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:
BACKGROUND OF INVENTION  
         [0001]    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.  
           [0002]    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.  
           [0003]    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.  
           [0004]    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.  
           [0005]    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 is comprised of 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.  
           [0006]    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.  
           [0007]    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.  
           [0008]    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.  
           [0009]    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  
         [0010]    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.  
           [0011]    The cell further comprises a positive first battery positive terminal electrically conected to the two gas cathodes and a negative second battery negative terminal electrically connected to the metallic anode.  
           [0012]    In a typical embodiment of the invention, the gas cathode is an air cathode and the metallic anode is comprised substantially of metallic zinc.  
           [0013]    In a preferred embodiment of the invention, the metallic anode is wholly disposed within the soft pocket chamber.  
           [0014]    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.  
           [0015]    In a typical embodiment, the soft pocket closing mechanism is provided by one or more straps which circumscribe the one or more cells.  
           [0016]    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  
       [0017]    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:  
         [0018]    [0018]FIG. 1 is a perspective view of a metal-gas battery having features of the invention;  
         [0019]    [0019]FIG. 2 is a perspective view of a metal-gas cell useable in the battery of FIG. 1;  
         [0020]    [0020]FIG. 3 is a perspective view of an anode useable in the battery of FIG. 1;  
         [0021]    [0021]FIG. 4 is an exploded view of the cell housing shown in FIG. 2;  
         [0022]    [0022]FIG. 5 is a perspective view of a pair of gas cathodes useable in the cell of FIG. 2;  
         [0023]    [0023]FIG. 6 is an exploded view of a pair of cells useable in the invention;  
         [0024]    [0024]FIG. 7 is a perspective view of the pair of cells shown in FIG. 6;  
         [0025]    [0025]FIG. 8 is a cross-section view of two cells such as those illustrated in FIG. 7; and  
         [0026]    [0026]FIG. 9 is a detailed view of the circled area in FIG. 8.  
     
    
     DETAILED DESCRIPTION  
       [0027]    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.  
         [0028]    The invention is a metal-gas cell battery  10  comprising at least one battery cell  20 , a positive first battery terminal  2  and a negative second battery terminal (not shown). Typically, the battery  10  of the invention comprises a plurality of identical battery cells  20 . In the discussion which follows, a typical embodiment is described wherein the battery  10  comprises a plurality of battery cells  20 , the reactive gas is oxygen, such as from air, and the anode material is zinc or similar material.  
         [0029]    Each battery cell  20  comprises a first gas cathode  4 , a second gas cathode  6  and a soft pocket  40  disposed between the first gas cathode  4  and the second gas cathode  6 . The soft pocket  40  defines a soft pocket chamber  60 . Each battery cell  20  further comprises a metallic anode  30  disposed within the soft pocket chamber  60 . In a preferred embodiment, but not required, embodiment of the invention, the metallic anode  30  is wholly disposed within the soft pocket chamber  60 .  
         [0030]    In the embodiment illustrated in FIG. 1, the battery of the invention  10  is a zinc-air battery comprising battery cells  20  connected in series. The battery  10  can comprise any number of battery cells  20 , depending upon what voltage is desired.  
         [0031]    The battery  10  comprises a front cover plate  8  and a rear cover plate  12 . The cover plate  8  protects the outermost gas cathode  4  in the first battery cell and the cover plate  12  protects the outermost gas cathode  6  in the last battery cell.  
         [0032]    FIGS.  2 - 9  illustrate a typical cell  20  useable in the battery  10 . Each first gas cathode  4  is a gas cathode disposed within a rigid planar first retaining structure  14 . The first gas cathode  4  is permeable to a reactive gas but impermeable to liquids. Where the reactive gas is atmospheric oxygen, the first gas cathode  4  allows the passage of oxygen from the atmosphere into the cell  20 .  
         [0033]    The second gas cathode  6  is disposed within a rigid planar second retaining structure  16 . The second gas cathode  6  also is permeable to a reactive gas but impermeable to liquids. Where the reactive gas is atmospheric oxygen, the second gas cathode  6  allows the passage of oxygen from the atmosphere into the cell  20 .  
         [0034]    The second retaining structure  16  is moveable with respect to the first retaining structure  14  between a first retaining structure position, wherein the first retaining structure  14  is proximate to the second retaining structure  16 , and a second retaining structure position wherein the first retaining structure  14  is spaced apart from the second retaining structure  16 .  
