Evaluation of the electrochemical stability of graphite foams as current collectors for lead acid batteries

Graphite foams with high electrical and thermal conductivities, good mechanical strength, and low mass have been synthesized and evaluated as possible current collector materials to replace lead alloys for the development of lightweight lead acid batteries. Cyclic voltammetry and galvanostatic charge-discharge tests were performed on these foams prior to and after graphitization to evaluate their electrochemical properties. In the voltage range where the negative electrode of lead acid batteries operates, the graphite foam is electrochemically stable. However, in the voltage range of the positive electrode, the graphite foam is not electrochemically stable due to intercalation of sulfuric acid into graphite. For the positive electrode, the non-graphitized foam shows better electrochemical stability and warrants further study for use as a current collector. Preliminary charge/discharge characterization of these graphite and non-graphitized foams coated with a lead oxide battery paste supports these conclusions, although the paste formulation and coating process need to be improved for cycle life evaluation.