Thiophene Based Self‐Doped Conducting Polymers as Cathode for Aqueous Zinc‐Ion Battery

Abstract

AbstractSelf‐doping strategy is well‐known for enhanced ion transport in electrode materials. Herein we report self‐doped thiophene‐based conducting polymer (SDTP), where the dopant SO3− groups function as the hanging ion carrier mimicking a ‘pendulum hand’. It synergistically improves the battery performance, ideally mitigating the dissolution and the enhance ion diffusion kinetics. The diffusion coefficient was determined by three different techniques, i. e., electrochemical impedance spectroscopy (EIS), galvanostatic intermittent titration technique (GITT), and cyclic voltammetry at different sweep rates. The calculated diffusion coefficient for the SDTP was found to be much better than the neat thiophene polymer (NTP). The material was evaluated as a cathode for an aqueous zinc‐ion battery. The specific capacitance of the NTP was found to be 178 mAh g−1 at 50 mA g−1 current density. It was drastically reduced to 167, 118.2, and 83 mAh g−1 after the 5th, 10th, and 30th respective cycles. The polymer SDTP outperformed with a specific capacity of 274, 208, 159, 127, 108 mAh g−1 at current densities of 50, 100, 200, 300, 400 mA g−1. It exhibited good rate reversibility, and excellent rate stability with ∼99 % Coulombic efficiency in an over 4000 continuous cycles at 50 mA g−1 suggesting wise molecular engineering is necessary to improve battery performance.