Enhanced Adsorption-Catalytic Conversion of Iodine Species by Amorphous CoP@C Host Materials for Zinc Iodine Battery.

Abstract

Extensive applications of aqueous zinc iodine batteries (AZIBs) are hindered by the sluggish iodine redox reaction and shuttling effect of the polyiodides. In this study, amorphous cobalt phosphide grown on activated carbon (ACoP@C) was proposed as an iodine host material to address these issues. Specifically, the ACoP@C can offer numerous iodine anchoring sites and proposed electrocatalytic properties, which significantly reduce shuttling and enhance the conversion kinetics of iodine species. Additionally, the conductive carbon substrate with abundant porous channels facilitates rapid and continuous long-range electron and ion transport. As a result, the ACoP@C/I₂ cathode demonstrated high capacities of 173.7 mA h g^-1 at 0.1 A g^-1 and 99.0 mA h g^-1 at 5.0 A g^-1, along with a stable long cycle capacity of 80.0 mA h g^-1 over 850 cycles at 1.0 A g^-1. Moreover, UV spectroscopy and electrochemical measurements revealed enhanced redox mechanisms of the iodine species. This study provides valuable insights for the design and development of efficient amorphous catalyst materials for future AZIBs.