Study on the electrochemical properties of zinc/polyindole secondary battery

This study is intended to develop an aqueous zinc/polyindole secondary battery system. Polyindole, which is synthesized by chemical oxidation using ammonium peroxydisulfate as oxidants, is used as cathode active materials. Zn foil and ZnCl2 are used as anode active materials and the electrolytic solution, respectively. FTIR and NMR test are carried out to confirm the polymerization of indole and the chemical structure of polyindole. The performance of zinc/polyindole secondary battery system is evaluated in term of cyclic voltammogram, discharge capacity and durability test. The battery achieves 2.0 V during the charging process and shows about 80–60 Ah kg−1 discharge capacity at discharge current density of 200–1000 A m−2, respectively. The battery is successively charged and discharged at constant current densities, the discharge capacity density and energy density decreases only by 2.0% and 3.5% at 200th cycle, respectively. This result shows that the zinc/polyindole battery has the good characteristics of charge/discharge performance. With the development of the battery system, this sort of battery would be promising in future applications.

► Polyindole is synthesized using ammonium peroxydisulfate as oxidants.
► A secondary battery is constructed using polyindole as cathode and Zn foil as anode.
► The battery achieves about 80–60  Ah kg−1 capacity at different current density.
► The battery has good characteristics of charge/discharge performance.