Tailored glycol-functionalized mixed-conductive polythiophene coatings enable stable zinc anodes

Abstract

Polymer protective layers possessing high flexibility and compatibility with substrates show potential to stabilize zinc anodes. However, inferior electronic or ionic conductivity and limited structural tunability restrain electrochemical reaction kinetics and targeted optimization of polymers. Here we present a mixed-conductive polythiophene coating, namely pgBTTT, with tailored glycol side chains. Compared with its alkyl chain counterpart pBTTT, pgBTTT exhibits superior electronic and ionic conductivity, and zincophilicity to facilitate uniform zinc deposition. Moreover, the strong coordination between the thiophene main chains of pgBTTT and zinc ions accelerates ion transport and diffusion through building exclusive channels. Correspondingly, the cycling stability of Zn‖Zn symmetric cells is improved with a small polarization voltage of 30 mV at 2 mA cm⁻². The full battery with the NH₄VO₄ cathode delivers a high specific capacity of 528 mA h g⁻¹ at 0.2 A g⁻¹ with a low capacity-fading rate of 0.0183% per cycle after 1000 cycles.