Enhanced lifetime of the zinc–iodine batteries using hydrocarbon cation-exchange polymer-protected zinc anodes

Abstract

The zinc–iodine battery is a cost-effective, safe and scalable energy-storage device, which is nevertheless hindered by dendrite formation on the Zn anode and crossover of triiodide anions to the anode. We report that deposition of a fluorine-free cation-exchange polymer, sulfophenylated poly(phenylene)biphenyl (sPPB), onto the Zn anode serves as a protection layer that significantly suppresses Zn dendrite growth and restricts unwanted reaction of triiodide ions at the anode. sPPB-protected Zn anodes possess a relatively low charging polarization overpotential, which is attributed to a lower energy barrier for the desolvation of Zn ions, as supported by DFT calculations. sPPB-protected Zn anodes exhibit a >10× lifetime compared to bare Zn anodes in the Zn//Zn symmetric cells. Aqueous sPPB-protected zinc–iodine batteries deliver an initial capacity of 174 mA h g⁻¹ at 5C and retain 131 mA h g⁻¹ after 4000 cycles.