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

Abstract

Polymer protective layers possessing high flexibility and compatibility with substrates show potentials to stabilize zinc anodes. However, inferior electronic or ionic conductivity, as well as 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 of pBTTT, pgBTTT exhibits superior electronic and ionic conductivity, and zincophilicity to guide uniform zinc deposition. Moreover, the strong coordination of thiophene main chains of pgBTTT with zinc ions accelerate ion transport and diffusion through building exclusive channels. Correspondingly, the cyclic stability of zinc-zinc symmetric cells is improved with a small polarization voltage of 30 mV at 2 mA cm-2. The full battery with NH4VO4 cathode delivers a high specific capacity of 528 mAh g-1 at 0.2 A g-1 with a low capacity-fading rate of 0.0183% per cycle after 1000 cycles.