Abstract:
A metal-gas cell storage battery, such as a zinc-air cell battery, has one or more battery cells wherein each battery cell comprises a metallic anode sandwiched between a pair of gas cathodes. Each gas cathode is disposed within a rigid retaining structure. The retaining structures of each gas cathode are attached to one another by an expandable soft pocket capable of holding an electrolyte. The anode is disposed within the soft pocket. The cell is mechanically refueled by expanding the soft pocket to allow easy removal from the cell of the spent anode and easy insertion into the cell of a fresh anode.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of Ser. No. 09/682,012, filed Jul. 9, 2001, “Metal-Gas Cell Battery with Soft Pocket,” now abandoned, which is a continuation-in-part of Ser. No. 09/681,260, filed Mar. 9, 2001, now abandoned, “Metal-Gas Cell Battery with Soft Pocket.” 
    
    
     BACKGROUND OF INVENTION 
     This invention relates generally to metal-gas cell batteries, such as metal-air cell batteries, and, more particularly, to mechanically rechargeable metal-air cell batteries. 
     More powerful, longer-lasting batteries are a high priority item for all countries seeking to replace hydrocarbon fueled vehicles with smogless electrically powered vehicles. In this regard, a great deal of research is presently focused on metal-gas cell batteries, such as zinc-air batteries. Zinc-air batteries have among the highest theoretical specific energy content of all known battery types. Many problems, however, must be overcome before vehicles powered by zinc-air batteries are regarded as acceptable alternatives to hydrocarbon burning vehicles. 
     All metal-gas cell batteries comprise a plurality of cells wherein each cell has at least one gas-diffusion cathode and a metallic anode separated by a quantity of alkaline electrolyte and some form of mechanical separation sheet. In the operation of metal-gas cell batteries, a reactant gas, such as oxygen, reacts at each gas-diffusion cathode to form anions. At each anode, the anions react with metallic anode material. The process creates an electrical potential between each cathode and each anode. When the cells are connected in series, the combined electrical potential of all of the cells can be considerable, and can be used as a source of electrical power. As can be seen, however, the operation of the battery gradually depletes the available metallic anode material and the battery has to be periodically recharged. 
     Metal-gas cell batteries can be recharged either electrically or mechanically. Electrical recharging can be easily adapted to existing power networks, but electrically rechargeable batteries have a markedly limited service life. Moreover, an electrically rechargeable metal-gas battery requires a bi-functional or additional gas diffusion electrode. Having to use such a bi-functional or additional gas diffusion electrode requires that the battery be unduly heavy, bulky and complicated. 
     Accordingly, the recharging mode of choice for metal-gas cell batteries is presently mechanical refueling, whereby the spent metallic anode is physically replaced with a fresh anode. Mechanical refueling can be accomplished in two ways. In a first way, the metallic anode comprises metallic pellets or powder suspended within the electrolyte. When the metallic pellets or powder becomes spent, the metallic pellets or powder is pumped from the cell and fresh pellets or powder is pumped into the cell. U.S. Pat. Nos. 3,981,747, 5,006,424, 5,434,020 and 5,558,947 disclose attempts to use zinc particles or pellets as anodes. 
     The second way of mechanically refueling a metal-gas battery is far simpler than the first way. In the second way, the metallic anode is a rigid structure. When the metallic anode becomes spent, the anode is removed and a replacement anode is reinstalled into the cell. Because of its simplicity in theory, construction, maintenance and operation, the second of the two refueling methods is generally employed. U.S. Pat. Nos. 3,513,030, 5,203,526, 5,318,861, 5,366,822, 5,418,080, 5,447,805, 5,753,384, 5,904,999 and 6,057,053 all disclose various methods of mechanically refueling metal-gas cell batteries by changing out a rigid anode structure. Each of the patents listed in the immediately previous sentence are incorporated herein by this reference in their entireties. 
     One problem with such prior art metal-gas cell batteries is the difficulty with which the rigid anode structures are removed from the cell and inserted into the cell. In a conventional cell where the supporting structure is wholly rigid, clearances for the removal and reinsertion of such anodes are generally very small. The gas cathodes and separator sheets are often abraded during the removal and reinsertion of the anodes. U.S. Pat. Nos. 4,389,466 and 4,560,626 disclose an attempt to solve this problem. However, the total contact area between the cone-shaped current collectors and the metallic anodes used in the batteries disclosed in these patents is not sufficient for large currents. Moreover, pinpoints on the current collectors in the batteries disclosed in these patents often make the insertion and extraction of the metallic anodes very difficult. Another attempt to solve this problem is disclosed in U.S. Pat. No. 5,286,578. In this patent, it is suggested to make a metal-gas cell battery with a wholly flexible housing. However, such housing is fragile and cannot withstand repeated refueling. Other wholly flexible housing systems are disclosed in U.S. Pat. Nos. 5,415,949 and 5,650,241. Such housing systems are unduly complex and are therefore expensive to manufacture, maintain and operate. 
