High voltage hybrid Zn-MnO2/air batteries via decoupled electrolyte

Abstract

Although aqueous Zn-air batteries offer high energy density, safety, and low cost, achieving a sufficiently high output voltage remains a challenge. Here, we propose a novel dual-electrochemical synergistic coupling mechanism to construct a decoupled-electrolyte Zn-MnO₂/air hybrid battery, in which a single multifunctional C@Co-N-C electrode enables dynamic switching between the high-potential Mn²⁺/MnO₂ conversion reaction and the high-capacity oxygen reduction reaction (ORR). Nernst equation calculations indicate that under optimized conditions, the theoretical voltages of the Zn-MnO₂ and Zn-air reactions reach 2.787 V and 2.653 V, respectively. During discharge, the hybrid battery first delivers a high-voltage Zn-MnO₂ process at 2.63 V, followed by a high-capacity Zn-air process at 1.62 V. This sequential reaction mechanism achieves dual ultrahigh-voltage platforms in a single aqueous battery system for the first time, effectively overcoming the long-standing voltage limitation of conventional aqueous Zn-air batteries.