Controlling Intermolecular Interaction and Interphase Chemistry Enabled Sustainable Water-tolerance LiMn₂O₄||Li₄Ti₅O₁₂ Batteries

Solid electrolyte interphase (SEI) formation and H₂O activity reduction in Water-in-Salt electrolytes (WiSE) with an enlarged stability window of 3.0 V have provided the feasibility of the high-energy-density aqueous Li-ion batteries. Here, we extend the cathodic potential of WiSE by rationally controlling intermolecular interaction and interphase chemistry with the introduction of trimethyl phosphate (TMP) into WiSE. The TMP not merely limits the H₂O activity via the strong interaction between TMP and H₂O but also contributes to the formation of reinforced SEI involving phosphate and LiF by manipulating the Li⁺ solvation structure. Thus, water-tolerance LiMn₂O₄ (LMO)||Li₄Ti₅O₁₂ (LTO) full cell with a P/N ratio of 1.14 can be assembled and achieve a long cycling life of 1000 times with high coulombic efficiency of >99.9 %. This work provides a promising insight into the cost-effective practical manufacture of LMO||LTO cells without rigorous moisture-free requirements. © 2022 Wiley-VCH GmbH.