"PROCESS FOR THE EXTRACTION OF CHEMICAL COMPOUNDS FOUND IN SECONDARY LITHIUM BATTERIES"

The present invention refers to a chemical process that allows the recovery of lithium compounds found in secondary lithium-ion batteries, i.e., a process involving few simplified stages under relatively low temperatures, in addition to using a low-toxicity solvent that is easy to be obtained and handled.

As it is common knowledge among the specialists in the area, the lithium-ion batteries (also known as Li-ion) are the most recent products to gain the cellular phone market as they present a lot of advantages when compared to other types of batteries, such as: a) High voltage - Lithium batteries present a nominal voltage of about 4 V, depending on the cathodic material used, compared to 1.5 V for most primary and secondary battery systems. A greater cell voltage reduces the number of elements in a given battery to its half. b) High power density - The energy stored at a lithium battery (over 200 Wh/kg and 400 Wh/L) is 2 to 4 times greater than the one stored at a zinc anode battery. c) Operation within a large temperature range - Lithium batteries can be used at temperatures ranging from -40 to 70 ⁰ C. d) High power density - Most lithium batteries are designed to operate in high currents and voltages. e) Long storage time (self-discharge) - Lithium batteries can be stored for long periods of time even at high temperatures.

Therefore, the batteries are more compact and lightweight, with increased cycling capacity, which make them more efficient. By taking such advantages into account, compared to the nickel-cadmium and nickel-metal- hydride batteries, the use of lithium batteries has gradually grown and, as a result, the disposal increases each year.

In spite of being very expensive, the lithium batteries advantages allow them to be used as serial devices in most cellular phone models.

Environmental organizations estimate that users replace their cell phones every 18 months and, up to 2005, almost 130 million cell phones had been disposed of (the equivalent to almost 65.000 tons). This has resulted in much concern about the depletion of mineral resources, in addition to the environmental impact caused by inadequate disposal of cell phone batteries.

When batteries are stored, they may leak and release toxic and corrosive material. When such disposal is made in urban areas, the battery components may contaminate soil, water and crops, which later on will be consumed by humans.

In addition to environmental benefits, the lithium-ion batteries reuse assumes great importance, as their components hold a significant economic value.

The lithium batteries do not contain toxic metals, however, they are likely to bum if the metallic lithium is exposed to humidity while the cells are in the process of corrosion. In order to be appropriately discarded, the batteries should be completely discharged so that all the metallic lithium is cleared. Almost all lithium systems contain inflammable and toxic electrolyte.

Sorting batteries adds to the cost of recycling. Average users do not know which chemical components are present in the batteries. For most users, a battery is just a battery. The logistics of collecting, transporting and sorting batteries turns recycling into an expensive procedure. Conventional recycling processes start by the removal of combustible substances such as plastic and insulating material using gas from a thermal oxidizer. The thermal oxidizer gases are sent to the plant purifier where they are neutralized in order to get the pollutants removed. This process results in

clean and "naked" batteries, which contain valuable metallic content. The batteries are then cut in small parts, which are then warmed up until the metal turns into liquid. Non-metallic substances are removed with heat. Different alloys are combined according to their weight. The literature describes a few lithium-ion battery recycling methods. The United Kingdom opened its first lithium battery recycling plant in December 2003, which is based upon an electrolytic reduction process. This plant is devoted to cobalt-lithium oxide and nickel-cobalt oxide battery recycling. This technology allows the separation of cobalt from lithium by selectively dissolving lithium through LiCoO ₂ reduction. This process also allows lithium fluorides as well as organic solvents, which are a part of the electrolyte, to be recovered with a high purity level and reused in the manufacturing of new lithium batteries. During the process, batteries are first grinded in a knife mill and, next, treated with an organic solvent to dissolve the electrolyte and separate it from the other components. The sediments obtained from the first separation are treated with a second organic solvent. The solid components resulting from this second dissolution are: Materials from negative electrodes (anode-copper) and positive electrodes (cathode-aluminum) and materials that are part of the separator. Such materials can be separated either by their density or magnetic properties. The filtrate obtained from this separation is transferred to an electrolytic cell. As the electrolysis takes place, the cobalt-lithium oxide is reduced to cobalt oxide. The lithium leaves the electrode and migrates to the solution. The lithium hydroxide solution is decanted and the cobalt oxide is washed and removed to be stocked.

