Highly improved aqueous ZnLiMn₂O₄ hybrid-ion batteries using poly(ethylene glycol) and manganese sulfate as electrolyte additives

Aqueous Zn metal batteries are a promising candidate for low-cost, safe, and sustainable energy storage systems. Nonetheless, the practical application of such batteries is still impeded by the inferior Zn anode performance and instability of the cathode. Herein, we investigate the performance of an aqueous Zn & Vert;LiMn2O4 (Zn & Vert;LMO) hybrid battery with a bi-salt (ZnSO4 and Li2SO4) electrolyte modified with a low dosage of poly(ethylene glycol) (PEG200) and MnSO4. The PEG additive effectively inhibits water decomposition, mitigates Zn metal corrosion, and promotes the in-plane growth of hexagonal Zn flakes. As a result, the reversibility of Zn plating/stripping and the long-term cyclability of the Zn & Vert;LMO hybrid battery can be substantially enhanced in the modified electrolyte. Specifically, in our optimized electrolyte ZL-8% PEG-0.1 Mn, the Zn & Vert;LMO hybrid battery exhibits an initial capacity of 91.2 mA h g(-1) and a capacity retention of 50% in 500 cycles at 2C, along with improved coulombic efficiency and self-discharge behavior. This dual-additive strategy can be used to design low-cost, highly reversible, safe, and long-cycling Zn-Li hybrid-ion batteries for practical applications.