     U.S. Pat. Nos. 4,389,466 and 4,560,626 disclose using neoprene as the material to make a soft pocket. Although neoprene is well known in the art as the most alkaline-resistant rubber, due to the elasticity of the neoprene a soft pocket made with neoprene will be heavily deformed, just like a rubber balloon filled with water. This will result in fatigue of a neoprene-made soft pocket too early in the later refueling process. 
     U.S. Pat. No. 5,286,578 discloses a collapsible electrochemical cell using “a flexible plastic material” to satisfy its collapsible design. No detail of the flexible plastic material was disclosed, however. Similarly, U.S. Pat. No. 5,415,949 suggests using a pouch cathode, but no teaching is given on how to make the pouch. 
     Another problem with metal-air cell batteries, which are mechanically refueled by physical replacement of a rigid anode structure is the frequent leakage of the alkaline electrolyte. In most prior art designs, the housing of the metal-gas cell is usually opened at the top. The opening is sealed during operation by some form of elastic sealing element disposed between the cell housing and a protruding portion of the anode assembly. This protruding portion of the anode assembly is universally used in such designs for electrical connection to battery electrodes. Moreover, it is common to provide one or two small breathing holes along the uppermost portion of the cell proximate to the protruding portion of the anode. However, alkaline solution tends to creep up the anode and out of the cell along the protruding portion of the anode. Also, alkaline mist continuously escapes through the breathing holes. Such leakage and mist can cause rapid oxidation of the conductors above the anode and the air cathode. Oxidation dramatically increases the electrical resistance between the contacted surfaces and therefore results in a marked loss of battery power. Moreover, the continuing leaking of alkaline electrolyte and electrolyte mist makes the battery difficult to use in any kind of environment where oxidation of metallic items outside of the battery is a problem. Finally, any upset of the battery during handling or operation will cause copious leakage of electrolyte out of the battery. 
     Accordingly, there is a need for a metal-gas cell battery which is conveniently rechargeable by mechanical replacement of anode material and which avoids the aforementioned problems in the prior art. 
     SUMMARY OF INVENTION 
     The invention satisfies this need. The invention is a metal-gas cell storage battery comprising at least one battery cell. Each battery cell comprises (i) a first gas cathode disposed within a rigid planar first retaining structure, the first gas cathode being permeable to air but impermeable to liquids, the first gas cathode allowing the passage of gases into the cell, (ii) a second gas cathode disposed within a rigid planar second retaining structure, the second gas cathode being permeable to air but impermeable to liquids, the second gas cathode allowing the passage of gases into the cell, the second retaining structure being moveable with respect to the first retaining structure between a first retaining structure position wherein the first retaining structure is proximate to the second retaining structure and a second retaining structure position wherein the first retaining structure is spaced apart from the second retaining structure, the second gas cathode being electrically connected to the first gas cathode, (iii) a soft pocket disposed between the first gas cathode and the second gas cathode, the soft pocket having a flexible and planar first wall and a flexible and planar second wall, the first wall having a periphery and a central opening, the periphery of the first wall including a top edge, the second wall having a periphery and a central opening, the periphery of the second wall including a top edge, the periphery of the first wall connected to the periphery of the second wall except along the respective top edges, the periphery of the first wall being attached to the first retaining structure and the periphery of the second wall being attached to the second retaining structure, whereby the first retaining structure, the first gas cathode, the first wall, the second wall, the second retaining structure and the second gas cathode cooperate to define a liquid retaining soft pocket chamber having a soft pocket lower portion, a soft pocket upper portion and a soft pocket top opening defined between the top edges of the first and second walls, the soft pocket top opening being open in the second retaining structure position and tightly closed in the first retaining structure position, (iv) a soft pocket closing mechanism for securing the first and second retaining structures in the first retaining structure position, and (v) a metallic anode disposed within the soft pocket chamber. 
     The cell further comprises a positive first battery positive terminal electrically connected to the two gas cathodes and a negative second battery negative terminal electrically connected to the metallic anode. 
     In a typical embodiment of the invention, the gas cathode is an air cathode and the metallic anode is comprised substantially of metallic zinc. 
     In a preferred embodiment of the invention, the metallic anode is wholly disposed within the soft pocket chamber. 
     In another embodiment of the invention, the battery further comprises a second semi-permeable membrane disposed within the upper portion of the soft pocket chamber to reduce the pressure difference between the soft pocket chamber and the outside atmosphere. 
     In another embodiment of the invention, the soft pocket is made of a fabric reinforced membrane, such as vinylon or nylon fabric coated on one or both sides with neoprene, or of polypropylene or polyethylene with coating on one side of polypropylene or polyethylene, or of polypropylene or polyethylene with coating on a first side of polypropylene or polyethylene, and a coating on a second side of PVC. The fabric may be alkaline-resistant and selected from the group consisting of vinylon, nylon, polypropylene, polyethylene, ethylene propylene diene monomer, butyl rubber, ethylene-propylene copolymer, and chlorosulfonated polyethylene. 
     In a typical embodiment, the soft pocket closing mechanism is provided by one or more straps which circumscribe the one or more cells. Optionally, the soft pocket closing mechanism comprises one or more than one bolt and one or more than one nut. In one embodiment the soft pocket is comprises a molded integral piece w-shaped in cross section. 
