Charge-discharge characteristics of polyvinylpyridinium hydrobromide perbromide-carbon paste electrodes

Abstract

The work mainly focuses on the electrode characteristics of poly(4-vinylpyridine)-carbon paste composites in aqueous Br− electrolytes. The reversible driving of the Br−/Br3− couple ‘inside’ the polymer is initially much faster in KBr than in ZnBr2. However, after repeated cycling, the paste electrodes are also conditioned to ZnBr2, so that charging/discharging of bromine can be carried out with ∼1 A dm−2 applied without causing excessive polarization. The possible use in secondary Zn/Br2 batteries of a poly(4-vinylpyridine) solid matrix, which both complexes the halogen and collects the current, is a distinct possibility. This view is supported by the low self-discharge tested for poly(4-vinylpyridinium hydrobromide perbromide) which compares favourably with the previous state-of-the-art.