron (e-). The produce hydrogen ion is moved towards the anode via the electrolyte, and the electron is moved towards the anode via an external circuit and electrochemically reacts with in-flowing oxygen gas to thereby generate electric current (direct current) while producing water. At this time, heat is generated as a by- product. This heat is used for steam-generation for the self- reformer of the fuel cell system (in case of a fuel cell type having a reformer installed therein), or used for heating or cooling, or discharged as an exhausted heat when it is not particularly to be used. The direct current generated by the fuel cell may be altered into an alternating current by an inverter, or directly used for an electric power for DC motors.

As hydrogen gas as the fuel of fuel cells, pure hydrogen may be used, or hydrogen produced by reforming methane or

ethanol through a reformer may be utilized. In case of oxygen gas, pure oxygen can increase the generating efficiency of the fuel cell, but the oxygen storage cost and the increased weight must be considered Therefore, in many cases, air is directly used although it does not have a good generating efficiency. A solid polymer fuel cell uses mainly a catalytic electrode containing platinum in order to enhance its reactivity.

Particularly, in the polymer electrolyte membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC), the electrolyte is a solid polymer electrolyte membrane made of solid polymer and functions to transfer hydrogen ion (H+) form one electrode to the other. For this purpose, the polymer electrolyte membrane fuel cell (PEMFC) employs as the solid electrolyte membrane a cation exchange membrane in which a functional group assuming a negative electric charge is bonded to a hydrophobic polymer, thereby passing hydrogen ion (H+). A typical example therefor may be Nafion supplied by Dupont in the United States.

In this way, the cation exchange membrane used in the polymer electrolyte membrane fuel cell contains a functional group having a negative electric charge (typically, sulfonate group [so3~]) in the fine-pored wall of the membrane, and thus attracts only the oppositely-charged ion (cation) into the fine pores of the membrane. The oppositely charged ion (cation)

received inside the fine pores is weakly bonded with one negatively charged functional group of the cation exchange membrane. Thereafter, the cation is detached from the functional group and bonded again to next another functional group. This course of actions is repeated continuously such that the cation passes through the membrane. At this time, the identically charged ion (anion) or the solvent (water, etc.) fails to pass through the membrane.

In order to improve the reactivity in these reactions, it is necessary that the membrane be constituted of a porous membrane. The electrolyte membrane is preferred to be as thin as possible, in order to minimize the resistance (ion-transfer resistance) between two electrodes. Also, the membrane is preferred to be thin and simultaneously have an adequate mechanical strength, in order to prevent a mechanical failure (tearing or the like) when assembling the cell. However, a membrane meeting the above requirements has not been proposed yet.

In addition, in case of the direct methanol fuel cell, commonly platinum catalyst is dispersed in the electrolyte membrane to form a catalyst layer to increase its reactivity.

In the case of currently commercialized fuel cells, the activity of the platinum catalyst is not adequately reflected on the reaction, so that a large amount of platinum catalyst must be

used. If the amount of platinum catalyst is not enough, methanol is not decomposed and moved to the opposite electrode.

That is, the methanol crossover phenomenon cannot be prevented to deteriorate its performance significantly. This acts as a big obstacle to the commercialization of fuel cells.

In the commercialized direct methanol fuel cell, platinum catalyst is used in such a way that platinum is supported on carbon or like and dispersed in the electrolyte membrane.

However, this platinum-supported catalyst is not efficiently dispersed and cohered with each other, and also the surface of the catalyst is thickly coated with the polymer used as a binder, thereby significantly deteriorating its performance. That is, during the manufacturing process of fuel cells, the catalyst is mixed in the electrolyte solution such as Nafion or the like, and then pressed to form a catalyst layer or an electrode layer.

During this process, the catalyst is aggregated with each other and the surface of the catalyst is covered with the electrolyte polymer, so that the efficiency of catalyst is disadvantageously degraded.

Disclosure of Invention Technical Problem The present invention has been made in order to solve the above problems in the art occurring in the prior art, and it is

an object of the invention to provide a porous and continuous composite membrane, in which solid particles capable of improving the physical properties of the membrane and enhancing the functionality of the membrane are uniformly dispersed, in particular to provide a porous and continuous composite membrane with solid particles dispersed uniformly therein and having a thickness on the order of nanometers.

Another object of the invention is to provide a porous and continuous composite membrane having a good physical property, while having a thickness on the order of nanometers and a high content of pores.

A further object of the invention is to provide a porous and continuous composite membrane, in which solid particles capable of improving the properties of the membrane and enhancing the functionality thereof can be uniformly dispersed.

A further object of the invention is to provide a method of manufacturing a porous and continuous composite membrane with solid particles uniformly dispersed therein, which can enable mass production, easily control the thickness of the membrane, and manufacture the membrane in the form of thin film.

A further object of the invention is to provide a method of manufacturing a porous and continuous composite membrane having a thickness on the order of nanometers, a high content of pores, and a good physical property, which is suitable for mass

production and can easily control the thickness of the membrane.

A further object of the invention is to provide a battery (cell) including a filtering membrane, an electrolyte membrane, an electrode layer, or a catalyst layer, which has a mechanical strength to be able to prevent contact between the electrodes due to an external force and a high ion-conductivity, and in which a functional particle or a catalyst can be efficiently dispersed.

A further object of the invention is to provide a secondary battery (cell) including a filtering membrane, which can obtain the above functions while having a thickness on the order of nanometers, thereby enabling a light, thin, short and small design.

A further object of the invention is to provide a fuel cell including an electrolyte membrane, an electrode layer, or a catalyst layer, which has a high reactivity and a low resistance between the electrodes, and can be easily handled and has a high efficiency when the fuel cell is fabricated.

Technical Solution In order to accomplish the above object, according to one aspect of the invention, there is provided a porous and continuous composite membrane comprising a) a plurality of polymer nano-fibers, each of which is a mono-filament, a

continuous fiber, or a mixture thereof, the contacting points between the nano-fibers being fusion-bonded, and b) a plurality of solid particles evenly dispersed inside the plurality of polymer nano-fibers.

In addition, according to one embodiment of the invention, the porous and continuous composite membrane is dissolved in a soluble solvent such that the solid particles are dissolved from the porous and continuous membrane, thereby forming pores therein.

According another aspect of the invention, there is provided a method of manufacturing a porous and continuous composite membrane. The method of the invention comprises steps of: a) dispersing a solid particle in a polymer solution; b) electro-spinning the polymer solution with the solid particle dispersed therein to thereby produce a nano-fiber web ; and c) heating or heating/pressurizing the nano-fiber web, thereby producing a porous membrane.

In addition, the method of the invention may further comprises a step of d) forming a pore by dissolving the porous and continuous membrane in a soluble solvent in such a manner that the solid particle is dissolved from the porous and continuous membrane.

According to another aspect of the invention, there is provided a battery (cell) including a porous and continuous

membrane used as a filtering membrane, an electrolyte membrane, an electrode layer, or a catalyst layer. Here, the porous and continuous membrane comprises: a) a plurality of polymer nano- fibers, each of which is a mono-filament, a continuous fiber, or a mixture thereof, the contacting points between the nano-fibers being fusion-bonded, and b) a plurality of solid particles evenly dispersed inside the plurality of polymer nano-fibers.

