Technical Field

[0001] The present invention relates to the field of reusable batteries and particularly batteries which are activated by addition of a liquid such as water.

Background of the Invention

[0002] The problem with many conventional batteries is that they tend to deteriorate in effectiveness over time during storage. This is particularly undesirable when an emergency situation arises where effectively functioning batteries may be required to power a torch, a radio or other piece of equipment.

[0003] Water-activated batteries have been employed as one way of addressing the above problem as they can be stored for a relatively long period of time in an inactive state - that is, when water or a water-based substance has not yet been added - and then be activated when required by adding water or a water-based substance for use without substantial loss in effectiveness.

[0004] However, existing water-activated batteries also exhibit certain drawbacks. For instance, in order to add water to an electrolyte powder mixture within the battery to activate the battery, a pipette is typically required to inject water under pressure into the battery casing via a small aperture in an end of the battery. This can be a tedious and messy procedure particularly for young children and if the pipette is inadvertently lost, the battery cannot be properly activated. Moreover, it is difficult to effectively deliver the water into contact with the bulk of the electrolyte powder within the battery due to existing internal battery configurations. Consequently, this results in inefficient use of the water-activated battery.

[0005] A further problem associated with current water-activated batteries is that the casing tends to be made from magnesium which expands and deforms over time during use. When the battery has deformed, it is not only difficult to remove from an electronic device, but it may also damage the electronic device in doing so. Summary of the Invention

[0006] The present invention seeks to alleviate at least one of the problems discussed above in relation to the prior art.

[0007] The present invention may involve several broad forms. Embodiments of the present invention may include one or any combination of the different broad forms herein described.

[0008] In a first broad form, the present invention provides a battery including:

a metal tube having opposed first and second ends, and an inner peripheral surface defining a chamber in which a liquid-activatable powder mixture is disposed therein;

a permeable separator sheet for electrically isolating the powder mixture from the metal tube;

a conductive rod having a first end located adjacent the first end of the metal tube and extending to a second end in contact with the powder mixture; and

a passage extending between the first and second opposed ends of the metal tube to allow flow of liquid therethrough, wherein said liquid is able to be delivered from the passage into contact with the powder mixture via the permeable separator sheet substantially along the length of the metal tube so as to activate the powder mixture, whereby the activated powder mixture is adapted to generate a potential difference between the conductive rod and the metal tube.

[0009] Preferably, the metal tube may include at least one of zinc, magnesium, aluminium, and a combination thereof.

[0010] Preferably, the first end of the metal tube may be substantially sealed by a first end cap and the second end of the metal tube may be releasably sealable by a second end cap. Preferably, the liquid may be adapted for delivery into the chamber via the second end of the metal tube when unsealed. Typically the first end cap may include a plastic material and the second end cap may include a metal material such as stainless steel.

[001 1] Preferably, the second end cap and the second end of the metal tube may include substantially similar diameters. Preferably, the second end cap may be adapted for screw-threaded engagement either directly with the second end of the metal tube, or, adapted for screw- threaded engagement with an outer casing surrounding the metal tube so as to allow the second end cap to releasably seal the second end of the metal tube. Also preferably, the second end cap includes a metal material adapted for electrical communication with the metal tube when releasably sealing the second end of the metal tube. Typically, the second end cap may also be in direct physical contact with the metal tube when releasably sealing the second end of the metal tube which may serve as a negative electrode of the battery in use.

[0012] Advantageously, a liquid may be delivered into the chamber of the metal tube relatively easily and quickly in order to activate the powder mixture by pouring or otherwise scooping the liquid into the metal tube via the unsealed second end of the metal tube. This may also alleviate the additional costs and packaging space associated with certain prior art batteries which require use of a pipette to squirt liquid into the battery via a tiny aperture in the battery casing. In this regard, the present invention may also be advantageous in that it is possible to visually determine if an appropriate amount of water has been delivered into the metal tube. In contrast, it is difficult to determine if an appropriate amount of water has been squirted into a battery by a pipette until excess water has leaked out of the aperture in the battery casing.

