INVESTIGATIONS ON AN AQUEOUS LITHIUM SECONDARY CELL

The deposition and stripping of lithium from different substrates has been investigated in saturated aqueous solutions of LiCl/LiOH to assess the possibility of developing a secondary lithium battery with high energy density and high power density, and based on water as a solvent. On mercury electrodes, a low catalytic activity for hydrogen evolution is observed, together with a positive shift in potential on amalgamation. This means that lithium deposition is the predominant electrode reaction at negative potentials. Indeed, the lithium charge recovery at a mercury anode is 98.5%. Other practical anode materials, however, fail to give a charge recovery anywhere close to this value. Anode materials investigated include metals that alloy with lithium and materials that form lithium insertion compounds. Manganese dioxide appears to be an effective cathode material for a battery using saturated LiCl/LiOH as the electrolyte. The positive electrode reaction at MnO2 in this medium is shown to be lithium insertion rather than protonation, and acceptable rechargeability is observed.