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 Pr 3+ additive in AZMBs. Proton conduction is deeply understood in this quasi‐solid electrolyte. Pr 3+ additive not only dominates the proton conduction kinetics, but also regulates the reversible manganese interfacial deposition. As a result, the Cu@Zn||α‐MnO 2 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.