In addition, according to another aspect of the invention, there is provided a secondary battery (cell) including the above porous and continuous membrane as a filtering membrane.

Furthermore, according to another aspect of the invention, there is provided a fuel cell including the above porous and continuous membrane as an electrolyte membrane, an electrode layer, or a catalyst layer.

Advantageous Effects According to the present invention, in the case where a large amount of functional particles are contained uniformly in a polymer desired by a user, a porous and continuous membrane having a functionality or an improved physical property can be obtained. Since the solid particles are easily dispersed, a porous and continuous membrane with fine particles dispersed uniformly therein can be achieved, in which the solid particle has a size of a few nano-meters to a few micrometers. Also, due

to the dispersion of fine particles, the resultant thin film with the solid particle dispersed therein can be made to be very thin. In addition, the content, the size and the shape of the pores in the porous and continuous membrane can be controlled, variously according to the user's desire.

In addition, the porous and continuous composite membrane of the invention has a wide range of applications, such as electric-electronic components such as a condenser, coating materials, medicinal scaffolds, an organic EL, a PDP, a biodegradable porous polymer membrane, a porous membrane for filters, a display, a fuel cell, a secondary battery (cell), and the like.

Furthermore, according to the manufacturing method of the invention, a large amount of solid particles can be efficiently dispersed. Since the dispersion is easily carried out, fine solid particles can be dispersed. Therefore, the solid particle to be dispersed can become smaller, thereby enabling the manufacturing of a thin film. The content, the shape, and the size of the pores in the porous and continuous membrane can be controlled.

Furthermore, the method of manufacturing a porous and continuous membrane of the invention can easily control the thickness of the membrane, and is suitable for mass production, along with the reduced manufacturing cost and fixing cost.

In particular, due to the improved mechanical strength through the dispersion of solid particles, the battery (cell) containing the porous and continuous membrane as the filtering membrane can avoid failure of the battery (cell) by an external force or a short-circuit between the electrodes, in the case where the battery (cell) is fabricated in a light and thin design.

By controlling the structure, the size and the content of the pores, the amount of electrolyte to be absorbed in the membrane is maximized, so that a high ion-conductivity and a low interface resistance can be achieved, thereby enabling fabrication of a high-efficient battery (cell). A continuous membrane having a fine porous structure and an ion-conductivity for a specific ion can be obtained, thereby enabling to fabricate a battery (cell) having an electrolyte membrane of high reaction efficiency. Through dispersion of catalytic particles or functional particles and efficient control of the dispersion, a battery (cell) having a high-performance catalyst layer and electrode layer can be fabricated.

In addition, in the case where the pore is formed by dissolving the soluble salt, various shapes and contents of the pore can be achieved through a simple process, relatively to the conventional manufacturing method of membrane. Therefore, the manufacturing process can be simplified, along with the easy control of the process.

In particular, in case of the secondary battery (cell) of the invention, the thickness control can be easily carried out, through a general mass production method. The thin films can be fabricated, depending on the application specifications. In this way, therefore, the entire weight of the battery (cell) can be reduced.

Furthermore, in case of the fuel cell of the invention, it includes a porous membrane so that an adequate reactivity can be achieved. The electrolyte membrane can be formed in the form of a thin film to reduce the resistance thereof, so that favorable energy efficiency can be achieved. The reduced strength due to the reduced thickness can be compensated through the dispersion of the solid particles.

Brief Description of Drawings Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which : FIG. 1 shows a schematic diagram of an electro-spinning system for use in the present invention; FIG. 2 is a SEM (scanning electron microscope) photograph shown the solid particles spun with polylactic acid (PLLA) according to a method of the invention; FIG. 3 is a SEM photograph showing a porous and continuous

membrane prepared in such a manner that a PLLA and solid particles are spun together into a nano-fiber web, which is pressed by a press ; FIG. 4 is a SEM photograph showing a porous and continuous membrane where the soluble salt particle is removed after pressing a PLLA fiber layer spun together with the soluble salt particles ; FIG. 5 is a SEM photograph showing the surface of a porous film for batteries which is composed of solid nano-particles and nano-fibers; and FIG. 6 is a SEM photograph showing the fractured surface of the porous film for batteries, which is composed of solid nano- particles and nano-fibers.

* REFERENCE NUMERALS IN DRAWINGS * 10 : Capillary tube 15 : Nano-fiber web 20 : Collector electrode Best Mode for Carrying Out the Invention The preferred embodiments of the present invention will be hereafter described in detail.

A porous and continuous composite membrane according to the invention comprises a plurality of polymer nano-fibers, each of which is a mono-filament, a continuous fiber, or a mixture

thereof and the contacting point between the fibers is fusion- bonded, and a plurality of solid particles evenly dispersed inside the plurality of polymer nano-fibers. The porous and continuous composite membrane of the invention is manufactured by dispersing solid particles into a polymer solution, and electro-spinning the solid particle-dispersed solution to thereby form mono-filaments and continuous fibers. The polymer nano-fiber web of nano-size, which is the mono-filaments, the continuous fibers, or their mixture, is heated or heated/pressurized to thereby produce the porous and continuos composite membrane of the invention.

In general, in order to form a porous and continuous membrane, the membrane must contain pores inside thereof, and the ingredients of the membrane are to be fine in order to disperse solid particles.

The nano-fiber used in the invention functions to form the pores and disperse the solid particles. That is, in case of polymer nano-fibers, in particular, of mono-filaments, generally they are arranged without orientation or regularity. When they are laminated, they are disorderly distributed, entangled and overlapped. In addition, the nano-fibers have a high specific surface area and are complicatedly overlapped with each other, and thus numerous contacting points exist between the fibers.

Therefore, the plurality of contacting points between the fibers

is fusion-bonded such that the aggregation of nano-fibers is transformed into a continuous membrane.

The solid particles used in the invention are dispersed in the fine nano-fibers. Therefore, the dispersion can be more effectively and uniformly achieved.

The diameter of the solid particle can be selected variously, depending on the applications of the porous and continuous membrane. In particular, when the solid particle has a spherical shape, it is preferred to have a diameter of 2nm to 30pm. When the solid particle is not spherical, its long axis is preferred to be 2nm to 30pom.

In addition, the material used as the solid particles, which is dispersed in the porous and continuous composite membrane, includes a soluble solid particle and a non-soluble solid particle. In particular, it is constituted of a material capable of electro-spinning such as an organic material containing a soluble salt, an inorganic material, a metallic material, an organic/inorganic solid particle coated with a metal, a carbon nano-tube, or the mixture thereof. The solid particle can be selected appropriately, depending on its application specification. That is, it can be applied in various forms, depending on its purposes such as improvement in the mechanical strength, or provision of the functionality.

In particular, in the case where the solid particle is a

soluble salt, the salt is dissolved, and the portion where the salt has existed is replaced with a pore, thereby enabling a porous membrane. In this case, advantageously the percentage, size, shape of the pore can be adjusted by controlling the content, the size, and the shape of the salt.