[0013] The use of a metallic second end cap adapted to releasably seal the second end of the metal tube is also advantageous in that the second end cap may be readily separated from the metal tube for ease of recycling and/or re-usage if required. That is, the need for relatively expensive recycling processes such as metal shredding, furnacing and magnetic separation which is generally required to separate an integrally formed conventional battery may be alleviated due to the fact that the metallic second end cap may be readily separated from the metal tube of the battery.

[0014] Preferably, the first end of the conductive rod may extend outwardly of the first end of the metal tube via an aperture disposed in the first end cap. Preferably, second end of the conductive rod may be substantially embedded within the powder mixture. Typically, the conductive rod may include at least one of a brass, a carbon and a stainless steel material.

[0015] Preferably, the passage extends an entire length of the metal tube. The passage may extend in a substantially straight path between first and second opposed ends of the metal tube. Typically, the passage may extend in a substantially parallel path relative to an elongate axis of the metal tube. Alternatively, the passage may include a curved path. Advantageously, a curved path may allow greater exposure to surface area of the permeable separator sheet and/or powder mixture along the length of the metal tube.

[0016] Advantageously, the passage allows a liquid to be delivered into contact more uniformly and evenly throughout the powder mixture in the metal tube as water flows through the length of the metal tube. Accordingly, this may assist in increasing power output and efficiency of the battery. In contrast, when a liquid is squirted into certain prior art batteries, the water is required to penetrate, with relative difficulty, through the powder mixture from the top of the powder mixture. Moreover, certain prior art water-activated batteries include a sponge within the metal tube which upon absorbing water, does not thereafter tend to easily release the absorbed water into contact with the powder mixture. The efficiency and power output of such prior art batteries are therefore adversely affected in comparison to the present invention.

[0017] Preferably, the passage may includes a groove formed in the inner peripheral surface of the metal tube. Typically, at least six grooves may be formed in the inner peripheral surface. Typically, the six grooves may be evenly spaced apart around the inner peripheral surface. The groove may be cut or etched out of the inner peripheral surface of the metal tube using suitable machinery and known techniques.

[0018] Preferably, the liquid includes water or any water-based liquid.

[0019] Preferably, the present invention may include an outer casing surrounding the metal tube which is adapted to substantially reinforce the metal tube against deformation through heat and the like. In prior art batteries which do not use such an outer casing, the battery may be more susceptible to deformation under heat stress which then makes it difficult to effect removal of the battery from a device once deformed.

[0020] More preferably, the outer casing may include a plastic material. Preferably, when the second end cap releasably seals the second end of the metal tube, the second end cap may be releasably engaged with the plastic outer casing by way of screw-threaded engagement whereby the second end cap is in electrical communication with the metal tube. Preferably, the second end cap may also be in direct physical contact with the second end of the metal tube when it is screwed on to the plastic outer casing. Advantageously, a plastic outer casing may reduce the weight of the battery compared to use of other materials such as metal. This may therefore alleviate transportation costs when shipping large volumes of the battery. The use of a plastic casing may further alleviate potentially short circuiting of the battery where loose powder mixture within the metal tube comes into contact with the outer casing. Furthermore, a plastic outer casing may be relatively easily and cheaply debossed with commercial indicia and/or be decorated (e.g. using colours) during manufacture for marketing and/or aesthetic purposes. Also advantageously, the inclusion of a plastic outer casing may further assist in providing up to around 85% reusability and recyclability of embodiments of the present invention. For instance, a plastic outer casing, a metal second end cap, and a brass first end of the conductive rod may be conveniently re-used whilst a plastic first end cap and the metal tube may be simply dismantled for recycling. In particular, it is noted that a plastic outer casing may be easier to re-use or recycle as there is no bonding or fusing involved with the metal tube which enables relatively easy dismantling of embodiments of the present invention.

[0021] Alternatively, the outer casing may include a metal such as stainless steel. Typically, the outer casing includes a thickness of between approximately 0.2 to 1 mm and preferably, a thickness of 0.5mm.

[0022] Preferably, the powder mixture may include a metal oxide powder. Typically, the metal oxide may include at least one of an activated carbon, manganese dioxide, iron oxide and crystalline silver oxide.

