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

Abstract 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 H 2 O molecules, to suppress side‐reactions. This electrolyte is also adapted to a reversible and stable MnO 2 /Mn 2+ 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||α‐MnO 2 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.