     In a further embodiment of the invention, the periphery of the first wall is attached to the first retaining structure and the periphery of the second wall is attached to the second retaining structure, by mechanical force without glue. 
     The invention provides a metal-gas cell battery, such as a zinc-air battery, which is suitable for rapid refueling and which is sufficiently durable for hundreds of refueling operations. The invention also provides a metal-gas cell battery which does not leak electrolyte or electrolyte mist. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims and accompanying drawings where: 
     FIG. 1 is a perspective view of a metal-gas battery having features of the invention. 
     FIG. 2 is a perspective view of a metal-gas cell useable in the battery of FIG.  1 . 
     FIG. 3 is a perspective view of an anode useable in the battery of FIG.  1 . 
     FIG. 4 is an exploded view of the cell housing shown in FIG.  2 . 
     FIG. 5 is a perspective view of a pair of gas cathodes useable in the cell of FIG.  2 . 
     FIG. 6 is an exploded view of a pair of cells useable in the invention. 
     FIG. 7 is a perspective view of the pair of cells shown in FIG.  6 . 
     FIG. 8 is a cross-section view of two cells such as those illustrated in FIG.  7 . 
     FIG. 9 is a detailed view of the circled area in FIG.  8 . 
     FIG. 10 is a view of the unfolded soft pocket of FIG.  4 . 
     FIG. 11 is a cross-section view of one embodiment of a coated fabric useable in the soft pocket of FIG.  4 . 
     FIG. 12 is a cross-section view of a further embodiment of a coated fabric useable in the soft pocket of FIG.  4 . 
     FIG. 13 is a cross-section view of a preferred embodiment of a coated fabric useable in the soft pocket of FIG.  4 . 
     FIG. 14 is a cross-section view of a further embodiment of a coated fabric useable in the soft pocket of FIG.  4 . 
     FIG. 15 is a perspective view of another embodiment of the metal-gas battery having features of the invention. 
     FIG. 16 is a perspective view of a metal-gas cell useable in the battery of FIG.  15 . 
     FIG. 17 is a perspective view of an anode useable in the battery of FIG.  15 . 
     FIG. 18 is an exploded view of the cell housing shown in FIG.  16 . 
     FIG. 19 is a cross-section view of a portion of the frame of the cell housing of FIG.  18 . 
     FIG. 20 is a cross-section view of a portion of the frame of the cell housing of FIG.  18 . 
     FIG. 21 is a perspective view of a pair of gas cathode s useable in the cell of FIG.  16 . 
     FIG. 22 is an exploded view of a pair of cells useable in the invention. 
     FIG. 23 is a cross-section view of two cells such as those illustrated in FIG.  22 . 
     FIG. 24 is a perspective view of the pair of cells shown in FIG.  22 . 
     FIG. 25 is a front view of one of the pair of cells shown in FIG.  22 . 
     FIG. 26 is a cross-section view of the cell of FIG.  25 . 
     FIG. 27 is another cross-section view of the cell of FIG.  25 . 
     FIG. 28 is a cross-section view of the cell of FIG.  25 . 
     FIG. 29 is a close up view of the top of FIG.  26 . 
     FIG. 30 is a close up view of the bottom of FIG.  26 . 
     FIG. 31 is a close up view of the bottom of FIG.  23 . 
     FIG. 32 is a close up view of the top of FIG.  23 . 
    
    
     DETAILED DESCRIPTION 
     The following discussion describes in detail one embodiment of the invention and several variations of that embodiment. This discussion should not be construed, however, as limiting the invention to those particular embodiments. Practitioners skilled in the art will recognize numerous other embodiments as well. 
     The invention is a metal-gas cell battery  10  comprising at least one battery cell  12 , a positive first battery terminal  14  and a negative second battery terminal (not shown). Typically, the battery  10  of the invention comprises a plurality of identical battery cells  12 . In the discussion which follows, a typical embodiment is described wherein the battery  10  comprises a plurality of battery cells  12 , the reactive gas is oxygen, such as from air, and the anode material is zinc or similar material. 
     Each battery cell  12  comprises a first gas cathode  18 , a second gas cathode  20  and a soft pocket  22  disposed between the first gas cathode  18  and the second gas cathode  20 . The soft pocket  22  defines a soft pocket chamber  94 . Each battery cell  12  further comprises a metallic anode  24  disposed within the soft pocket chamber  94 . In a preferred embodiment, but not required, embodiment of the invention, the metallic anode  24  is wholly disposed within the soft pocket chamber  94 . 
     In the embodiment illustrated in FIG. 1, the battery of the invention  10  is a zinc-air battery comprising battery cells  12  connected in series. The battery  10  can comprise any number of battery cells  12 , depending upon what voltage is desired. 
     The battery  10  comprises a front cover plate  26  and a rear cover plate  28 . The cover plate  26  protects the outermost gas cathode  18  in the first battery cell and the cover plate  28  protects the outermost gas cathode  20  in the last battery cell. 
