Effective Proton Conduction in Quasi‐Solid Zinc‐Manganese Batteries via Constructing Highly Connected Transfer Pathways

Abstract

Elusive ion behaviors in aqueous electrolyte remain a challenge to break through the practicality of aqueous zinc-manganese batteries (AZMBs), a promising candidate for safe grid-scale energy storage systems. The proposed electrolyte strategies for this issue most ignore the prominent role of proton conduction, which greatly affects the operation stability of AZMBs. Here we report a water-poor quasi-solid electrolyte with efficient proton transfer pathways based on the large-space interlayer of montmorillonite and strong-hydration Pr³⁺ additive in AZMBs. Proton conduction is deeply understood in this quasi-solid electrolyte. Pr³⁺ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α-MnO₂ cell could achieve a high specific capacity of 433 mAh g^-1 at 0.4 mA cm^-2 and an excellent stability up to 800 cycles with a capacity retention of 92.2 % at 0.8 mA cm^-2 in such water-poor quasi-solid electrolyte for the first time. Ah-scale pouch cell with mass loading of 15.19 mg cm^-2 sustains 100 cycles after initial activation, which is much better than its counterparts. Our work provides a new path for the development of zinc metal batteries with good sustainability and practicality.