Moderate hydrogen bond network via in situ dissolved interfacial cation solvation for highly active aqueous zinc–manganese batteries

Abstract

Aqueous zinc–manganese batteries (AZMBs) are regarded as strong contenders for next-generation energy storage systems due to their high safety and low cost. Due to the complex MnO₂/Mn²⁺ deposition/dissolution mechanism, however, they face challenges arising from the sluggish kinetics of this solid–liquid transition reaction. Hence, the presence of interfacial H₂O molecules with stable hydrogen-bond networks is crucial for fast proton transport and, consequently, high interfacial reaction activity. Overactive H₂O molecules construct short-lived hydrogen bond networks, which support only fast but discontinuous proton hopping, while a rigid H₂O molecule configuration cannot provide a rational proton transfer path. Hence, this work proposes the use of synergy between the cationic solvation effect and solid–liquid electrolyte to constrain the in situ dissolved cations at the cathode interface to construct moderate and connective hydrogen bond networks of solvated H₂O molecules. The resulting K/Cu/MnO₂ cathode with a ZnMT-based electrolyte provided the highest specific capacity of 360 mAh g⁻¹ at 0.4 mA cm⁻², and retained a high specific capacity of 450 mAh g⁻¹ after rate performance testing. These findings pioneer new avenues in interface engineering, providing theoretical foundations for the rational design of AZMBs with rapid kinetic responses.