     FIGS. 2-9 illustrate a typical cell  12  useable in the battery  10 . Each first gas cathode  18  is a gas cathode disposed within a rigid planar first retaining structure  34 . The first gas cathode  18  is permeable to a reactive gas but impermeable to liquids. Where the reactive gas is atmospheric oxygen, the first gas cathode  18  allows the passage of oxygen from the atmosphere into the cell  12 . 
     The second gas cathode  20  is disposed within a rigid planar second retaining structure  38 . The second gas cathode  20  also is permeable to a reactive gas but impermeable to liquids. Where the reactive gas is atmospheric oxygen, the second gas cathode  20  allows the passage of oxygen from the atmosphere into the cell  12 . 
     The second retaining structure  38  is moveable with respect to the first retaining structure  34  between a first retaining structure position, wherein the first retaining structure  34  is proximate to the second retaining structure  38 , and a second retaining structure position wherein the first retaining structure  34  is spaced apart from the second retaining structure  38 . 
     Both the first gas cathode  18  and the second gas cathode  20  comprise a supporting lattice structure  40  which allows sufficient air flow through the gas cathodes  18  and  20 . 
     The soft pocket  22  has a soft pocket top opening  42  which is open in the second retaining structure position and which is tightly closed in the first retaining structure position. By “tightly closed,” it is meant that the soft pocket top opening  42  is sufficiently sealed to prevent the leakage of electrolyte or electrolyte fumes from the soft pocket chamber  94 . 
     As illustrated in FIG. 1, a soft pocket closing mechanism  44  is provided for securing the first and second retaining structures  34  and  38  in the first retaining structure position. In the embodiment illustrated in the drawings, the soft pocket closing mechanism  44  is provided by a pair of straps  46 . In other embodiments, a single strap  46  can be used. In still other embodiments, one or more clamps can be used. In still further other embodiments, screws protruding from the front cover plate  26  to the rear cover plate  28  can be used. An embodiment using screws is described below. 
     In the embodiment illustrated in the drawings, each of the straps  46  can be a conventional packing strap made from polypropylene or other suitable material. In the embodiment illustrated in FIG. 1, the opposed ends of each strap  46  are affixed to an H-shaped structure  48  having a pair of parallel vertical members  50  and a single lateral member  52 . Both the vertical members  50  and the lateral member  52  can be U-shaped in cross-section to provide structural rigidity. An H-shaped structure  48  is affixed to both the front cover plate  26  and the rear cover plate  28 , for example, by screws. 
     As can be seen from FIG. 1, both of the vertical members  50  on the H-shaped structure  48  comprise latch mechanisms  54  for tightening down on the pair of straps  46 . The lower end of each strap  46  is attached to a latch mechanism  54  at the lower end of one of the vertical members  50  by a pin  55 , and the upper ends of each strap  46  are attached to an attachment ring  56  disposed proximate to the upper end of one of the vertical members  50 . Each attachment ring  56  has a threaded hook  58  which can be adjustably threaded into the attachment ring  56  or threaded out of the attachment ring  56 . Each hook  58  is disposed such that it can be engaged by one of the two latch mechanisms  54 . 
     The H-shaped structure  48  on the rear cover plate  28 , however, has no latching mechanisms  54 , pin  55 , rings  56  or hooks  58 . On the rear cover plate  28 , each of the two straps  46  are retained within one of the U-shaped troughs  60  in the two vertical members  50 . 
     The positive first battery terminal  14  can be a male cone-shaped structure disposed in the front cover plate  26  as illustrated in FIG.  1 . The negative second battery terminal can be a corresponding female cone-shaped structure disposed in the rear cover plate  28 . The first battery terminal  14  is electrically connected to the two gas cathodes  18  and  20  which adjoins the first terminal  14 . The second battery terminal is electrically connected to the anode  24  which adjoins the second battery terminal. 
     Air for providing cooling and reactive oxygen to the battery  10  can be flowed through the battery  10  through gaps  62  disposed between the battery cells  12 . 
     In the embodiment illustrated in the drawings, the anode  24  is wholly disposed within the soft pocket  22 . FIG. 3 illustrates a typical anode  24  in detail. In the embodiment illustrated in FIG. 3, the anode  24  comprises an electrically conductive support structure  64  having a support structure base portion  66  and a support structure tab portion  68  disposed above the support structure base portion  66 . The support structure base portion  66  and the tab portion  68  can be made from any conductive material. Copper is a preferred material because of its low cost, rigidity and high conductivity. The support structure base portion  66  should be rigid enough to minimize damage or distortion during recycling, and should provide a large cross-sectional area to allow high current flow with minimal voltage drop. In the embodiment illustrated in FIG. 3, holes and slots  70  are disposed within the support structure base portion  66  to reduce the weight of the support structure  64  and to join the metal powder  71  (discussed immediately below) on both sides of the support structure base portion  66  into an integral whole. 
     Another embodiment of a typical anode is illustrated in FIG.  17 . 
     A metal powder  71 , such as zinc powder, is pressed onto the support structure base portion  66  to provide an anode base portion  72 . Preferably, the holes and slots  70  in the support structure base portion  66  are located and configured such that the electrical resistance between all particles of the zinc powder  71  and the support structure anode base portion  72  is nearly identical. 
