Metal-air cells comprising collapsible foam members and means for minimizing internal pressure buildup

A prismatic zinc-air cell comprising:

• a prismatic container having a top wall, a bottom wall, and side walls;
• one or more oxygen access openings disposed in the bottom wall of the container;
• an air cathode disposed in a layer extending parallel to the top and bottom walls of the container, substantially continuously between the side walls of the container, and having a first side and a second side, wherein the first side of the air cathode is in gaseous communication with the oxygen access openings;
• a separator disposed in a layer extending generally parallel to and coextensively with the air cathode and having a first side and a second side, wherein the first side of the separator is in electrolytic communication with the second side of the air cathode;
• a zinc anode including an electrolyte and disposed in a layer extending generally parallel to and coextensively with the separator and having a first side and a second side, wherein the first side of the zinc anode is in electrolytic communication with the second side of the separator;
• an expansion space within the container adjacent to the second side of the zinc anode and accommodating expansion of the zinc anode during discharge of the cells;
• a foam member generally occupying the expansion space and tending to oppose movement of the zinc anode away from the separator and to collapse upon expansion of the zinc anode during discharge, the foam member having a first side which is adjacent to the second side of the zinc anode;
• and
• one or more vent openings disposed in the top wall of the container in gaseous communication with the expansion space to minimize pressure increase within the container as the foam member collapses during discharge of the cell.

A prismatic zinc-air cell comprising:

• a prismatic container having one or more oxygen access openings;
• an air cathode disposed in the container in gaseous communication with the oxygen access openings;
• an anode assembly which comprises a rectangular anode frame having peripheral members, a separator mounted proximate to one end of the anode frame and extending substantially continuously between the anode frame peripheral members, whereby the anode frame and separator define a trough, and a zinc anode comprising zinc, an aqueous electrolyte, a gelling agent, and an inert, insoluble volume stabilizer present in an amount sufficient to enhance utilization of zinc in the anode and disposed in the trough in electrolytic communication with a first side of the separator, said anode assembly being is disposed in the container such that a second side of the separator is in electrolytic communication with the air cathode;
• an expansion space within the container adjacent to the zinc anode and accommodating expansion of the zinc anode during discharge of the cells;
• a foam member generally occupying the expansion space and tending to oppose movement of the zinc anode away from the separator and to collapse upon expansion of the zinc anode during discharge;
• and
• one or more vent openings disposed in the container in gaseous communication with the expansion space to minimize pressure increase within the container as the foam member collapses during discharge of the cell.