Zeolite-modified chloranil (2,3,5,6-tetrachloro-p-benzoquinone) exhibits improved performance as a battery negative in comparison with an unmodified chloranil negative. A zinc-chloranil secondary battery incorporating the zeolite-modified negative yields 107 cycles in contrast to 50 cycles in the absence of the zeolite. The charge-discharge characteristics and cyclic voltammetric and IR spectral analysis are presented.