         [0035]    Both the first gas cathode  4  and the second gas cathode  6  comprise a supporting lattice structure  18  which allows sufficient air flow through the gas cathodes  4  and  6 .  
         [0036]    The soft pocket  40  has a soft pocket top opening  22  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  22  is sufficiently sealed to prevent the leakage of electrolyte or electrolyte fumes from the soft pocket chamber  60 .  
         [0037]    As illustrated in FIG. 1, a soft pocket closing mechanism  24  is provided for securing the first and second retaining structures  14  and  16  in the first retaining structure position. In the embodiment illustrated in the drawings, the soft pocket closing mechanism  24  is provided by a pair of straps  26 . In other embodiments, a single strap  26  can be used. In still other embodiments, one or more clamps can be used. In still further other embodiments, screws (not shown) protruding from the front cover plate  8  to the rear cover plate  12  can be used.  
         [0038]    In the embodiment illustrated in the drawings, each of the straps  26  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  26  are affixed to an H-shaped structure  28  having a pair of parallel vertical members  32  and a single lateral member  34 . Both the vertical members  32  and the lateral member  34  can be U-shaped in cross-section to provide structural rigidity. An H-shaped structure  28  is affixed to both the front cover plate  8  and the rear cover plate  12 , for example, by screws.  
         [0039]    As can be seen from FIG. 1, both of the vertical members  32  on the H-shaped structure  28  comprise latch mechanisms  36  for tightening down on the pair of straps  26 . The lower end of each strap  26  is attached to a latch mechanism  36  at the lower end of one of the vertical members  32  by a pin  38 , and the upper ends of each strap  26  are attached to an attachment ring  42  disposed proximate to the upper end of one of the vertical members  32 . Each attachment ring  42  has a threaded hook  44  which can be adjustably threaded into the attachment ring  42  or threaded out of the attachment ring  42 . Each hook  44  is disposed such that it can be engaged by one of the two latch mechanisms  36 .  
         [0040]    The H-shaped structure  28  on the rear cover plate  12 , however, has no latching mechanisms  36 , pin  38 , rings  42  or hooks  44 . On the rear cover plate  12 , each of the two straps  26  are retained within one of the U-shaped troughs  46  in the two vertical elements  32 .  
         [0041]    The positive first battery terminal  2  can be a male cone-shaped structure disposed in the front cover plate  8  as illustrated in FIG. 1. The negative second battery terminal can be a corresponding female cone-shaped structure disposed in the rear cover plate  12 . The first battery terminal  2  is electrically connected to the two gas cathodes  4  and  6  which adjoins the first terminal  2 . The second battery terminal is electrically connected to the anode  30  which adjoins the second battery terminal.  
         [0042]    Air for providing cooling and reactive oxygen to the battery  10  can be flowed through the battery  10  through gaps  52  disposed between the battery cells  20 .  
         [0043]    In the embodiment illustrated in the drawings, the anode  30  is wholly disposed within the soft pocket  40 . FIG. 3 illustrates a typical anode  30  in detail. In the embodiment illustrated in FIG. 3, the anode  30  comprises an electrically conductive support structure  54  having a support structure base portion  56  and a support structure tab portion  58  disposed above the support structure base portion  56 . The support structure base portion  56  and the tab portion  58  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  56  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  62  are disposed within the support structure base portion  56  to reduce the weight of the support structure  54  and to join the metal powder  64  (discussed immediately below) on both sides of the support structure base portion  56  into an integral whole.  
         [0044]    A metal powder  64 , such as zinc powder, is pressed onto the support structure base portion  56  to provide an anode base portion  66 . Preferably, the holes and slots  62  in the support structure base portion  56  are located and configured such that the electrical resistance between all particles of the zinc powder  64  and the support structure anode base portion  66  is nearly identical.  
         [0045]    The anode base portion  66  is preferably planar and shaped to provide a large surface area. To facilitate the installation of the anode  30  into the soft pocket  40 , it is also preferable that the lowermost edge  68  of the anode base portion  66  be shorter than the length of the uppermost edge  72  of the anode base portion  66 . Thus, in a typical embodiment, the anode base portion  66  is trapezoidal in shape with the lowermost edge  68  of the anode base portion  66  being slightly shorter in length than the uppermost edge  72  of the anode base portion  66 . In such embodiments, it is also typical for the soft pocket  40  to have an equivalent shape.  
