Promoting Zinc Plating and Silencing the Hydrogen Evolution Reaction through Spatial Decoupling for Durable Aqueous...

An aqueous Zn-ion battery (AZIB), with its safety and cost benefits, is a promising technology for grid-scale energy storage applications. However, side reactions, such as the hydrogen evolution reaction (HER), occur synchronously with Zn plating, causing anode irreversibility and constituting a fundamental limitation of AZIBs. Herein, we propose a spatial decoupling strategy, using post-transition metal halide as an electrolyte additive to construct in situ microheterogeneity at the anode interface so as to decouple such synchronicity, promoting Zn plating while silencing the HER with solvating H₂O "hopping" to the anchored halide anion. The work function of post-transitional metals and the polarizability of halide anions are key features in constructing such fast Zn²⁺ conducting channels. As a result, using InBr₃ enhances the accumulated capacity of a Zn||Zn cell by 64 times from 0.074 to 4.8 Ah cm^-2, the cycle life of a V₂O₅||Zn battery by 100 times from 10 to >1000 cycles, and the stable capacity of a Mn₂V₂O₇||Zn battery by 70% from 83 to 141 mAh g^-1. We further introduce a feature matrix predicting efficient post-transitional metal cation and halide anion combinations to enhance the reversibility of metal deposition-dissolution reactions. This framework can be generalized to advance other battery chemistries both practically and mechanistically.