     The anode base portion  72  is preferably planar and shaped to provide a large surface area. To facilitate the installation of the anode  24  into the soft pocket  22 , it is also preferable that the lowermost edge  74  of the anode base portion  72  be shorter than the length of the uppermost edge  76  of the anode base portion  72 . Thus, in a typical embodiment, the anode base portion  72  is trapezoidal in shape with the lowermost edge  74  of the anode base portion  72  being slightly shorter in length than the uppermost edge  76  of the anode base portion  72 . In such embodiments, it is also typical for the soft pocket  22  to have an equivalent shape. 
     The tab portion  68  of the support structure  64  provides a convenient handle which is useful in the installing and de-installing of the anode  24  from the soft pocket  22 . The tab portion  68  further provides an electrical connection means for the anode  24  as described below. In those preferred embodiments wherein the anode  24  is wholly disposed within the soft pocket  22  during operation, the tab portion  68  needs no sealing elements. 
     The anode base portion  72  is disposed within an enclosure bag  78  as illustrated in FIGS. 2 and 3. The enclosure bag  78  can be any suitable porous flexible material, such as a porous plastic membrane, woven fabric or non-woven fabric. The enclosure bag  78  is held in place around the anode base portion  72  by a pair of clips  80 . 
     FIG. 4 illustrates an exploded view of the battery cell  12  illustrated in FIG.  2 . As can be seen from this view, the soft pocket  22  comprises a flexible and planar first wall  82  and a flexible and planar second wall  84 . Both the first wall  82  and the second wall  84  have a periphery  86  and a central opening  88 . The periphery  86  of the first wall  82  includes a top edge  90  and the periphery  86  of the second wall  84  also comprises a top edge  92 . In the embodiment illustrated in the drawings, the periphery  86  of the first wall  82  further comprises left and right edges  83  and the periphery  86  of the second wall  84  further comprises left and right edges  83 . The periphery  86  of the first wall is attached to the first retaining structure  34  by adhesives or other similar attachment means. Similarly, the periphery  86  of the second wall  84  is attached to the second retaining structure  38  by adhesives or other similar attachment means. 
     FIG. 10 illustrates a preferred method for making the soft pocket  22 . A single sheet of the chosen material for the soft pocket  22  is punched to the shape shown in FIG. 10, having two openings  88 , periphery  86 , left and right edges  83 , top edge  90 , and top edge  92 . The material is folded along fold line  87 , and sealed along the left and right edges  83  by a suitable means to form the soft pocket  22 . Top edge  90  and top edge  92  are not sealed, so that soft pocket top opening  42  is created. Adhesive surfaces  89  are a preferred location for the adhesive to attach the periphery  86  of the first wall to the first retaining structure  34 , and the periphery  86  of the second wall  84  to the second retaining structure  38 . 
     By this design, the first retaining structure  34 , the first gas cathode  18 , the first wall  82 , the second wall  84 , the second retaining structure  38  and the second gas cathode  20  cooperate to enclose the soft pocket  22  so as to form the soft pocket chamber  94 . The soft pocket chamber  94  is open at the top opening  42  defined between the two top edges  90  and  92  of the first wall  82  and the second wall  84 . When electrolyte is disposed within the soft pocket chamber  94 , such electrolyte is in contact with the first gas cathode  18  via the central opening  88  in the first wall  82  and the electrolyte is similarly in contact with the second gas cathode  20  through the central opening  88  in the second wall  84 . 
     The planar walls  82  and  84  of the soft pocket  22  can be made from a plastic membrane or other suitable material. The first and second walls  82  and  84  of the soft pocket  22  can be made from polyethylene, polypropylene, nylon or other material capable of resisting deterioration from the electrolyte by having good alkaline-resistance. 
     Other materials which resist deterioration from the electrolyte and can be used include ethylene propylene diene monomer, butyl rubber, ethylene-propylene copolymer, and chlorosulfonated polyethylene. 
     A preferred material for making the planar walls  82  and  84  of the soft pocket  22  is fabric reinforced membrane. FIG. 11 shows a cross-section of a fabric reinforced membrane  150  useable in the present invention comprising fabric  154  having a first side  156 , a second side  158 , and coating  152 . In the embodiment shown in FIG. 11, fabric  154  is coated on the first side  156  with a coating  152  of neoprene. If the fabric  154  is netting, the neoprene may seep to the second side  158  of fabric  154 . In one embodiment having good alkaline resistance property, fabric  154  is made of vinylon. Nylon is one alternative choice for fabric  154 , but its alkaline-resistance property is less than vinylon. 
     The same adhesive used to sealed the left and right edges  83  to form the soft pocket  22  may be used to attach the periphery  86  of the first wall  82  to the first retaining structure  34 , and the periphery  86  of the second wall  84  to the second retaining structure  38 . When fabric  154  is coated on only one side, the uncoated side is the preferred side to attach to retaining structures  34  and  38 . When the coating  152  is neoprene, preferably the adhesive should be neoprene glue. 
