Realization of Long‐Life Proton Battery by Layer Intercalatable Electrolyte

Abstract Proton batteries have attracted increasing interests because of their potential for grid‐scale energy storage with high safety and great low‐temperature performances. However, their development is significantly retarded by electrolyte design due to free water corrosion. Herein, we report a layer intercalatable electrolyte (LIE) by introducing trimethyl phosphate (TMP) into traditional acidic electrolyte. Different from conventional role in batteries, the presence of TMP intriguingly achieves co‐intercalation of solvent molecules into the interlayer of anode materials, enabling a new working mechanism for proton reactions. The electrode corrosion was also strongly retarded with expanded electrochemical stability window. The half‐cell therefore showed an outstanding long‐term cycling stability with 91.0 % capacity retention at 5 A g −1 after 5000 cycles. Furthermore, the assembled full batteries can even deliver an ultra‐long lifetime with a capacity retention of 74.9 % for 2 months running at −20 °C. This work provides new opportunities for electrolyte design of aqueous batteries.