A Safe Polyzwitterionic Hydrogel Electrolyte for Long‐Life Quasi‐Solid State Zinc Metal Batteries

Abstract Aqueous zinc metal batteries are safe, economic, and environmentally friendly. However, the dendrite growth and inevitable corrosion issues under aqueous condition greatly restrict the development of long cycling life zinc metal batteries. To achieve the long‐term reversible zinc deposition/dissolution, a polyzwitterionic hydrogel electrolyte (PZHE) is constructed with record high room temperature ionic conductivity of 32.0 mS cm −1 and Zn 2+ transference number of 0.656. The abundant hydrophilic and charged groups in the zwitterionic polymer can well immobilize water molecules in the polymer skeleton and reduce side reactions. The charged groups of the zwitterionic polymer can also homogenize the ion distribution and achieve uniform zinc deposition. Long cycling life of over 3500 h is achieved for the symmetric batteries with PZHE. Full cells with VS 2 and MnO 2 cathodes are also demonstrated to exhibit excellent cycling stability. With combined advantages of physical and chemical crosslinking gels, the PZHE enabled flexible quasi‐solid state zinc metal batteries with excellent processability, self‐healing property and safety, can operate even under various extreme conditions such as cutting, soaking, hammering, washing, burning, and freezing. It is believed that the PZHE can provide a promising opportunity and pave the way for other long‐life aqueous batteries.