     Another embodiment of fabric reinforced membrane  150  useable in the present invention is shown in FIG.  12 . In this further embodiment, fabric  154  is coated on both the first side  156  and second side  158  with coating  152 . When the coating  152  is neoprene, this construction provides very good adhesive property with the retaining structure  34  and retaining structure  38 , particularly when they are constructed of ABS, although it is more expensive. 
     A preferred embodiment of fabric reinforced membrane  150  useable in the present invention is shown in FIG.  13 . In this embodiment, fabric  154 ′ is coated on the first side  156  with coating  152 ′, wherein fabric  154 ′ is non-woven polypropylene or polyethylene, and coating  152 ′ is polypropylene or polyethylene. When non-woven polypropylene or polyethylene is used for fabric  154 ′ it is possible to heat seal the left and right edges  83  to form the soft pocket  22 , which is much easier than gluing neoprene. 
     Pure polypropylene or polyethylene is very difficult to be glued, due to the low surface energy of these non-polarized materials. In order to glue these kinds of materials, many methods have been developed to treat the surfaces before being glued together. None of these methods can guarantee no leakage in mass production. Due to its porous surface, when fabric  154 ′ is made of non-woven material the glue is absorbed and can reliably be attached to ABS plastic, even when the non-woven fabric is made of polyethylene fiber or polypropylene fiber. A non-woven fabric alone, however, cannot be used to make the soft pocket  22  because it will be permeable to liquid electrolyte. 
     Another embodiment of fabric reinforced membrane  150  useable in the present invention is shown in FIG.  14 . In this embodiment, fabric  154 ′ is coated on the first side  156  with coating  152 ′, and on the second side  158  with coating  152 ″, wherein fabric  154 ′ is non-woven polypropylene or polyethylene, coating  152 ′ is polypropylene or polyethylene, and coating  152 ″ is PVC. In this embodiment, the second side  158  with PVC coating  152 ″ is the side that is attached to retaining structures  34  and  38 . 
     FIG. 5 illustrates how the first gas cathode  18  and the second gas cathode  20  are disposed with respect to one another. The gas cathodes  18  and  20  can be any suitable gas cathodes known in the industry. Typical gas cathodes useable in the invention are manufactured by both Eltech Research Corporation and Alupower, Inc. As can be seen, both the first gas cathode  18  and the second gas cathode  20  comprise a wire mesh  96 . A laterally disposed current collector  98  is disposed along the top edges of each gas cathode  18  and  20 . In the embodiment illustrated in the drawings, two pairs of electrical contacts  100  extend from each current collector  98 . When the second retaining structure  38  is disposed in the first retaining structure position, each pair of electrical contacts  100  are in physical contact with one another. In this way, the two gas cathodes  18  and  20  are electrically connected to one another. 
     Another embodiment of first gas cathode  18  and second gas cathode  20  are shown in FIG.  21 . 
     FIG. 6 illustrates an exploded view of the assembly of two adjoining battery cells  12 . In the embodiment illustrated in FIG. 6, connecting blocks  102  are disposed at the top and the bottom to lock the second retaining structure  38  of a first battery cell  12 ′ to the first retaining structure  34  of a second battery cell  12 ″. The connecting blocks  102  have a female swallow-tailed slot  104  and the two adjoining retaining structures  34  and  38  combine to form a male swallow-tailed tenon  106  which is sized and dimensioned to be connected with the connecting blocks  102 . Also in FIG. 6 are illustrated a pair of side connecting bars  108 . Each connecting bar  108  has a number of swallow-tailed slots  104  which are sized and dimensioned to connect over swallow-tailed tenons  106  provided by the two adjoining retaining structures  34  and  38 . The connecting bar  108  has a plurality of openings  110  to provide the influx of air into the battery cells  12 . 
     FIG. 6 further illustrates the construction of a pair of interconnected slide fasteners which provide expansion restrainers  112  to prevent the expansion of each cell  12  beyond the second retaining structure position. 
     FIG. 7 illustrates a pair of fully assembled battery cells  12 ′ and  12 ″ which can be disposed adjacent to one another as illustrated in FIGS. 8 and 9. 
     FIG. 8 illustrates a cross-sectional view of a typical pair of battery cells  12  useable in the battery  10  of the invention. In FIG. 8, a first battery cell  12 ′ is disposed in abutment with a second battery cell  12 ″. Both battery cells  12 ′ and  12 ″ are shown in the second retaining structure position wherein the first retaining structure  34  of each cell  12  is spaced apart from the corresponding second retaining structure  38 . As illustrated in FIG. 8, the soft pocket top opening  42  of each cell  12  comprises the expansion restrainers  112  which limit the expansion of the soft pocket top opening  42  of each cell  12  beyond the second restraining structure position. Except for the expansion restrainers  112 , the soft pocket top opening  42  of each cell  12  is wholly open, so that the anode  24  within each cell  12  can be easily withdrawn from the soft pocket  22 , and so that a new anode  24  can be easily inserted into each soft pocket  22 . When the first and second retaining structures  34  and  38  are in the first retaining structure position, the soft pocket top opening  42  is tightly closed. 
