Reduced Temperature, High Power Thermal Battery Chemistry

Commercial lithium batteries (lithium-ion) utilize metal oxide based cathode materials to produce 4 volts per cell. In contrast, present lithium thermal batteries yield only 2 volts per cell. These new high voltage metal oxide materials are not stable in the hot molten chloride electrolytes of present thermal batteries and cannot be used. The large increase in cell voltages for thermal batteries offered by these new cathode materials can be realized by the use of molten nitrate electrolytes where these high voltage metal oxide cathode materials are stable. Examples of possible high voltage metal oxide based cathode materials include V2O5, PbO2, MnO2, LiCoO2, and LiMn2O4. The LMETB (Low Melting Electrolytes for Thermal Batteries) being developed by Dr. Mel Miles of Millennium Engineering allows for the use of molten nitrates and promises to deliver unprecedented thermal battery capability. Increasing the cell voltage for thermal batteries translates directly into large increases in energy densities and power densities. Molten nitrates offer lower operating temperatures of 150-350ºC versus the much higher operating temperatures of 400-550ºC for present thermal battery systems. Lower operating temperatures will allow the use of less insulating materials and gives the possibility of much longer thermal battery lifetimes following activation.