[0023] Preferably, the permeable separator sheet may extend substantially along the length of the inner peripheral surface and lie flush against the inner peripheral surface. Typically, the permeable separator sheet may include at least one of a permeable paper material, a permeable synthetic polymer material, and a permeable natural polymer material. Typically, the permeable separator sheet may be preformed or folded to complement the contour of the inner peripheral surface of the metal tube. Preferably, a portion of the permeable separator sheet may be folded over the powder mixture adjacent the second end of the metal tube to alleviate leakage of loose powder mixture outwardly of the second end of the metal tube.

[0024] Preferably, a retaining member may be disposed in the chamber adjacent the second end of the metal tube which abuts against the folded over portion of the permeable separator sheet. Preferably, the retaining member includes at least one aperture to allow fluid communication therethrough from the second end of the metal tube into contact with the folded over portion of the permeable separator sheet. Typically, four apertures may be disposed in the retaining member.

[0025] Advantageously, the retaining member may provide a safety mechanism in that if the second end cap is released from the second end of the metal tube, for instance by a child, the retaining member assist in holding the permeable separator sheet firmly folded over the powder mixture adjacent the second end. The powder mixture may not then be potentially ingested by a child, or, otherwise leaked out of the metal tube. Moreover, the aperture in the retaining member enables liquid to flow therethrough into contact with the powder mixture from the top of the powder mixture.

[0026] In a second broad form, the present invention provides a battery including: a metal tube having opposed first and second ends, the first end being substantially sealed by a first end cap and the second end being releasably sealable by a second end cap, and an inner peripheral surface defining a chamber in which a liquid-activatable powder mixture is disposed therein;

a permeable separator sheet disposed between the powder mixture and the inner peripheral surface for electrically isolating the powder mixture from the metal tube;

a conductive rod having a first end positioned outwardly of the first end of the metal tube via an aperture disposed in the first end cap, said first end extending to a second end which is embedded in the powder mixture; and

a groove formed in the inner peripheral surface of the metal tube extending between the first and second opposed ends to allow flow of liquid therethrough, wherein said liquid is able to be delivered from the groove into contact with the powder mixture via the permeable separator sheet substantially along the length of the metal tube so as to activate the powder mixture, whereby the activated powder mixture is adapted to generate a potential difference between the conductive rod and the metal tube.

[0027] In a third broad form, the present invention provides a method of activating a battery, the battery including:

a metal tube having opposed first and second ends, and an inner peripheral surface defining a chamber in which a liquid-activatable powder mixture is disposed therein; a permeable separator sheet for electrically isolating the powder mixture from the metal tube;

a conductive rod having a first end located adjacent the first end of the metal tube and a second end embedded in the powder mixture; and

wherein, the method includes the steps of:

(i) delivering a liquid into the chamber; and

(ii) channelling the liquid along the passage, wherein said liquid is able to be delivered from the passage into contact with the powder mixture via the permeable separator sheet substantially along the length of the metal tube so as to activate the powder mixture, whereby the activated powder mixture is adapted to generate a potential difference between the conductive rod and the metal tube.

[0028] Advantageously, a liquid-activated battery may provide a longer shelf-time given that it is not activated until water is added to activate it. In contrast, existing prior art batteries tend to deteriorate immediately upon manufacture and may not be usable after a certain number of years in storage. A liquid-activated batter however may remain usable for a relatively long period of time until activated.

Brief Description of the Drawings

[0029] The present invention will become more fully understood from the following detailed description of a preferred but non-limiting embodiment thereof, described in connection with the accompanying drawings, wherein:

Figure 1 shows an exploded side-view of a first embodiment of the present invention;

Figures 2(a) and (2b) show a side cross-sectional view and an end-view of a metal tube of the first embodiment respectively;

Figures 3(a) and (3b) show perspective views of opposing ends of a plastic outer casing which surrounds the metal tube in the first embodiment;

Figure 4 shows a second end cap for releasably sealing a second end of the metal tube of the first embodiment; Figures 5(a) and 5(b) show a side cross-sectional view and an end-view of a metal outer casing of an alternative embodiment of the present invention respectively;

Figure 6 shows a perspective view of a permeable separator sheet moulded to fit flush against an inner peripheral surface of the metal tube for use in electrically isolating a powder mixture in the metal tube from the metal tube in the first embodiment of the present invention;

Figure 7 shows a perspective view of a retaining member for holding a portion of the permeable separator sheet folded over the powder mixture adjacent a second end of the metal tube;

Figure 8 shows a perspective view of a brass cap of a conductive rod in the first embodiment which functions as a positive electrode of the battery; and

Figure 9 shows a perspective view of a first end cap for sealing a first end of the metal tube of the first embodiment.