Specifically, the solid particle may be made of an organic material such as polymer, carbon, a carbon nano-tube, rubber, or protein; a functional ceramic inorganic material such as silica series, alumina series, titanium series, ITO (Indium Tin Oxide) series, dielectric ceramic, or piezoelectric ceramic; or a metallic material such as platinum, gold, silver, copper, ruthenium (Ru), aluminum, or copper. These materials can be used individually as a single material or in a mixture of at least two thereof. In addition, the surface of the solid particle, which has a size of a few or a few hundreds nanometer, can be coated with a metallic thin film or a functional material including a catalyst. Furthermore, since the solid particle is simply a mixture through dispersion, a common solid particle used in the art may be employed.

The solid particle is dispersed in a continuous membrane comprised of nano-fibers and its dispersion is relatively easy, as compared with a general continuous membrane. Therefore, a wide range of dispersion ratio can be achieved from a small amount to a larger amount of solid particles. In particular,

the solid particle is preferred to be contained in an amount of 2 to 95% by volume. When the solid particle is used in the above range, the workability such as in the electro-spinning can be more effectively improved.

In case of conventional solid particles, the finer the solid particle is, the severer they are entangled. Therefore, it is difficult employing a fine particle as the dispersion particle. In case of the solid particles used in the invention, the fine particles can be easily dispersed, and thus a finer particle can be utilized. Where the size of the solid particle is within the above range, its mass production and workability are excellent and thus its economical efficiency is distinguished.

The thickness of the porous and continuous membrane, which is constituted of the above constituents, may be controlled appropriately, depending on its applications and uses. In particular, the thickness is preferred to be within a range of 2nm to 500pm. This is, in case of the porous and continuous membrane constituted of nano-fiber according to the invention, a uniform dispersion of fine particles can be achieved. Therefore, in case of a membrane with solid particles dispersed therein, the finer the dispersed particle is, the thinner membrane can be fabricated. With the particles not damaged, a membrane having a thickness of the particle size or several times of the particle

size can be manufactured.

In addition, according to the invention, the above porous and continuous membrane is dissolved in a soluble solvent such <BR> <BR> that the solid particle, i. e. , the soluble salt is dissolved from the porous and continuous membrane and thus the place of the dissolved solid particle (soluble salt) is replaced with pores, thereby providing a porous and continuous membrane.

Advantageously, the percentage, the size and the shape of the pores can be controlled by controlling the content, the size, and the shape of the salt, etc.

In the porous and continuous membrane where the soluble salt is replaced with pores as described above, the percentage of the pores (porosity) can be adjusted appropriately by controlling the content of the salt, depending on the application and uses thereof. Preferably, the porosity is in an amount of 2 to 95% by volume based on the entire porous and continuous membrane. Within the above range of porosity, it has a good physical property and a good workability for mass production.

The porous and continuous composite membrane according to the invention has a wide range of applications, such as electric-electronic components, batteries, medicinal scaffolds, a porous membrane for filters, coating materials, a fuel cell, an organic EL, a PDP, a biodegradable porous and continuous

polymer membrane, and a display. Specifically, it includes a partition plate of electrolytic batteries, a catalyst/electrode/filtering membrane of fuel cells or a partition plate of secondary batteries (in particular, a filtering membrane for lithium ion secondary batteries), a scaffold for cell culture, a wet permeable membrane and waterproof clothes, a gas permeable membrane, a reverse osmosis filter, an ultra-filtration membrane, a fine-filtration membrane (water treatment, etc), or the like.

In particular, when a bio-medicinal scaffold employs the porous and continuous membrane of the invention, where the soluble salt used as solid particles is replaced for pores, it is favorable for the cell to be implanted in the surface of the fiber, and it is advantageous, as compared to the conventional polymer process or scaffold structure, since the blood and nerves is supplied to the cell through the empty space of the nano-fiber web. In addition, the nano-fiber web fabricated by electro-spinning has a narrow space. Therefore, as the cell begins to grow, the space for the cell to grow cannot be secured, in the case where only the electro-spinning is utilized. In the present invention, a solid salt particle, which has a size for the cell to grow in a polymer solution, is contained and dispersed above 90% by volume, and then the membrane is fabricated by the electro-spinning. Therefore, a space for the

cell to grow can be provided.

According to the invention, a method of preparing a porous and continuous composite membrane. In the method of the invention, solid particles are dispersed in a polymer solution, the solution with the solid particles dispersed therein is electro-spun to thereby create a nano-fiber web, and then the nano-fiber web is heated or heated/pressurized.

The polymer used in the invention is a compound as a raw material for the nano-fiber, and a material capable of being dissolved by a solvent.

The polymer may include all kinds of polymers, depending on the application of the porous and continuous membrane, as long as they are capable of electro-spinning. For example, in the case where the porous and continuous composite membrane is utilized for industrial purposes, it is preferable in terms of its economical efficiency that polyethylene, polypropylene, cellulose or the like is utilized. When it is applied to a human body, it is preferred to use a polymer such as polyglycol acid, polylactic acid, polylactic acid-glycolic acid copolymer, polycaprolactone, polyamino acid, polyanhydride, polyorthoester, or the like.

Although the above polymer is not particularly limited as long as it has a molecular weight to the extent to be electro- spun, it is in particular preferred to have a molecular weight

of above 10,000. If the polymer has a molecular weight of at least 10,000, a fiber form can be easily obtained when electro- spinning and the resultant porous and continuous composite membrane comes to have a good physical property. The higher the molecular weight of the polymer becomes, the thinner the diameter of the electro-spun nano-fiber becomes, and thus the more contacting points are created advantageously. Furthermore, in terms of the workability for mass production and the physical property of the resultant porous and continuous composite membrane, the polymer process can be carried out from the molecular weight of at least 2,000. In case of ultra high molecular weight polyethylene, a polymer having a molecular weight of up to 1,000, 000 to 5,000, 000 is processable.

The content of solvent in the polymer solution used in the invention is acceptable if it is appropriate to dissolve the polymer and disperse solid particles. Therefore, those skilled in the art can select according to the type of the polymer and the solid particle. In particular, the polymer solution is preferred to have a viscosity of 0.1 cp (10-3 Pa. s) to 103 Pa. s.

When the viscosity of the polymer solution is within the above range, the electro-spinning and the morphology of the nano-fiber web can be easily controlled.

The diameter of the solid particle can be selected variously, depending on the applications of the porous and

continuous membrane. In particular, when the solid particle has a spherical shape, it is preferred to have a diameter of 2nm to 30pLm. When the solid particle is not spherical, its long axis is preferred to be 2nm to 30pm.

In addition, the material used as the solid particles, which is dispersed in the porous and continuous composite membrane, includes a soluble solid particle and a non-soluble solid particle. In particular, it is constituted of a material capable of electro-spinning such as an organic material containing a soluble salt, an inorganic material, a metallic material, an organic/inorganic solid particle coated with a metal, a carbon nano-tube, or the mixture thereof. The solid particle can be selected appropriately, depending on its application specification. That is, it can be applied in various forms, depending on its purposes such as improvement in the mechanical strength, or provision of the functionality.