         [0046]    The tab portion  58  of the support structure  54  provides a convenient handle which is useful in the installing and de-installing of the anode  30  from the soft pocket  40 . The tab portion  58  further provides an electrical connection means for the anode  30  as described below. In those preferred embodiments wherein the anode  30  is wholly disposed within the soft pocket  40  during operation, the tab portion  58  needs no sealing elements.  
         [0047]    The anode base portion  66  is disposed within an enclosure bag  60  as illustrated in FIGS. 2 and 3. The enclosure bag  60  can be any suitable porous flexible material, such as a porous plastic membrane, woven fabric or non-woven fabric. The enclosure bag  60  is held in place around the anode base portion  66  by a pair of clips  74 .  
         [0048]    [0048]FIG. 4 illustrates an exploded view of the battery cell  20  illustrated in FIG. 2. As can be seen from this view, the soft pocket  40  comprises a flexible and planar first wall  76  and a flexible and planar second wall  78 . Both the first wall  76  and the second wall  78  have a periphery  85  and a central opening  84 . The periphery  85  of the first wall  76  includes a top edge  86  and the periphery  85  of the second wall  78  also comprises a top edge  88 . In the embodiment illustrated in the drawings, the periphery  85  of the first wall  96  further comprises left right edges  82  and the periphery  85  of the second wall  78  further comprises a left and right edges  82 . The periphery  85  of the first wall is attached to the first retaining structure  14  by adhesives or other similar attachment means. Similarly, the periphery  85  of the second wall  78  is attached to the second retaining structure  16  by adhesives or other similar attachment means. By this design, the first retaining structure  14 , the first gas cathode  4 , the first wall  76 , the second wall  78 , the second retaining structure  16  and the second gas cathode  6  cooperate to enclose the soft pocket  40  so as to form the soft pocket chamber  60 . The soft pocket chamber  60  is open at the top opening  22  defined between the two top edges  86  and  88  of the first wall  76  and the second wall  78 . When electrolyte is disposed within the soft pocket chamber  60 , such electrolyte is in contact with the first gas cathode  4  via the central opening  84  in the first wall  76  and the electrolyte is similarly in contact with the second gas cathode  6  through the central opening  84  in the second wall  78 .  
         [0049]    The planar walls  76  and  78  of the soft pocket  40  can be made from a plastic membrane or other suitable material. The first and second walls  76  and  78  of the soft pocket  40  can be made from polyethylene, polypropylene, nylon or other material capable of resisting deterioration from the electrolyte.  
         [0050]    [0050]FIG. 5 illustrates how the first gas cathode  4  and the second gas cathode  6  are disposed with respect to one another. The gas cathodes  4  and  6  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  4  and the second gas cathode  6  comprise a wire mesh  144 . A laterally disposed current collector  96  is disposed along the top edges of each gas cathode  4  and  6 . In the embodiment illustrated in the drawings, two pairs of electrical contacts  98  extend from each current collector  96 . When the second retaining structure  16  is disposed in the first retaining structure position, each pair of electrical contacts  98  are in physical contact with one another. In this way, the two gas cathodes  4  and  6  are electrically connected to one another.  
         [0051]    [0051]FIG. 6 illustrates an exploded view of the assembly of two adjoining battery cells  20 . In the embodiment illustrated in FIG. 6, connecting blocks  102  are disposed at the top and the bottom to lock the second retaining structure  16  of a first battery cell  20 ′ to the first retaining structure  14  of a second battery cell  20 ″. The connecting blocks  102  have a female swallow-tailed slot  104  and the two adjoining retaining structures  14  and  16  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  14  and  16 . The connecting bar  108  has a plurality of openings  146  to provide the influx of air into the battery cells  20 .  
         [0052]    [0052]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  20  beyond the second retaining structure position.  
         [0053]    [0053]FIG. 7 illustrates a pair of fully assembled battery cells  20  which can be disposed adjacent to one another as illustrated in FIGS. 8 and 9.  