Another patent describes a Li-Co battery recycling process. At first, the cathode material is dissolved in acid. Next, base is added so that the transition metal precipitation may occur (cobalt, for instance). The resulting product is filtered, thus recovering cobalt hydroxide (precipitated). The filtrate is evaporated, dried and treated with alcohol. The selective lithium solubilization

process occurs at this stage. After that, the sofution passes through an fon- exchange column, thus obtaining high purity LiCI lithium chloride.

Another method shows that lithium batteries are cryogenicalfy cooled and grinded. Next, the pH of the mixture is adjusted by adding lithium hydroxide. A number of lithium salts are precipitated at this stage, depending on the type of cathode used in the battery. Afterwards, the precipitate is separated through filtration and dissolved in sulfuric acid. The resulting solution is efuted through an ion-exchange column, recovering the lithium as lithium carbonate.

In spite of their efficiency, the conventional methods for recovering chemical compounds found in secondary lithium batteries require a high amount of energy. Different from other methods, this takes six to ten times the amount of energy in order to recover metals from recycled batteries.

Another disadvantage regarding conventional methods for recovering chemical compounds from secondary lithium batteries is the fact that when the battery is grinded and the lithium is dissolved, the traditional chemical precipitation methods are used, which are less selective in some cases.

Therefore, one of the objectives of this invention is to provide a process to extract chemical compounds found in secondary lithium that involves a few stages, economically feasible, efficient and at low energy consumption. . Another objective regarding this invention is to provide a process to extract chemical compounds found in secondary lithium batteries with reactions that occur at low temperatures.

The present invention also intends to provide a process for the extraction of chemical compounds found in secondary lithium batteries that is able to employ easy-to-use, low-toxicity level solvents.

These and other objectives and advantages of the present invention can be achieved through a process for the extraction of chemical compounds found in secondary lithium batteries based on the dissolution of

lithium compounds in hydrated alcohol solution and acetone, filtering and drying the obtained compounds. After the cutting, electrodes are placed in a solution of hydrated alcohol and acetone (5%). They remain immersed for a predetermined period of time in laboratory solution, preferably for two hours. During the immersion, lithium salt extraction is explicit. Afterwards, the electrodes are removed and the solution is filtered, thus separating the lithium carbonate and the lithium hydroxide from the organic solution, which resulted from the initial reaction.

The invention will be described in the only figure attached to this document, which represents the flowchart regarding the extraction of lithium compounds found in secondary lithium batteries.

According to the figure, the process for the extraction of lithium compounds found in the secondary lithium batteries comprises six macro-stages: i) initial opening and separation (1); ϊi) extraction of lithium compounds through an organic solution (2); iff) positive electrode dissolution (3); iv} aluminum separation (4); v) cobalt compounds precipitation (5); and vi) copper collector separation (negative electrode) (6).

The process of opening the batteries (1) is performed by using a cutting device developed in the project. Such device cuts the polymeric carcass and the metal can. In addition to the polymeric carcass and the metal carcass, the terminals and the side nickel tape are separated at this stage. The polymeric carcass, the metal can, nickel tapes, aluminum and separated terminals are sent to companies specialized in recycling such components. At the same time, both electrodes and separators undergo a process for the extraction of lithium components.

Lithium, originated from salt used to prepare the electrolyte, as well as the active material from electrodes, is recovered as lithium hydroxide and lithium carbonate.

In the extraction stage of the lithium compounds (2), the compounds are extracted from the separators and the electrodes by immersing

' them into a mixture of commercial ethanol and acetone at 5% preferably with a proportion of 700m 1710 batteries. After approximately two hours, the extraction is completed, the electrodes and separators are removed and the solution is filtered in order to obtain the lithium compound, which is dried and weighed, obtaining a mass of 5g/10 batteries. The filtrate holds the alcohol/acetone solution and residues of solvent and battery electrolyte. At this stage, besides obtaining the lithium compounds, the separators, nickel contacts, aluminum contacts and plastic tapes are separated manually and the positive and negative electrodes are used in the forthcoming stages.

