Separation Effect of Graphene Sheets with N, O Codoping and Molybdenum Clusters for Reversible Lithium–Iodine Batteries

Abstract

Lithium–iodine (Li–I2) batteries with ideal discharge potential plateau and abundant iodine resources have attracted considerable attention. However, the poor electrical conductivity of iodine with high solubility in organic electrolytes, and the Li dendrite issue have severely limited the practical application of Li–I2 batteries. Herein, this work demonstrates that the bifunctionalization of polypropylene (PP) separator with molybdenum clusters on N, O codoped graphene nanosheets (Mo‐rGO@PP) is efficient to promote the reversible redox reactions of polyiodides to suppress the shuttle effect, and enhance the Li affinity for the uniform Li plating/stripping. Typically, the Li symmetric battery assembled with Mo‐rGO@PP separator exhibits an ultralong lifespan of >2000 h with a low overpotential of <25 mV at 10 mA cm−2. With such a separation effect to effectively suppress the polyiodide shuttle and dendrite growth, the Li–I2 battery delivers a long cycle life of over 6000 cycles with a reversible capacity of 170 mAh g−1 at 10 C. With deep insights into the ion flux and redox regulation, this work demonstrates the promising advances via the separation effect for developing high‐performance redox batteries.