Our objective is to improve the safety of lithium/sulfur dioxide (tetrachloroaluminate) rechargeable cells. Recent work at our laboratory showed that sulfur dioxide solutions of tetrachloro aluminate salts contain hydrolysis products which are difficult to eliminate, even if the aluminum chloride used has first been carefully purified. We have suspected that hydrolysis products contribute to the instability of cells during charging, and propose three methods to eliminate proton-containing impurities. We also propose to investigate whether replacing the teflon binder in the positive electrode with an acid resistant elastomer that will not react as violently with lithium might reduce the incidence of runaway reactions during charging. The test vehicle is to be a hermetically sealed aa size cell previously engineered for use in the study of lithium rechargeable systems.