     As further illustrated in FIG. 8, the battery  10  of the invention operates with an electrolyte  114  disposed within the soft pocket chamber  94 . The electrolyte  114  is typically an aqueous solution of potassium hydroxide, sodium hydroxide or sodium chloride. Excess electrolyte  114  for each cell  12  is stored within a collapsible electrolyte reservoir  116  disposed at the base of the soft pocket chamber  94 . The electrolyte  114  is disposed within a lower portion  118  of the soft pocket  22 . That portion of the soft pocket chamber  94  above the liquid level  120  of the electrolyte  114  is referred to herein as the upper portion  122  of the soft pocket chamber  94 . 
     In the embodiment illustrated in the drawings, the pressure balance within each cell  12  is provided by a semi-permeable membrane  124  disposed in the upper portion  122  of the soft pocket chamber  94 . Such semi-permeable membrane  124  can be made from PTFE or other suitable semi-permeable membrane material. Any gas generated inside the battery cell  12  flows through the semi-permeable membrane  124  to the atmosphere. Thus, the battery  10  of this embodiment requires no breathing holes in the cell housing or in the top of the anode  24  as is common in prior art metal-gas cell designs. By the design of this embodiment, liquid and mist within the cell  12  are wholly contained within the cell  12  and are not allowed to leak externally of the cell  12 . 
     FIG. 9 is a detailed view of a portion of the first battery cells  12  illustrated in FIG.  8 . As can be seen from FIG. 9, when the second retaining structures  38  are moved from the second retaining structure position (as illustrated in FIGS. 8 and 9) to the first retaining structure position (i.e., wherein the soft pocket top openings  22  are tightly closed), the tab portion  68  of the anode support structure  64  is firmly retained between the first restraining structure  34  and the second retaining structure  38 . Molded into the first retaining structure  34  is a U-shaped conductor element  128 , which contacts the tab portion  68  of the anode support structure  64 . The U-shaped conductor element  128  in the first retaining structure  34  of the first cell  12 ′ is electrically connected to the gas cathodes  18  and  20  of an adjoining cell  12 ″ (or to the negative second battery terminal if the first cell  12 ′ is an outermost cell). The U-shaped conductor element  128  in the first retaining structure  34  of the second cell  12 ″ is electrically connected to the gas cathodes  18  and  20  in the first cell  12 ′ by contact with a gas cathode conductor member  130  extending from the current collector  98  and disposed at the external surface  132  of the second retaining structure  38  of the first cell  12 ′. Where the gas cathode conductor member  130  is disposed within an outermost cell  12 , the gas cathode conductor member  130  is in direct electrical contact with the positive first battery terminal  14 . To facilitate the electrical contact between the U-shaped conductor element  128  and the gas cathode conductor member  130 , the contacting surfaces of the U-shaped conductor element  128  and the gas cathode conductor member  130  can be coated with silver or other suitable material to prevent possible oxidation of their respective contacting surfaces. 
     The second retaining structure  38  proximate to the tab portion  68  of an anode  24 , which is disposed within the soft pocket  22 , comprises a resilient retaining member  134 . Thus, when the second retaining structure  38  is in the first retaining structure position with respect to the first retaining structure  34 , the tab portion  68  of an anode  24  disposed within the soft pocket  22  is firmly retained between the second retaining structure  38  and the U-shaped conductor element  128 . 
     The U-shaped conductor element  128  also operates to conduct heat out of the battery cell  12 . In the embodiment illustrated in the drawings, the heat can be dissipated by air flowing by the inner surface  136  of the U-shaped conductor element  128  through lateral passageways  138  disposed within each retaining structure  34  and  16 . The electrical contacts  100  extending from the current collectors  98  also operate to conduct heat out of the battery cell  12 . The current collectors  98  are tightly pressed against the metallic mesh  96 , which comprises the surfaces of the gas cathodes  18  and  20 . Accordingly, the current collectors  98  conduct heat generated within the battery cell  12  to the airside surfaces of the gas cathodes  18  and  20 . 
     The invention provides a metal-gas cell battery, such as a zinc-air battery, which is suitable for rapid refueling and which is sufficiently durable for hundreds of refueling operations. The invention also provides a metal-gas cell battery, which does not leak electrolyte or electrolyte fumes. 
     A further embodiment of the invention is shown in FIG.  15 . As illustrated in FIG. 15, in this further embodiment a number of pairs of screws  30  and nuts  32  on the top and at the bottom are used to hold a plurality of the metal-gas cells together between cover plate  26  and cover plate  28  and two pi-shaped metal-fittings  16  as a single battery. The opening  42  of the soft pocket of each cell are held tightly closed by the screws  30  and the nuts  32 . As will be known to those skilled in the art with reference to this disclosure, it would be possible to construct a closing mechanism in this embodiment using one or more than one bolt and one or more than one nut. 
