Enhanced carbon host with N-reinforced S-sites to catalyze rapid iodine conversion kinetics for Zn-I2 battery

Abstract

Aqueous zinc-iodine (Zn-I2) battery is a promising energy storage system in the establishment of a low-carbon, clean society, but they are limited by unsatisfied reversible capacity and poor cycle life. Ultimately, this is due to the poor iodine conversion kinetics and the shuttle effect of the intermediate polyiodide. Herein, a N-reinforced S-site carbon host (labeled as NS-YP80F) is designed to resolve these issues. DFT calculation shows that the electrochemical activity of the NS-YP80F with abundant S-site can be further enhanced by introducing N-atom at the original S-site. The synergistic effect of N-reinforced S-site carbon host cannot only enhance the adsorption of polyiodide to avoid the shuttle effect, but also induce the smooth conversion of iodine through enhanced catalytic mechanism. Consequently, the Zn-I2 battery with NS-YP80F@I2 cathode shows high reversible capacity (127 mAh g−1 at 1C) and stable cycling lifespan (15,000 cycles) with a high current density of 50 C. This strategy achieved a breakthrough in the electrochemical activity of the heteroatom doping carbon hosts, and provided a simple and effective solution for optimizing the performance of Zn-I2 battery.