Abstract
Abstract Rechargeable zinc aqueous batteries are key alternatives for replacing toxic, flammable, and expensive lithium‐ion batteries in grid energy storage systems. However, these systems possess critical weaknesses, including the short electrochemical stability window of water and intrinsic fast zinc dendrite growth. Hydrogel electrolytes provide a possible solution, especially cross‐linked zwitterionic polymers that possess strong water retention ability and high ionic conductivity. Herein, an in situ prepared fiberglass‐incorporated dual‐ion zwitterionic hydrogel electrolyte with an ionic conductivity of 24.32 mS cm−1, electrochemical stability window up to 2.56 V, and high thermal stability is presented. By incorporating this hydrogel electrolyte of zinc and lithium triflate salts, a zinc//LiMn0.6Fe0.4PO4 pouch cell delivers a reversible capacity of 130 mAh g−1 in the range of 1.0–2.2 V at 0.1C, and the test at 2C provides an initial capacity of 82.4 mAh g−1 with 71.8% capacity retention after 1000 cycles with a coulombic efficiency of 97%. Additionally, the pouch cell is fire resistant and remains safe after cutting and piercing.