In particular, in the case where the solid particle is a soluble salt, the salt is dissolved, and the portion where the salt has existed is replaced with a pore, thereby enabling a porous membrane. In this case, advantageously the percentage, size, shape of the pore can be adjusted by controlling the content of the content, the size, and the shape of the salt.

Specifically, the solid particle may be made of an organic material such as polymer, carbon, a carbon nano-tube, rubber, or

protein; a functional ceramic inorganic material such as silica series, alumina series, titanium series, ITO (Indium Tin Oxide) series, dielectric ceramic, or piezoelectric ceramic ; or a metallic material such as platinum, gold, silver, copper, ruthenium (Ru), aluminum, or copper. These materials can be used individually as a single material or in a mixture of at least two thereof. In addition, the surface of the solid particle, which has a size of a few or a few hundreds nanometer, can be coated with a metallic thin film or a functional material including a catalyst. Furthermore, since the solid particle is simply a mixture through dispersion, a common solid particle used in the art may be employed.

The solid particle is dispersed in a continuous membrane comprised of nano-fibers and its dispersion is relatively easy, as compared with a general continuous membrane. Therefore, a wide range of dispersion ratio can be achieved from a small amount to a larger amount of solid particles. In particular, the solid particle is preferred to be contained in an amount of 2 to 95% by volume. When the solid particle is used in the above range, the workability such as in the electro-spinning can be more effectively improved.

Furthermore, according to the invention, in order to disperse solid particles in a polymer solution, all the agitating methods commonly used in mixing solid particles

homogeneously into a polymer solution may be employed. Also, an appropriate dispersing agent can be mixed. In particular, in case of dispersing solid particles of a nano-size, an ultrasonic dispersion method is preferable for uniform dispersion.

The polymer solution with the solid particles dispersed therein is electro-spun in order to create mono-filaments, continuous fibers, or a mixture thereof, which forms a nano-web having a nano-size. Of course, in case of the mono-filament, it can be fabricated so as to have a length having a nano-or micro-size.

FIG. 1 shows a schematic diagram of an electro-spinning system for use in the present invention. As illustrated in FIG.

1, a strong electric field is applied to a polymer solution or a melted material inside a capillary tube 10. Then, when the surface tension of liquid and the electrical force are in balance, a liquid drop formed at the tip of the capillary tube is transformed into a pointed conical shape and simultaneously the liquid is spun. The fiber spun as described above is accelerated and becomes thinner and thinner by the electrical field, and becomes unstable to be collected in a non-continuous form in the surface of the grounded metal, which is a collector electrode 20. That is, in the case where the material dissolved in the solution has a lower molecular weight, generally it exhibits the form of small particles, and thus called as an

electro-spraying. As in the present invention, when a material having a higher molecular weight is electro-spun, generally a fiber having a very small diameter of about 100nm is obtained in the form of a fiber, which does not have any directionality or regularity. Therefore, the process for manufacturing a fiber from a polymer having a high molecular weight is called an electro-spinning, dissimilar to the electro-spraying.

The present invention employs the electro-spinning process.

That is, an excessive amount of solid particles is dispersed in various conventional polymer solutions through a solid particle dispersion method, and then electro-spun to produce a nano-fiber web 15, which is an overlapped and entangled state of fine fibers of a few nanometers.

The nano-fiber web formed by electro-spinning the polymer solution is a nano-fiber with solid particles completely dispersed and loaded thereon. While the solvent is evaporated, this nano-fiber web is solidified in a short period of time.

Therefore, a state that the solid particles are uniformly dispersed in the nano-fiber is obtained.

The above-formed nano-fiber web is simply heated, or heated and simultaneously pressed to melt the polymer, in such a manner that a fusion-boding is formed at the contacting points between the fibers, thereby providing the porous and continuous composite membrane.

At this time, the heating may be applied to the whole web, or may be locally applied. A simple heating can be carried out, or a pressuring (pressing) is performed along with the heating.

That is, plural nano-fibers forms contacts between the fibers, which has various contacting angles, contacting positions, and contacting areas. When the temperature is increased above the melting temperature of the polymer by heating, or heating/pressing, the fiber becomes a melt state and the melt is accumulated in the contacted area. This accumulated melt generates a contact angle with the surface of the fiber, and the contact angle produces an attraction force, by which the fibers are drawn to each other. The nano-fibers are fusion-boned until the contact angle is vanished.

The nano-fiber, in particular, the mono-filament has a very small size and a light weight, and thus the surface tension is high, relatively to the gravity. Therefore, the fusion-bonding between the fibers can be efficiently effected. In particular, when the pressing is carried out simultaneously, the nano-fiber web can be transformed into a desired shape, and at the same time the porosity thereof can be controlled through the pressing.

Particularly, in the case where the heating and the pressing are carried out simultaneously, preferably, they are performed such that the resultant porous and continuous membrane has a thickness of 2nm to 500pm. As previously described, the

thickness of the porous and continuous membrane has a relationship with the size of dispersed particles and the extent of dispersion thereof. Therefore, when fine particles are dispersed, a thinner porous and continuous membrane can be formed.

The heating and pressing can be carried out through a roll pressing, a press pressing, an autoclave pressing, or the like.

According to the application of the above heating and pressing, a membrane of uniform thickness can be obtained, the thickness of the membrane can be easily controlled, and a mass production can be achieved.

Specifically, in the above roll pressing process, the melted nano-fiber web is passed and pressed through a nip roll, which is composed of at least 2 rolls and heated to above the dissociation-transition temperature of the polymer. After the press roll, while passing a cooling roll, it is adjusted below the dissociation-transition temperature of the polymer, thereby fixing the thickness of the film, together with cooling.

In the press pressing, the nano-fiber web is pre-heated using an oven, and then pressed in a press adjusted below the melting temperature of the polymer and cooled, thereby finally controlling the thickness of the film.

Finally, in the autoclave pressing, the spun nano-fiber web is hand-laid up inside the vacuum film such as nylon, polyimide,

polypropylene, or the like, and made vacuum. Then, a pressure of 2 to 100 atm is exerted to the nano-fiber web while heating the nano-fiber web to above the melting temperature of the polymer, to thereby reduce the number of pores present inside the nano-fiber web and form a flat surface thereof by means of the uniform pressure of the gas. Thereafter, after the film is completely formed, the nano-fiber web is cooled to below the melting point of the polymer while maintaining the pressure, thereby obtaining a final film.

In addition, according to the invention the manufacturing method of the porous and continuous composite membrane further comprises a step of dissolving the above-prepared porous and continuous composite membrane into a soluble solvent in such a manner that the solid particle is dissolved from the porous and continuous membrane to therefore form pores inside thereof.

The percentage, size, shape of the pores can be adjusted by controlling the content, the size, and the shape of the soluble salt.

In the porous and continuous membrane where the soluble salt is replaced with pores as described above, the percentage of the pores (porosity) can be adjusted appropriately by controlling the content of the salt, depending on the application and uses thereof. Preferably, the porosity is in an amount of 2 to 95% by volume based on the entire porous and

continuous membrane. Within the above range of porosity, advantageously, it has a good physical property and a good workability for mass production.