         [0054]    [0054]FIG. 8 illustrates a cross-sectional view of a typical pair of battery cells  20  useable in the battery  10  of the invention. In FIG. 8, a first battery cell  20 ′ is disposed in abutment with a second battery cell  20 ″. Both battery cells  20 ′ and  20 ″ are shown in the second retaining structure position wherein the first retaining structure  14  of each cell  20  is spaced apart from the corresponding second retaining structure  16 . As illustrated in FIG. 8, the soft pocket top opening  22  of each cell  20  comprises the expansion restrainers  112  which limit the expansion of the soft pocket top opening  22  of each cell  20  beyond the second restraining structure position. Except for the expansion restrainers  112 , the soft pocket top opening  22  of each cell  20  is wholly open, so that the anode  30  within each cell  20  can be easily withdrawn from the soft pocket  40 , and so that a new anode  30  can be easily inserted into each soft pocket  40 . When the first and second retaining structures  14  and  16  are in the first retaining structure position, the soft pocket top opening  22  is tightly closed.  
         [0055]    As further illustrated in FIG. 8, the battery  10  of the invention operates with an electrolyte  114  disposed within the soft pocket chamber  60 . The electrolyte  114  is typically an aqueous solution of potassium hydroxide, sodium hydroxide or sodium chloride. Excess electrolyte  114  for each cell  20  is stored within a collapsible electrolyte reservoir  116  disposed at the base of the soft pocket chamber  76 . The electrolyte  114  is disposed within a lower portion  118  of the soft pocket  40 . That portion of the soft pocket chamber  60  above the liquid level  122  of the electrolyte  114  is referred to herein as the upper portion  122  of the soft pocket chamber  60 .  
         [0056]    In the embodiment illustrated in the drawings, the pressure balance within each cell  20  is provided by a semi-permeable membrane  126  disposed in the upper portion  122  of the soft pocket chamber  60 . Such semi-permeable membrane  126  can be made from PTFE or other suitable semi-permeable membrane material. Any gas generated inside the battery cell  20  flows through the semi-permeable membrane  126  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  30  as is common in prior art metal-gas cell designs. By the design of this embodiment, liquid and mist within the cell  20  are wholly contained within the cell  20  and are not allowed to leak externally of the cell  20 .  
         [0057]    [0057]FIG. 9 is a detailed view of a portion of the first battery cells  20  illustrated in FIG. 8. As can be seen from FIG. 9, when the second retaining structures  16  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 S 8  of the anode support structure  54  is firmly retained between the first restraining structure  14  and the second retaining structure  16 . Molded into the first retaining structure  14  is a U-shaped conductor element  128 , which contacts the tab portion  58  of the anode support structure  54 . The U-shaped conductor element  128  in the first retaining structure  14  of the first cell  20 ′ is electrically connected to the gas cathodes  4  and  6  of an adjoining cell  20 ″ (or to the negative second battery terminal if the first cell  20 ′ is an outermost cell). The U-shaped conductor element  128  in the first retaining structure  14  of the second cell  20 ″ is electrically connected to the gas cathodes  4  and  6  in the first cell  20 ′ by contact with a gas cathode conductor member  132  extending from the current collector  96  and disposed at the external surface  134  of the second retaining structure  16  of the first cell  20 ′. Where the gas cathode conductor member  132  is disposed within an outermost cell  20 , the gas cathode conductor member  132  is in direct electrical contact with the positive first battery terminal  2 . To facilitate the electrical contact between the U-shaped conductor element  128  and the gas cathode conductor member  132 , the contacting surfaces of the U-shaped conductor element  128  and the gas cathode conductor member  132  can be coated with silver or other suitable material to prevent possible oxidation of their respective contacting surfaces.  
         [0058]    The second retaining structure  16  proximate to the tab portion  58  of an anode  30 , which is disposed within the soft pocket  40 , comprises a resilient retaining member  134 . Thus, when the second retaining structure  16  is in the first retaining structure position with respect to the first retaining structure  14 , the tab portion  58  of an anode  30  disposed within the soft pocket  40  is firmly retained between the second retaining structure  16  and the U-shaped conductor element  128 .  
         [0059]    The U-shaped conductor element  128  also operates to conduct heat out of the battery cell  20 . In the embodiment illustrated in the drawings, the heat can be dissipated by air flowing by the inner surface  138  of the U-shaped conductor element  128  through lateral passageways  142  disposed within each retaining structure  14  and  16 . The electrical contacts  98  extending from the current collectors  96  also operate to conduct heat out of the battery cell  20 . The current collectors  96  are tightly pressed against the metallic mesh  144 , which comprises the surfaces of the gas cathodes  4  and  6 . Accordingly, the current collectors  96  conduct heat generated within the battery cell  20  to the airside surfaces of the gas cathodes  4  and  6 .  
         [0060]    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.  
         [0061]    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.