     In this further embodiment the positive first battery terminal  14  optionally can be a male cone-shaped structure or, or additionally optionally a red-colored cable with an eye-pin disposed in the front cover plate  26  as illustrated in FIG.  15 . The negative second battery terminal (not shown in FIG. 15) can optionally be a corresponding female cone-shaped structure or additionally optionally a black-colored cable with an eye-pin disposed in the rear cover plate  28 . The first battery terminal  14  is electrically connected to the first gas cathode  18  and the second gas cathode  20  which adjoins the first terminal  14 . The second battery terminal is electrically connected to the anode  24  which adjoins the second battery terminal. 
     FIG. 18 illustrates an exploded view of the battery cell  12  illustrated in FIG.  16 . The soft pocket  22  with w-shape in cross section as shown in FIG. 20 can be made of any kind of non-conductive soft material capable of resisting deterioration from the electrolyte, such as described above, or also ethylene-propylene diene monomer, butyl rubber, ethylene-propylene copolymer, chlorosulfonated polyethylene. Soft pocket chamber  94  is open at the top opening  42  defined between top edge  90  and top edge  92  of the first wall  82  and the second wall  84  as shown in FIG.  19 . 
     The grooves  178  and  180  on the soft pocket  22  shown in FIG. 20 should be wrapped on the periphery  186  of the first retaining structure  34  and the periphery  188  of the second retaining structure  38 . Referring to FIG. 26, FIG. 29, and FIG. 30, the four edges of both grooves  178  and  180  are securely wrapped on the four edges of the periphery  186  and periphery  188  and sealed by tightly pressed the metal-fittings  150 ,  152 ,  154  and  156  on the outer surfaces of the grooves  178  and  180 . 
     The further embodiment shown in FIG. 15 differs from the first described embodiment in that the two top edges  90  and  92  are thicker and more elastic than any kind of membrane, increasing reliable sealing. The top edges of the first retaining structure  34  and the second retaining structure  38  are whole flat surfaces, long enough to press against the whole length of the opening  42  of the soft pocket  22  completely. As can be seen from FIG. 18, FIG. 19, and FIG. 20, the soft pocket  22  is a molded integral piece w-shaped in cross section, making it unlikely to leak except through the contacting surfaces between the groove  178  and periphery  186  as well as the contacting surfaces between the groove  180  and periphery  188 . 
     In this embodiment, these contacting surfaces are reliably sealed by mechanical force created by the deformation of the metal-fittings  150 ,  152 ,  154  and  156 , and do not rely on any kind of glue. Further, as the natural mode of the soft pocket  22  is in opening state, the only compression force happens during operation. The pi-shaped metal-fittings are provided to create not only the contacting forces between electrical contacts  100  of the first gas cathode  18  and second gas cathode  20  and the contacting force of the tab  68  of the anode support structure  64  to the conducting surface  236  of the s-shaped conductor element  228  (shown in FIG.  26  and FIG.  29 ), but also the tightening force is evenly distributed along the whole length of the opening  42  of the soft pocket  22 , so that a more reliable sealing is obtained. 
     FIG.  22  and FIG. 23, FIG.  31  and FIG. 32, illustrate an exploded view of the assembly of two adjoining battery cells  12 . In the embodiment illustrated in FIG. 22, connecting blocks  102  are disposed at the top and the bottom to lock the second retaining structure  38  of a first battery cell  12 ′ to the first retaining structure  34  of a second battery cell  12 ″. As can be seen in FIG.  22  and FIG. 23, FIG.  31  and FIG. 32, the connecting blocks  102  have the pi-shaped slots, and will be pressed to form female swallow-tailed slots  104 , these slots  104  are sized and dimensioned to be fitted with the male swallow-tailed tenon  208  formed by the adjoining two metal-fittings  150  on the top of the cells  12 ′ and  12 ″, or metal-fittings  154  at the bottom of the cells  12 ′ and  12 ″. 
     FIG. 22 further illustrates the construction of a pair of interconnected slide fasteners which provide expansion restrainers  112  to prevent the expansion of each cell  12  beyond the second retaining structure position. 
     The four spacers  206  are used to provide the correct spacing between the adjoining two cells  12 ′ and  12 ″, so to allow the reactional air flows through the gap  62  between the cells. 
     FIG. 24 illustrates a pair of fully assembled battery cells  12 ′ and  12 ″ which can be disposed adjacent to one another as illustrated in FIGS.  22 . 
     Note that the contacting surface  238  is a part of a S-shaped conductor  228  shown in FIG.  26  and FIG.  29 . The other end surface  236  of the conductor  228  is tightly against the tab portion  68  of the anode structure  64 . The contacting surface  140  is on the extrusion part gas cathode conductor member  130  of the current collector  98 , which is directly wrapped on the top edge of the gas-cathode  20 . 
     There are one contacting surface  238  and one conducting surface  140  on a single battery cell, so that the said battery cells can be connected in series to obtain any desired voltage. 
     FIG. 25 illustrates a front view of a typical metal-gas cell  12  useable in the battery  10  of the invention. The shown places of the connecting blocks  102  and spacers  206  are one of the preferred embodiments. 
     FIG. 28 shows the construction of section C—C taken from FIG. 25, it clearly shows the soft pocket  22  in the operation mode. FIG. 27 shows the construction of section B—B taken from FIG.  25 . 
     Having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described herein below by the claims.