Decoupling electrolytes towards stable and high-energy rechargeable aqueous zinc-manganese dioxide batteries

Aqueous battery systems feature high safety, but they usually suffer from low voltage and low energy density, restricting their applications in large-scale storage. Here, we propose an electrolyte-decoupling strategy to maximize the full potential of Zn-MnO2 batteries by simultaneously enabling the optimal redox chemistry of both the Zn and MnO2 electrodes. The decoupled Zn-MnO2 battery exhibits an open-circuit voltage of 2.83 V (in contrast to the typical voltage of 1.5 V in conventional Zn-MnO2 batteries), as well as cyclability with only 2% capacity fading after deep cycling for 200 h. Benefiting from the full utilization of MnO2, the Zn-MnO2 battery is also able to maintain approximately 100% of its capacity at various discharge current densities. We also demonstrate the feasibility of integrating the Zn-MnO2 battery with a wind and photovoltaic hybrid power generating system. This electrolyte-decoupling strategy is shown to be applicable for other high-performance zinc-based aqueous batteries such as Zn-Cu and Zn-Ag batteries. Low energy density and limited cyclability are preventing the commercialization of aqueous Zn-MnO2 batteries. Here, the authors combine the merits of operating Zn anodes in alkaline conditions and MnO2 cathodes in acidic conditions, via an electrolyte-decoupling strategy, to realize high-performance batteries.