The manufacturing method of the porous and continuous composite membrane according to the invention employs an electro-spinning process and thus can coat a three-dimensional shape efficiently, even in the case where the whole product can be dipped into the coating solution, or the portion to be coated is formed of a complicated three-dimensional shape and thus cannot use a silk-screen printing, or the like. That is, only the portion to be coated can be heated and pressed, and then coated. In addition, advantageously a large amount of solid particles can be dispersed efficiently.

In addition, according to the present invention, a battery (cell) containing a porous and continuous membrane is provided. The battery (cell) of the invention comprises a porous and continuous membrane used as a filtering membrane, an electrolyte membrane, an electrode layer or a catalyst layer.

The porous and continuous membrane comprises a) a plurality of polymer nano-fibers, each of which is a mono-filament, a continuous fiber, or a mixture thereof and the contacting points between the fibers are fusion-bonded, and b) a plurality of solid particles evenly dispersed inside the plurality of polymer nano-fibers.

In general, a battery (cell) includes two electrodes and an electrolyte electrically connecting the two electrodes. For the purpose of a compact construction of battery (cell), the two electrodes are spatially very close to each other, and thus embraces a danger of a short-circuit due to contact between the electrodes. Therefore, in order to maintain the conductivity between the electrodes while avoiding the direct contact of the electrodes, a porous filtering membrane is included between the two electrodes so as to be capable of containing a large amount of electrolyte and thus minimize resistance. In addition, a certain type battery (cell) includes a porous electrolyte membrane capable of exchanging a specific ion, preventing short- circuit of the electrodes, and promoting the ion exchange. The fuel cell also includes an electrode layer having a porous structure where ionization of fuel and oxidation of the ionized fuel are performed, and which has conductivity for providing an electron passage and facilitates this reaction. Furthermore, the fuel cell includes a catalyst layer, which contains a catalytic material for promoting the ionization of hydrogen at the electrode layer and has a porous structure for obtaining reactivity.

In addition, according to the invention, a battery (cell) including as a filtering membrane, an electrolyte membrane, an electrode layer, or a catalyst layer thereof a porous and

continuous membrane. The porous and continuous membrane used in the battery (cell) of the invention is manufactured by a method according to the invention. According to the method of the invention, solid particles are dispersed in a polymer solution.

Then, the solution with the solid particles dispersed therein is electro-spun to thereby form a nano-fiber web, which is composed of a nano-fiber in the form of a mono-filament, a nano-fiber in the form of a continuous fiber, or a mixture thereof.

Thereafter, the nano-fiber web is heated, or heated/pressurized to obtain a porous and continuous membrane.

The polymer used in the present invention includes a compound, which can be used as a raw material of the fiber, and includes a polymer material capable of dissolving by a solvent, or electro-spinning in a melted form.

The polymer may include all kinds of polymers, depending on the battery (cell) using the porous and continuous membrane, as long as they are capable of electro-spinning. For example, a polymer stable against electrolyte can be used so that the porous and continuous membrane can act adequately as a filtering membrane. A polymer containing polyethylene, polypropylene, polyamide, polyimide, polysulfone, polyolefine, Nafion, polymergel, fluoric polymer, fluorene, polystyrene, a combination thereof, or the like may be used. In particular, with respect to the selection of polymer materials, a polymer

having conductivity to electrons or ions can be selected in order to form an electrode layer, a polymer material containing a functional group for transferring specific ions can be selected in order to form an electrolyte membrane, and a polymer material having a high mechanical strength and ion-conductivity can be selected in order to form a filtering membrane.

The range of molecular weight of the polymer, the solvent in the polymer solution, the viscosity, the size and shape of the solid particle, the mixing method, whether or not the additive is applied and the type of the additives may be applied in the same manner as described previously, in conjunction with the composite material. The material used as the solid particles dispersed in the porous and continuous membrane may utilize the same specifications as that of the solid particle used in the composite material. In particular, in order to provide a catalytic function, the particles used for a battery (cell) may include a catalyst particle where a catalytic material such as platinum, ruthenium, or the like is supported on carbon. In addition, it may include a nano-sized inorganic particle coated with a catalytic material such as platinum, ruthenium, or the like. The inorganic particle can be made of mica, or montmorillonite, which can be formed into a nano-sized particle. The function materials are coated preferably with a thickness of 0.2nm to 30pm, in order to provide an adequate

functionality and optimize the use of the functional material.

Furthermore, in order to increase the dielectric coefficient thereof, a dielectric particle may be contained, and in order to increase the conductivity thereof, a conductive particle may be included.

In addition, a method of supporting/coating a functional material such as platinum on the surface of the nano-sized organic or inorganic particle may employ an electroless plating, an elecro-plating, a sputtering process, a vapor deposition, a chemical vapor deposition (CVD), or a plasma coating process.

When required, a sintering process may be added to thereby improve the bonding force between the particle and the coating material. The coated nano-particles made of such as mica or montmorillonite has a plate-like shape having a very large surface area, and thus in the case where a functional material is coated, its effect can be maximized.

As described above, in the case where the solid particles with a catalytic material contained therein are dispersed, the resultant continuous membrane can be used as a catalytic layer of batteries. If a conductive particle is dispersed, an electrode layer of batteries can be formed. When the solid particles containing the catalytic material are dispersed in the continuous membrane containing a functional group capable of forming an electrolyte membrane, it can provide a catalyst and

electrode layer, which can serve as an electrode layer and a catalytic layer simultaneously.

Furthermore, particularly in the case where a carbon nano- tube is used as the solid particle, the porous and continuous membrane with the carbon nano-tube dispersed therein can be used in a battery (cell) including a secondary battery (cell) or a fuel cell, thereby taking advantage of the unique electrical and mechanical characteristics thereof. That is, according to the present invention, the carbon nano-tube is dispersed in a polymer solution, and thus the strand of the carbon nano-tube can be loosened without entangling.

As described above, the solid particle is dispersed in a continuous membrane comprised of fibers and its dispersion of solid particles is relatively easy, as compared with a general continuous membrane. Therefore, a wide range of dispersion ratio can be achieved from a small amount to a larger amount of solid particles. In particular, the content of solid particles dispersed in the polymer solution can be controlled appropriately so as to optimize the dispersion thereof, the easiness of electro-spinning, the functionality of the continuous membrane, or the like. Therefore, in the porous and continuous composite membrane, the content of the solid particles dispersed in the porous and continuous composite membrane can be adjusted variously, and its content can be

controlled within the range of 2 to 95% in terms of volume ratio.

The polymer solution with solid particles dispersed therein is electro-spun to form a nano-web, using the electro-spinning process illustrated in FIG. 1. According to the invention, an excessive amount of solid particles is dispersed in various conventional polymer solutions through a solid particle dispersion method, and then electro-spun to produce a nano-fiber web 15, which is an overlapped and entangled state of fine fibers having a size of a few to a few thousands nanometers. In the above elecro-spinning process, by controlling the conditions of electro-spinning, the web can be formed such that it is constituted of a nano-fiber in the form of a mono-filament, a nano-fiber in the form of a continuous fiber, or a mixture of the mono-filament and the continuous fiber. The nano-fiber web is spun in a state that the solid particles are completely dispersed and loaded in the fibers. As the solvent is evaporated from the web, this fiber web is solidified in a short period of time. Therefore, a state that the solid particles are uniformly dispersed in the fiber is achieved.

