Electrolyte formulations for use in biocompatible batteries or batteries for a biomedical device such as an electroactive contact lens are described. The electrolyte formulations involve liquid or gelled electrolytes formulated to optimize biocompatibility, electrical performance, and physical performance. As a first example an electrolyte solution might comprise ZnCl2 and indium acetate in water with optionnaly a surfactant. As a second example a gelled electrolyte might comprise calcium nitrate, carboxymethylcellulose and silicon dioxide.