The hydrated ethanol prevents the lithium to react violently. As this reaction occurs in a soft way, there is no need for cooling during the reaction as there is no explosion risk. Thus, the process becomes more simple and economically feasible.

The presence of acetone in the solution causes the dissolution of the compounds to be more efficient, the amount of acetone suggested in the mixture is within a range between 15 and 5%. However, it is suggested to use only 5% of acetone for maximum efficiency. The equations next show how the dissolution of lithium compounds and the subsequent formation of oxide and lithium carbonite occur.

The formation of lithium hydroxide and lithium carbonate, originated from salt used to prepare the electrolyte, as well as the active material from electrodes, occurs from the following reactions: 1) solubilization of lithium compounds in ethanol, forming lithium ethoxide and hydrogen-ion and reactions of lithium ethoxide with water C ₂ H ₅ OH + Li ⁺ → C ₂ H ₅ OLi + H+ C ₂ H ₅ OLi + H ₂ O → C ₂ H ₅ OH + LiOH

2) Reaction of lithium-ion with water: Li ⁺ + H ₂ O → LiOH + H ⁺

3) Reaction of lithium carbide from positive electrode with water: LiC ₆ + H ₂ O → HC ₆ + LiOH

4) Reaction of lithium carbonate formation: 2LiOH + H ₂ CO ₃ → Li ₂ CO ₃ + 2H ₂ O

The filtrate obtained from filtering (alcohol, acetone and batteries electrolyte residues) is distilled, obtaining alcohol at 96°GL that can be used again in the extraction process of lithium compounds.

After lithium compounds are extracted, the positive electrodes are immersed in acid aqueous solution for the dissolution of aluminum and cobalt and lithium oxide (3). The obtained results showed that a solution of hydrochloric acid at 20%, a volume of 700 mL/10 batteries and mechanical stirring were appropriate for a complete dissolution reaction.

The following reactions show how the positive electrode dissolution occurs:

Al + 3HCI → AICf ₃ + 3/2H ₂

LiCoO ₂ + 4HCI → CoCI ₃ + LiCI + 2H ₂ O After the dissolution of the positive electrode (3) a wine- colored solution is obtained, which is typical of cobalt, graffiti and agglutinant compounds sedimented at the bottom of the container. This solution is filtered and then the graffiti and the aggfutinant remain in the filter whereas the aluminum and the cobalt remain in the filtrate. Both the graffiti and the agglutinant are dried. After the dissolution, the precipitation of aluminum compounds

(4) present in the firtrate begins. Ammonium hydroxide (NH ₄ OH) 30% is used for that purpose. At first, ammonium hydroxide is added until the point at which the pH becomes acid and, next, the temperature is increased up to 7O ⁰ C for

approximately two hours so that the aluminum precipitation occurs, according to the following reaction:

3NH ₄ OH + AICI ₃ → AI(OH) _3, + 3NH ₄ CI

This solution is filtered. The precipitate is dried and afterwards weighed.

For the cobalt compound precipitation (5), the filtrate must have a basic pH. To make the solution basic, it is recommended to add a saturated lithium hydroxide solution, and once lithium itself is already a common ion no other ion will contaminate the solution. The precipitation reaction of cobalt compounds is presented next:

Co ²⁺ + 2OH- → Co(OH) ₂

After the precipitation, the precipitate filtration and drying processes take place. To proceed with the separation of the negative electrodes (6), they are placed into a container with holes. Such container is placed inside a becker and, next, a hydrochloric acid solution at 5% is added to the electrodes so that both graffiti and agglutinant are removed- After ten minutes of mechanical stirring, the graffiti and the agglutinant are released, passing through the holes. The copper remains in the perforated container. The acid solution is filtered, the graffiti and the agglutinant remain in the filter-paper, and the acid solution remains in the filtrate. It can be reused in the process fora couple of times.

The currently presented invention involves both mechanical and chemical stages. The combination of these stages makes up a simple, efficient and low energy-consumption process. This is its main advantage compared to state-of-the-art recycling processes.

Besides the economical aspects regarding the recovery and reuse of materials described previously, this invention also contributes to the conservation and preservation of the environment.

Although a preferable solution has been described and illustrated, it is important to stress that other solutions can be performed within the same scope.