High cycling stability of zinc-anode/conducting polymer rechargeable battery with non-aqueous electrolyte

Abstract

A non-aqueous zinc–polyaniline secondary battery was fabricated with polyaniline Emeraldine base as cathode and zinc metal as anode in an electrolyte consisting of 0.3 M zinc-bis(trifluoromethyl-sulfonyl)imide Zn(TFSI)2 dissolved in propylene carbonate. We observed that the formation of the battery required a prerequisite condition to stabilize the interfaces in order to maintain a stable capacity. The battery suffered from Zn dissolution which induces a competition between concurrent Zn dissolution and plating when the battery is in charge mode, and thus inefficient cycles are obtained. The capacity and coulombic efficiency of the battery depends on the charge–discharge rates. We propose cycling protocols at different rates to determine the steady-state rates of competing reactions. When the cell is cycled at ≥1 C rate, the coulombic efficiency improves. The maximum capacity and energy densities of the battery are 148 mAhg−1 and 127 mWhg−1, respectively for discharge at C/2. The battery was successively charged/discharged at constant current densities (1C rate), and high cycling stability was obtained for more than 1700 cycles at 99.8% efficiency. Zinc dissolution and self discharge of the battery were investigated after 24 h of standby. The investigation showed that the battery experiences a severe self-discharge of 48% per day.