Quasi‐Decoupled Solid–Liquid Hybrid Electrolyte for Highly Reversible Interfacial Reaction in Aqueous Zinc–Manganese Battery

Aqueous zinc-manganese batteries with low cost, reliable safety, and considerable energy density, show promise for grid-scale storage. Their durable operation is highly dependent on the reversibility and stability of both electrode interfaces, which is limited by the different requirements of the interfaces of manganese-based cathodes and zinc anodes. Here, a quasi-decoupled solid-liquid hybrid electrolyte is proposed, which demonstrates good compatibility and high reversibility for both interfaces with different electrolyte environments, showing quasi-decoupling characteristics. Such a hybrid electrolyte can endow the anode interface with abundant favorable nucleation sites for achieving uniform zinc platting/stripping, as well as limit the presence of free H2O molecules, to suppress side-reactions. This electrolyte is also adapted to a reversible and stable MnO2/Mn2+ manganese deposition/dissolution reaction at the cathode interface by restricting OH-/H+ ion diffusion, preventing formation of irreversible electrochemically inert MnOOH. As a result, the quasi-decoupled solid-liquid hybrid electrolyte enables Zn||Zn cycling for more than 500 h, and a specific capacity of a Zn||alpha-MnO2 battery up to 348 mAh g(-1) at 0.2 A g(-1). It also allows 87% capacity retention after 500 cycles at 0.5 A g(-1). This work provides a new insight into electrolyte design that focuses on the different requirements of differing electrode interfaces.