Compounds for use as electrolyte in a non-aqueous redox battery are provided, including an N-substituted phenothiazine compound according to the formula: R′ is alkyl and R is selected from alkyl, aryl, alkylaryl, alkoxyaryl, alkylcarboxyl, arylcarbonyl, haloalkyl, perfluoroalkyl, glycol, polyether, haloaryl, a negative electrolyte, a polymerizable unit, and a polymer.