Detailed Description of Preferred Embodiments

[0030] Preferred embodiments of the present invention will now be described with reference to the drawings.

[0031] Turning firstly to Fig. 1 a first embodiment battery (1) is shown in exploded side-view. The battery (1) remains inactivate until a liquid such as water or any other suitable water-based liquid is added to it and may therefore remain in storage and usable for a considerably longer time than conventional batteries which tend to deteriorate immediately upon manufacture. When water is delivered into contact with a powder mixture disposed inside the battery, the powder mixture becomes activated and generates a potential difference between electrically-isolated positive and negative electrodes of the battery which may then be used as an electrical power source. The features and operation of this embodiment will be described in detail as follows. [0032] The battery (1) includes a cylindrical-shaped metal tube (2) having opposed first and second ends as shown in Figs. 1 and 2. The first end (2a) of the metal tube is sealed by a plastic first end cap (3) and the second end (2b) is releasably sealable by a second end cap (4) via screw-threaded engagement. The first and second end caps (3,4) are shaped to substantially complement the shape and dimensions of the first and second ends (2a, 2b) of the metal tube (2). The first and second end caps (3,4) are shown in Figs. 9 and 4 respectively in the drawings.

[0033] The second end cap (4) is formed from a metallic material such as stainless steel such that when the second end cap (4) is screwed in sealing position adjacent the second end (2b) of the metal tube (2), the metal tube (2) and the second end cap (4) are in electrical communication. In this embodiment, when the second end cap (4) is releasably sealing the second end (2b) of the metal tube (2), the second end cap (4) is actually attached by screw-threaded engagement with a plastic outer casing (6) which surrounds the metal tube (2). The plastic outer casing (6) will be described in greater detail below. An o-ring (10) is disposed around the second end cap (4) and is configured to fit in relation to the second-end cap (4) whereby it sits within the outer casing. When the second end cap (4) is screwed on to the plastic outer casing (6) it is also in direct physical contact with the second end (2b) of the metal tube (2) so as to enable electrical communication between the second end cap (4) and the metal tube (2) which together form a negative electrode of the battery in use.

[0034] Referring now to Figs. 2(a) and 2(b), the metal tube (2) is shown having an inner peripheral surface (2c) which defines a chamber (2d) for storing the powder mixture. Six evenly spaced grooves (2e) are formed along the inner peripheral surface (2c) of the metal tube (2) which extend in substantially straight paths between the first and second ends (2a, 2b) of the metal tube (2). The grooves (2e) are cut or etched out of the inner peripheral surface so as to attain suitable sizes and dimensions to allow water to freely flow therethrough from the second end (2b) toward the first end (2a) of the metal tube (2).

[0035] The powder mixture in this embodiment is a metal oxide powder such as manganese dioxide, iron oxide or crystalline silver oxide which substantially fills the chamber (2d) of the metal tube (2). The powder mixture is physically and electrically isolated from the inner peripheral surface (2c) of the metal tube (2) by a permeable separator sheet (9). An outer surface of the permeable separator sheet (9) lies flush against the inner peripheral surface (2c) of the metal tube (2) whilst a reverse side contacts with the powder mixture.

[0036] The permeable separator sheet (9) is made from a permeable paper although a synthetic or natural polymer material could be used in alternative embodiments.

[0037] Conveniently, the permeable separator sheet (9) enables wicking of the liquid therethrough and into contact with the powder mixture in use without unduly retaining the liquid as is the case with sponge-like materials. As shown in Fig. 9, an end portion (9a) of the permeable separator sheet (9) is folded over against the powder mixture adjacent the second end (2b) of the metal tube (2) to assist in keeping the powder mixture from leaking out of the second end (2b) of the metal tube (2) when unsealed.

