Metal air cells are electrochemical cells where the oxygen in the air is the cathode material and a metal material is the anode material. Electrochemical cells of the button type are incorporated in many devices for producing electrical power. Button cells employing nonaqueous electrolytes and highly active metal anodes are particularly advantageous for certain uses while cells employing aqueous electrolytes are preferred for other uses. Metal air cells convert atmospheric oxygen to hydroxide in the air cathode, the hydroxide then migrating to the anode, where it causes the metal contained therein to oxidize. In many instances the preferred anode material is zinc. Zinc/air depolarized cells are typically in the form of miniature button cells which have particular utility as batteries for electronic hearing aids including programmable type hearing aids. Such miniature cells typically have a disk-like cylindrical shape of diameter between about 4 and 12 mm and a height between about 2 and 6 mm. Zinc air cells can also be produced in somewhat larger sizes having a cylindrical casing of size comparable to conventional AAAA, AAA, AA, C and D size alkaline cells. The miniature zinc/air button cell typically comprises an anode casing (anode cup), and a cathode casing (cathode cup). The anode casing and cathode casing typically each have a closed end and an open end. An electrical insulating material can be placed around the outside surface of the anode casing. After the necessary materials are inserted into the anode and cathode casings, the open end of the anode casing is typically inserted into the open end of the cathode casing and the cell sealed by crimping. Zinc/air button cells are generally constructed with an apertured cup which contains a hydrophobic layer of a material such as polytetrafluoroethylene (PTFE) adjacent the apertures to prevent electrolyte leakage but which permits air inflow. The apertures in the cup permit the influx of the cathode depolarizing air. The cup or container also contains the catalytic cathode and thereby comprises the positive terminal for the cell. To prevent gas from accumulating in the cell during cyclic charge/discharge operations, the negative electrode is usually designed to have a larger capacity than the positive electrode. Zinc/air cells are unique as compared to other button cells in that a void must be provided in the anode portion of the cell. The void is used to accommodate the substantial increase in volume during discharge which occurs, for example, when zinc oxide is produced as the discharge product of zinc anode. The need for this void comes from the sensitivity of the air cathode to pressure. Typical button-type alkaline electrochemical cells have a negative electrode (anode) with zinc or a zinc alloy as the active material and an alkaline electrolyte, such as potassium hydroxide. To reduce leakage, especially caused by gassing inside the cell during the electrochemical reaction, mercury has been added to the cell. Button cells on the market today employ a small amount of mercury. However, it has become apparent that mercury can be hazardous to the environment and to the health of humans and animals.

Implantable devices are becoming more and more complex and commonly include sophisticated data processing hardware such as microprocessors, memory devices, or other large scale integration (LSI) devices. A wide range of electronic devices are designed for surgical implantation into humans or animals. One common example is the cardiac pacemaker. Other examples of implantable devices include devices for stimulating or sensing portions of the brain, spinal cord, muscles, bones, nerves, glands or other body organs or tissues. Such devices are designed for transmitting signals to remote sensing devices. Implantable electrochemical cells are hermetically sealed using an insulating glass to separate the terminal pin from the case. Power sources of this type prevent internal components, such as the electrolyte, from coming into contact with body tissue or sensitive electrical components of the associated implantable medical device. An implantable electrochemical cell may include, for example, cells employing lithium as an anode material and polycarbon monofluoride as an active cathode material. Within such cells, a metal foil anode coated with lithium is provided in combination with polycarbon monofluoride formed on a current collector. A polymeric separator is positioned between the anode and the cathode thereby forming an electrode structure. The electrode structure is mounted within a cell housing which is flooded with a liquid non-aqueous electrolyte. Appropriate electrical contacts are provided to the anode and cathode.