The fiber web prepared as described above is fabricated into a porous and continuous membrane, using the method described previously in connection with the composite material, which a simple heating is carried out, or heating and pressing (pressurizing) are performed simultaneously.

In addition, as described previously, in case of the porous and continuos membrane as prepared above, similarly, soluble salt is dispersed and the solid particle is dissolved in a soluble solvent such that the particles are dissolved therefrom to form pores, thereby providing a porous and continuous membrane for batteries.

In this way, the mechanical strength of the porous and continuous membrane can be adjusted by controlling the type, the size, and the dispersed content of the solid particles, and the size, the structure, and the content of the pores. Depending on the size, the structure, and the content of the pore, the content of electrolyte inside the membrane can be controlled.

Therefore, a membrane having a required ion-conductivity and a low interface resistance can be obtained.

Generally, in order to form a porous and continuous membrane, it must have a structure of having pores thereinside.

It is beneficial that the constituents of the membrane are fine in order for the solid particles to be dispersed. In addition, when intended to be used as an electrolyte layer, the prepared porous membrane can be heated and pressed at a higher temperature and with a higher pressure to thereby remove the pores. The continuous membrane as manufactured above has an excellent particle dispersion characteristic, as compared with the conventional membrane fabricated by coating.

The thickness of the porous and continuous membrane having the above-described constitution may be controlled appropriately, depending on the specifications of a battery (cell) to which the continuous membrane is applied. In particular, the thickness is preferred to be in the range of 2nm to 500pm. This is, in case of the porous and continuous membrane constituted of the fibers according to the invention, a uniform dispersion of fine particles can be achieved. Therefore, in case of a membrane with solid particles dispersed therein, the finer the dispersed particle is, the thinner membrane can be fabricated. In this way, the resistance of the continuous membrane can be minimized.

With the particles not damaged, a membrane having a thickness of the particle size or a few or a few hundreds times of the particle size can be manufactured. In addition, the manufactured membrane is overlapped in several layers and pressed, to thereby fabricate a thicker membrane. The electro- spinning can be repeated several times to the same place, and then the resultant product can be heated and pressurized to manufacture a thicker membrane.

In addition, when a carbon nano-tube is used as the solid particle to be dispersed, it can be necessary that the carbon nano-tube is oriented in a certain direction, when required. In this case, if the carbon nano-tube and the polymer are spun together through the electro-spinning, it is spun in such a way

that the carbon nano-tube is adsorbed around the nano-fiber or in the surface thereof. Therefore, the carbon nano-tube can be dispersed, and at the same time, oriented in a certain direction.

Also, if the electrode, to which the fiber web is received, is formed of a wheel and the electrode wheel is rotated with a high speed while electro-spinning the nano-fiber, the orientation of the carbon nano-tube can be promoted. In case of the above oriented film, the membrane is anisotropic electrically and mechanically, and thus can be applied to the field of a battery (cell), a second battery (cell), a fuel cell, an electron- emitting element, or the like.

In addition, according to the invention, the above porous and continuous membrane is dissolved in a soluble solvent such <BR> <BR> that the solid particle, i. e. , the soluble salt is dissolved from the porous and continuous membrane and thus the place of the dissolved solid particle (soluble salt) is replaced with pores, thereby providing a porous and continuous membrane.

Advantageously, the percentage (content), the size and the shape of the pores can be controlled by controlling the content, the size, and the shape of the soluble salt, etc. In this case, an insoluble salt and a soluble salt can be dispersed together and only the soluble salt can be dissolved to thereby be replaced with pores. Therefore, the porosity can be controlled by the dispersion of the soluble salt and the extent of fusion-bonding

in the fibers, and its mechanical strength can be controlled by the dispersion of the insoluble salt.

In the porous and continuous membrane where the soluble salt is replaced with pores as described above, the percentage of the pores (porosity) can be adjusted appropriately by controlling the content of the salt, depending on the specifications of a battery (cell) to which the membrane is applied. Preferably, the porosity is in an amount of 2 to 95% by volume based on the entire porous and continuous membrane.

Within the above range of porosity, it has a good physical <BR> <BR> property (mechanical property, ion-conductivity, etc. ) and a good workability for mass production. In this way, the structure, the content, and the size of the pore can be controlled so as to be able to absorb as much electrolyte as possible per unit volume.

The battery (cell) may include all of a general primary battery (cell), a secondary battery (cell), and a fuel cell. The primary and secondary batteries may include a zinc-manganese battery (cell), an alkaline battery (cell), a lithium-ion battery (cell), a lead battery (cell), a nickel-cadmium battery (cell), a lithium ion battery (cell), or the like.

Preferably, the present invention can be applied to the lithium- ion battery (cell). The fuel cell may include a phosphoric acid fuel cell (PAFC), a alkaline fuel cell (AFC), a polymer

electrolyte membrane fuel cell (PEMFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), and a direct methanol fuel cell (DMFC). Preferably, the present invention can be applied to the polymer electrolyte membrane fuel cell and the direct methanol fuel cell.

The secondary battery (cell) of the invention comprises a porous and continuous membrane as the filtering membrane thereof, and the porous and continuous membrane contains a) a plurality of polymer fibers in which the contacting points between the nano-fibers are fusion-bonded, and b) a plurality of solid particles dispersed uniformly in the plurality of polymer nano- fibers.

The secondary battery (cell) includes various types of secondary batteries. In particular, a lithium-ion battery (cell) is preferred. In this case, the polymer material may be exemplified by polyamide, polysulfone, polyolefine, copolymer, and fluoric polymer, which have a high mechanical strength and a high ion-conductivity.

Furthermore, the dispersion of the solid particles may function to improve its mechanical strength when a thin film is formed.

The porous and continuous membrane applied to the filtering membrane of the secondary battery (cell) may be manufactured by dispersing solid particles in a polymer solution, electro-

spinning the solution dispersed with the solid particles to form a fiber web, and heating, or heating/pressurizing the formed fiber web. Alternatively, solid particles made of a soluble salt are dispersed in a polymer solution, and the solution with the solid particles dispersed therein is electro-spun. Then, the spun product is dissolved in a solvent capable of dissolving the solid particle to thereby form a nano-fiber web, which is heated or heated/pressurized, thereby finally providing the porous and continuous membrane for batteries.

In the manufacturing of the porous and continuous membrane, in case of a secondary battery (cell), the resistance between the electrodes needs to be reduced in order to constitute a high efficient battery (cell), and thus the electrolyte membrane must have a thin thickness. For this purpose, a heating/pressing process including the roll pressing, the press pressing, or the autoclave pressing may be carried out, or a combination thereof may be applied. In case of the film manufactured according to the above method, since the porous and continuous membrane has a thin thickness, in order to reinforce the mechanical strength of the filtering membrane, the mechanical strength of the membrane can be improved, using the dispersion of the solid particles.