[0038] The battery (1) also includes a conductive rod (5) having a first end (5a) consisting of a brass cap and a second end (5b) consisting of a carbon stick. The carbon stick (5b) extends inwardly of the metal tube (2) from the first end (2a) substantially towards the second end (2b) of the metal tube (2) and is embedded within the powder mixture. The brass cap (5a) coupled to the carbon stick (5b) extends outwardly of the first end (2a) of the metal tube (2) via an aperture (3a) in the first end cap (3). The brass cap (5a) includes a flanged rim (5b) as shown in Fig. 8 which is adapted to lie flush against a rim of the first end (2a) of the metal tube (2). The conductive rod (5) is electrically isolated from the metal tube (2) and the metal second end cap (4).

[0039] The diameter of the aperture (3a) in the first end cap (3) is designed to be snug-fitting with the diameter of the carbon stick (5b) so as to alleviate escape of any loose powder mixture through the first end (2a) of the metal tube (2). An o-ring is disposed between the first end cap (3) and the first end (2a) of the metal tube (2) for sealing purposes.

[0040] When the battery (1) is in operation, the conductive rod (5) acts as a positive electrode of the battery (1) to which positive ions produced as a result of the chemical reaction at the metal tube (2) will flow to via the permeable separator sheet (9) and powder mixture. [0041] In order to activate the battery (1), the second end cap (4) is unscrewed to allow water to be poured into the chamber (2d) via the unsealed second end (2b), or, by submerging the battery (1) into water to scoop up water into the chamber (2d). Water which enters the chamber (2d) is able to flow freely into contact with the powder mixture substantially along the length of the metal tube (2) due to the paths provided by the six grooves (2e) formed in the inner peripheral surface (2c).

[0042] Water flows from the grooves (2e) substantially along an entire length of the battery (1) and through the permeable separator sheet (9) due to its wicking effect and then into contact with the powder mixture. As would be appreciated, the surface area of powder mixture which the water is able to contact with and penetrate into is considerably greater than in the case of certain prior art batteries which allow water contact and/or penetration to be made only at the top of the powder mixture. In alternative embodiments, it may possible to provide grooves which may include curved paths so as to increase the amount of surface area of the powder mixture along the length of the metal tube via which water may be delivered into contact with it from the grooves via the permeable separator sheet.

[0043] Once the second end cap (4) has been screwed back onto the plastic outer casing to releasably seal the second end (2b) of the metal tube (2), the battery (1) is ready for use in powering load devices. In certain embodiments it is conceivable that water may be injected into the chamber (2d) under pressure by use of a pipette inserted into a relatively smaller opening in a sealed second end (2b) of the metal tube (2). However, this option is less desirable given the need for an additional pipette and the lack of visibility in determining when the battery (1) has been injected with an appropriate amount of water.

[0044] Once water has contacted with the powder mixture, the powder mixture chemically reacts with the metal tube (2) whereby a potential difference is generated between the positive electrode consisting of the conductive rod (5), and, the negative electrode consisting of the second end cap (4) and the metal tube (2) to which it is electrically in contact with. Whilst the permeable separator sheet (9) disposed between the positive electrode (i.e. the conductive rod) and the negative electrode (i.e. the metal tube and second end cap) of the battery (1) physically and electrically isolates the positive and negative electrodes of the battery, it also allows for free flow of positive ions created as a result of the chemical reactions from the negative electrode metal tube (e) towards the positive electrode in use so as to continue to generate and maintain the potential difference. Electrons formed at the negative electrode are therefore able to flow from the negative electrode through a load device and back to the positive electrode of the battery (1).

[0045] The metal tube (2) is formed from zinc although in alternative embodiments it may be formed from magnesium, aluminium or any combination thereof. The use of zinc material in the metal tube (2) will result in a relatively less energetic chemical reaction within the battery (1) which extends the operational lifespan of the battery as the zinc material in the metal tube (2) takes longer to corrode in use. Conversely, the use of magnesium to form the metal tube (2) gives rise to a relatively vigorous chemical reaction within the battery (1) which shortens the operation lifespan of the battery (1) due to faster depletion of the magnesium metal tube (2). It would also be appreciated that the use of a zinc metal tube (2) results in a relatively lower output power level from the battery (1) over its longer operational lifespan whilst a relatively higher output power is provided by the use of a magnesium metallic tube over its relatively shorter operational lifespan. In certain tests, the initial current spoke of a battery (1) using magnesium as the metal tube (2) has been measured at approximately 3.6 A.

