Electrochemical Synthesis of Polyindole and Its Evaluation for Rechargeable Battery Applications

The electrochemical synthesis of polyindole upon anodic oxidation of indole ( C 8 NH 7 ) in dichloromethane ( CH 2 Cl 2 ) containing 0.1 M tetrabutylammonium perchlorate (TBAP) is reported. The air‐stable polyindole films were obtained by sweeping the potential between −0.2 and 1.0 V vs Ag/AgCl as well as at constant potential (1.0 V vs Ag/AgCl) and constant current (0.2–0.3 mA/cm 2 ). The conductivities of such films were found to lie in the range 0.1–1 S cm −1 . The behavior of the polymer was studied by cyclic voltammetry and chronoamperometry. The electrochemically produced polyindole was studied as active material for secondary batteries in aqueous electrolyte. A Zn/1 M ZnSO 4 /polyindole cell gave a maximum capacity of 90 Ah kg −1 and an open‐circuit potential ( V oc ) of 1.45 V. This battery showed good reversibility and good coulombic efficiency.