Furthermore, in case of the electrolyte membrane for the fuel cell of the invention, the size, the shape, the content, the type of the solid particles, and the content of the pore

(porosity) can be applied, in the same manner as previously described.

A secondary battery (cell) is often used in a portable form, and thus a simple, small, light and thin design is required.

The porous and continuous membrane of the invention can be applied efficiently since it can be formed in the form of a thin film while maintaining the mechanical strength thereof. In case of a lithium battery (cell), a synergetic effect can be achieved, <BR> <BR> i. e. , the reduction in its weight by using lithium, and also the reduction in its weight by fabricating it in the form of thin films.

In addition, the fuel cell of the invention comprises a porous and continuous membrane as the electrolyte membrane, the electrode layer, and the catalytic layer, and the porous and continuous membrane contains a) a plurality of polymer fibers in which the contacting points between the nano-fibers are fusion- bonded, and b) a plurality of solid particles dispersed uniformly in the plurality of polymer nano-fibers.

The fuel cell of the invention may include various types of fuel cells using a porous membrane as the electrolyte membrane.

In particular, a specific type of fuel cells relevant to the present invention is exemplified by a polymer electrolyte membrane fuel cell (PEMFC) and a direct methanol fuel cell (DMFC).

Particularly, in case of the solid polymer electrolyte membrane type, the mechanical contact between the electrodes is avoided to thereby prevent a short-circuit. It includes an electrolyte membrane, which contains a functional group for ion- transportation and is placed contacted between both electrodes in order to serve simultaneously as an ion-exchange membrane for selectively performing the ion-transfer between both electrodes, an electrode layer for facilitating the supply of fuel and collecting current, a porous catalytic layer for performing reaction with fuel and generating hydrogen, and a catalyst and electrode layer containing a catalytic material in the electrode layer and for performing the functions of both layers.

Therefore, the porous and continuous membrane, or the porous and continuous membrane, in which a soluble salt is transformed into pores, serves as an electrolyte membrane for exchanging hydrogen ion, in the case where it is constituted of a polymer containing a functional group capable of exchanging ions. Specifically, the material for the electrolyte membrane can use Nafion (supplied by Dupont in U. S.). In case of a fuel cell, a porous electrolyte membrane is required as the electrolyte membrane. For example, in case of a hydrogen fuel cell, the ionization of hydrogen from hydrogen gas and the ion- transportation are carried out at the electrolyte membrane. In order to fabricate a high efficient hydrogen fuel cell by

facilitating this reaction, it is more favorable to have the wider reactive interface where the hydrogen gas reacts with the functional group, and it is beneficial that the whole fuel cell has a compact size. For this purpose, the present invention provides a porous structure using a fusion-bonding of the contacting points between the fine nano-fibers, or a porous and continuous membrane in which a soluble salt is replaced with pores.

In addition, the porous and continuous membrane, or the porous and continuous membrane, in which a soluble salt is transformed into pores, can constitute an electrode layer for facilitating the supply of fuel and collecting current, in the case where electron or ion transfer is constituted of a polymer or the dispersion of conductive solid particle is performed.

When the porous and continuous member is used as an electrode layer, the electrode can be constituted of the porous and continuous body of the invention only, or in the form that the porous and continuous body is combined with a plate-like metallic electrode using a conductive wire.

In addition, the porous and continuous membrane, or the porous and continuous membrane, in which a soluble salt is transformed into pores, can constitute a porous catalytic layer for performing reaction with fuel and facilitating the generation of hydrogen ion, in the case where solid particle

containing a catalytic material is dispersed. In the case where the continuous membrane is constituted of a polymer capable of transferring electron or ion and solid particle containing a catalytic material is dispersed inside the continuous membrane, it can constitutes a catalytic electrode layer for performing reaction with fuel to promote the generation of hydrogen ions, facilitating the supply of fuel, and collecting current.

Furthermore, in case of a direct methanol fuel cell (DMFC), in order to obtain the same effect while minimizing methanol crossover and minimizing the amount of catalytic material used, solid particles having a size of a few nano-meters, which are made of Nafion or other appropriate polymers and coated with a catalytic material such as platinum or the like, are dispersed and spun on the surface of the electrolyte membrane, so that a porous membrane containing the catalytic material as solid particles is formed on the electrolyte membrane, thereby obtaining a catalytic electrode layer.

As previously described, the solid particles to be dispersed is prepared in such a manner that a functional metal including platinum is coated in the form of a thin film on the surface of inorganic or organic nano-particles made of such as mica or montmorillonite, using an electroless plating, an elecro-plating, a sputtering process, a vapor deposition, a chemical vapor deposition (CVD), a plasma coating process, or

the like. These nano-particles is contained in nano-fibers and attached to the electrolyte membrane, and then fixed to the electrolyte membrane using the pressing process or the like, thereby enabling to control the methanol crossover.

Alternatively, a web is prepared separately by containing these coated particles in the nano-fibers, and then an electrolyte membrane with no pore can be fabricated through a pressing process. The fabricated electrolyte membrane can be served as an electrolyte membrane of fuel cells.

In particular, the coated nano-particles made of such as mica or montmorillonite has a wide plate-like shape having a very large surface area, and thus in the case where it is contained in the electrolyte membrane of fuel cells, methanol to permeate the electrolyte membrane is made to be reacted, so that the methanol crossover can be maximally prevented.

The electrolyte membrane as prepared above can control the methanol transfer since the methanol is reacted by platinum contained the porous membrane and run out, while generating methanol crossover when methanol passes through the electrolyte membrane. In addition, the opposite electrode, where hydrogen ion is reacted to generate water, is formed with a membrane containing a catalyst using the same method as in the present invention, thereby efficiently carrying out the water generation.

Furthermore, the dispersion of the solid particles may

function to improve its mechanical strength when a thin film is formed.

The porous and continuous membrane applied to the electrolyte membrane, an electrode layer, a catalyst layer, or a catalytic electrode layer of the fuel cell may be manufactured by dispersing solid particles in a polymer solution, electro- spinning the solution dispersed with the solid particles to form a fiber web, and heating, or heating/pressurizing the formed fiber web. Alternatively, solid particles made of a soluble salt are dispersed in a polymer solution, and the solution with the solid particles dispersed therein is electro-spun. Then, the spun product is dissolved in a solvent capable of dissolving the solid particle to thereby form a nano-fiber web, which is heated or heated/pressurized, thereby finally providing the porous and continuous membrane for fuel cells.

In the manufacturing of the porous and continuous membrane, in case of a fuel cell, the resistance between the electrodes needs to be reduced in order to constitute a high efficient battery (cell), and thus the electrolyte membrane must have a thin thickness. For this purpose, a heating/pressing process including the roll pressing, the press pressing, or the autoclave pressing may be carried out, or a combination thereof may be applied. In case of the film manufactured according to the above method, since the porous and continuous membrane has a

thin thickness, a careful handling is required when fabricating a fuel cell. For reinforcement thereof, the mechanical strength of the membrane can be improved, using the dispersion of the solid particles.

Furthermore, in case of the electrolyte membrane for the fuel cell of the invention, the size, the shape, the content, the type of the solid particles, and the content of the pore (porosity) can be applied, in the same manner as previously described.

The following examples are provided to more fulLy illustrate the present invention, which is not limited thereto.

Example 1. A composite film prepared by dispersing montmorillonite particle in the cellulose polymer 8% by weight of cellulose diacetates was dissolved in a mixed solution of methylene chloride: ethanol = 9: 1.8 to 60% by volume of solid particle made of montmorillonite (MMT) and having a diameter of 3 to 10pm was uniformly dispersed in the above solution. Then, the solution with the solid particles dispersed therein was electro-spun. Here, when electro-spinning, a voltage of 10 to 20kV was applied, and the distance between the electrodes was 15 to 20cm. an aluminum film was employed in the collector electrode. In addition, the diameter of the spinning nozzle was 0.1 to 0.3mm, and the electro-spinning was carried out at room temperature with atmospheric pressure. In

this case, it has been found out that, as the content of MMT is increased, the resiliency of the nano-fibers is increased and thus the pores are formed in the form of very firm structure.

Example 2. A composite film prepared by dispersing salt particles in the polylactic acid (PLLA) cellulose polymer Polylactic acid (Mn = 218, 000, Mw/Mn = 1.55) was dissolved in chloroform. Then, 3 to 10% by volume of montmorillonite particles were mixed with the above solution, followed by electro-spinning. In addition, 90% by volume of a mixture consisting of aluminum bicarbonate particles, sodium chloride particles, and montmorillonite particles is mixed to form pores inside of a scaffold. Here, when electro-spinning, a voltage of 15kV was applied to produce the solution speed of 1 ml/hr, and the distance between the electrodes was 15 to 20cm. An aluminum film was in the collector electrode. In addition, the diameter of the spinning nozzle was 0.1 to 0.5mm, and the electro- spinning was carried out at room temperature with atmospheric pressure.

FIG. 2 shows the solid particles spun with polylactic acid (PLLA) and uniformly dispersed without coagulation.

FIG. 3 shows a fiber bundle manufactured by pressing a nano-fiber web, which was prepared by the electro-spinning. In this case, it has been found that the fiber bundle maintains the shape of fiber due to a lower pressing temperature, and the

structure of a porous film is maintained since the space between the fiber bundles is maintained.

FIG. 4 shows a porous and continuous membrane prepared by spinning together with soluble salt particles and then removing the soluble salt particle. It shows that the place where the salt particle is removed is replaced for pores, and it has a very uniform distribution of pores.

Example 3. A porous polystyrene (PS) film for batteries 30% by weight of polystyrene was dissolved in a solvent of dimethylformamide (DMF), and then 0 to 10% by volume of montmorillonite particles were mixed with the above solution, followed by electro-spinning. Here, when electro-spinning, a voltage of lOkV was applied to produce the solution speed of 0.8 ml/hr, and the distance between the electrodes was 15 to 20cm. A aluminum film was employed in the collector electrode. In addition, the diameter of the spinning nozzle was 0.1 to 0. 5mm, and the electro-spinning was carried out at room temperature with atmospheric pressure. The spun nano-fiber was pressed using a roll pressing machine. The structure of the porous membrane prepared by the above procedures is shown in FIGS. 5 and 6. It has been found that the above prepared membrane has nano-sized pores between the nano-fibers and a very rigid membrane can be formed. The size of pores and the rigidity of the membrane could be adjusted by controlling the pressure of

the roll pressing machine or the press.

Example 4. A porous film for batteries obtained by dispersing salt particles Except that 0 to 90% by volume of solid particles prepared by mixing aluminum bicarbonate particles, sodium chloride particles and montmorillonite (MMT) particles in a certain predetermined ratio were mixed, instead of the montmorillonite particles, the electro-spinning was carried out in the same manner as in the previous example 1. The above-prepared porous film was dissolved in a solvent capable of dissolving the soluble salt in the solid particles, and thus a final porous film was manufactured. In this case, it has been found out that, as the content of MMT is increased, the resiliency of the nano- fibers is increased and thus the pores are formed in the form of very firm structure.

Industrial Applicability According to the present invention, in the case where a large amount of functional particles are contained uniformly in a polymer desired by a user, a porous and continuous membrane having a functionality or an improved physical property can be obtained. Since the solid particles are easily dispersed, a porous and continuous membrane with fine particles dispersed uniformly therein can be achieved, in which the solid particle

has a size of a few nano-meters to a few micrometers. Also, due to the dispersion of fine particles, the resultant thin film with the solid particle dispersed therein can be made to be very thin. In addition, the content, the size and the shape of the pores in the porous and continuous membrane can be controlled, variously according to the user's desire.

In addition, the inventive porous and continuous composite membrane has a wide range of applications, such as electric- electronic components such as a condenser, coating materials, medicinal scaffolds, an organic EL, a PDP, a biodegradable porous polymer membrane, a porous membrane for filters, a display, a fuel cell, a secondary battery (cell), and the like.

Furthermore, according to the manufacturing method of the invention, a large amount of solid particles can be efficiently dispersed. Since the dispersion is easily carried out, fine solid particles can be dispersed. Therefore, the solid particle to be dispersed can become smaller, thereby enabling the manufacturing of a thin film. The content, the shape, and the size of the pores in the porous and continuous membrane can be controlled.

Furthermore, the inventive method of manufacturing a porous and continuous membrane can easily control the thickness of the membrane, and is suitable for mass production, along with the reduced manufacturing cost and fixing cost.

In particular, due to the improved mechanical strength through the dispersion of solid particles, the battery (cell) containing the porous and continuous membrane as the filtering membrane can avoid failure of the battery (cell) by an external force or a short-circuit between the electrodes, in the case where the battery (cell) is fabricated on a design basis of lightness and thinness. By controlling the structure, the size and the content of the pores, the amount of electrolyte to be absorbed in the membrane is maximized, so that a high ion- conductivity and a low interface resistance can be achieved, thereby enabling fabrication of a high-efficient battery (cell).

A continuous membrane having a fine porous structure and an ion- conductivity for a specific ion can be obtained, thereby enabling fabrication of a battery (cell) having an electrolyte membrane of high reaction efficiency. Through dispersion of catalytic particles or functional particles and efficient control of the dispersion, a battery (cell) having a high- performance catalyst layer and electrode layer can be fabricated.

In addition, in the case where the pore is formed by dissolving the soluble salt, various shapes and contents of the pore can be achieved through a simple process, relatively to the conventional manufacturing method of membrane. Therefore, the manufacturing process can be simplified, along with the easy control of the process.

In particular, in case of the secondary battery (cell) of the invention, the thickness control can be easily carried out, through a general mass production method. The thin films can be fabricated, depending on the application specifications. In this way, therefore, the entire weight of the battery (cell) can be reduced.

Furthermore, in case of the fuel cell of the invention, it includes a porous membrane so that an adequate reactivity can be achieved. The electrolyte membrane can be formed in the form of a thin film to reduce the resistance thereof, so that favorable energy efficiency can be achieved. The reduced strength due to the reduced thickness can be compensated through the dispersion of the solid particles.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.