[0046] Typically, if the metal tube (2) is formed from magnesium it is expected that the battery lifespan may last for approximately 2-3 weeks whilst the use of zinc as the metal tube (2) may last for 2-3 months. It is conceivable that in yet alternative embodiments of the present invention, a sacrificial anode may be included in the battery which serves to slow down the corrosion of the metal tube material.

[0047] When the potential difference across the battery (1) falls to an unusable level, water can be re-filled in to the battery (1) as described above to reactivate the powder mixture and to again generate a usable potential difference across the positive and negative electrodes of the battery (1).

[0048] As mentioned above, a plastic outer casing surrounds the metal tube (2) for reinforcing the metal tube (2) against deformation due to heat and other stresses during use.

[0049] In this embodiment the plastic outer casing (6) is made from a plastic material (6) which is preformed and/or moulded and adapted to slide over the metal tube (2) as a snug-fitting outer sleeve. As shown in Fig. 3(a), the outer casing (6) includes an aperture (6b) at one end which fits neatly over the first end (5a) of the conductive rod (5). An outer surface (6a) of the plastic outer casing (6) may be relatively easily debossed and/or decorated with branding and/or other commercial indicia. The use of a plastic casing (6) is also advantageous due to the relative lightness of the plastic material.

[0050] In alternative embodiments, the outer casing could be made from a metal (7) such as stainless steel as shown in Figs. 5(a) and 5(b). Where the outer casing (7) is a metal material, it will be in electrical communication with the metal tube as an inner peripheral surface of the outer casing surrounds and snugly abuts against the outer peripheral surface of the metal tube (2).

[0051] The plastic outer casing (6) and metal outer casing (7) would both include internal screw-threads (6a, 7a) as shown in Figs. 3(b) and 5(a) for releasable engagement with a complementary screw-thread portion (4a) disposed on the second end cap (4) as shown in Fig. 4. If a plastic outer casing (6) is used, it would be necessary for the second end cap (4) to be firmly screwed inwardly of the plastic outer casing (6) and into contact with the second end (2b) of the metal tube (2) to ensure that they are electrically connected and the second end cap (4) can function as the negative electrode in use. Where a metal outer casing (7) is used, the second end cap (4) need not be screwed in as deeply as it will be already in electrical communication with the metal tube (2) via the metal outer casing (7).

[0052] In alternative embodiments where no outer casing is used, the second end cap (3) could be releasable engaged by screw-thread engagement or any other suitable attachment means directly to the second end (2b) of the metal tube (2).

[0053] Turning to Fig. 7, a plastic retaining member (8) is shown which abuts against and holds the end portion of the permeable separator sheet (9) folded over adjacent the second end (2b) of the metal tube (2). The retaining member (8) includes a cylindrical cross-section of similar diameter to that of the second end (2b) of the metal tube (2) such that it fits snugly inside the second end (2b) of the metal tube (2). The retaining member (8) also includes four segment-shaped apertures (8a) passing entirely through from one side to the other. Advantageously, the retaining member (8) not only assists in holding the folded over permeable separator sheet (9) in place to keep powder mixture from escaping, but it also allows water to flow through it into contact with the powder mixture via the permeable separator sheet (9) material. When water is delivered into the unsealed second end (2b) of the metal tube (2), not only will water flow along the length of the metal tube (2) via the grooves (2e) in the inner peripheral surface (2c), but some water may also flow through the apertures (8a) in the retaining member (8) and into contact with the powder mixture via the top of the powder mixture covered by the folded over permeable separator sheet (9).

[0054] It would be appreciated that during operation of the battery (1) corrosion of the metal tube (2) tends to result in waste products building up at the metal tube (2) which may at least partially occlude liquid-flow via the grooves (2e) over time. In this regard, the ability of the retaining member (8) to allow water to pass through it and into contact with the top of the powder mixture is advantageous.

[0055] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described without departing from the scope of the invention. All such variations and modification which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope of the invention as broadly hereinbefore described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps and features, referred or indicated in the specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

[0056] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge.