Anti‐Self‐Discharge Capability of Zn‐Halogen Batteries Through an Entrapment‐Adsorption‐Catalysis Strategy Built Upon Separator

Abstract Aqueous Zn‐halogen batteries (Zn‐I2/Br2) suffer from grievous self‐discharge behavior, resulting in irreversible loss of active cathode material and severe corrosion of zinc anode, which ultimately leads to rapid battery failure. Herein, an entrapment‐adsorption‐catalysis strategy is reported, leveraging Zn─Mn atom pairs‐modified glass fiber separator (designated as ZnMn‐NC/GF), to effectively mitigate the self‐discharge phenomenon. The in situ Raman and UV experiments, along with theoretical calculations, confirmed the single‐atom Mn sites are responsible for polyiodides adsorption, while Zn─Mn atom pairs facilitated the conversion of reaction intermediates. As a result, the utilization rate of cathode active species is enhanced through this ZnMn‐NC/GF separator. The fully charged Zn‐I2 battery assembled with ZnMn‐NC/GF maintained a Coulombic efficiency (CE) of 90.1% after being left for 120 h, as well as a capacity retention rate of 95.3% after 30000 cycles at a current density of 5 A g−1. Additionally, the Zn‐Br2 battery designed with ZnMn‐NC/GF separator can withstand more serious self‐discharge problems of bromine species, with an average discharge voltage platform of 1.75 V at 0.5 A g−1. The self‐discharge problem of aqueous Zn‐halogen batteries is significantly suppressed by this entrapment‐adsorption‐catalysis strategy, which can serve as a crucial reference for the advancement of high‐performance aqueous Zn‐halogen batteries.