Self‐Healing Hydrogel Electrolyte Enabled by Dynamic Polar Covalent and Noncovalent Interactions for High‐Performance Rechargeable Zinc‐Metal Batteries: A Leap toward Sustainable Energy Storage

Abstract Hydrogel polymer electrolytes with superior multifunctional properties are promising alternatives to aqueous electrolytes for resolving interfacial issues in rechargeable zinc‐metal batteries. In this study, an intrinsic self‐healing hydrogel polymer electrolyte (PHBC‐4) is synthesized, engineered through an integrated approach involving the polar covalent (B─O bond), hydrogen‐bond (polyvinyl alcohol‐hydroxypropyl methylcellulose interface), and coordination‐type (Zn─O) interactions to enable self‐healing functionality. The PHBC‐4 has demonstrated high ionic conductivity (4.6 × 10 −2 S cm −1 ), good oxidative stability (2.3 V vs Zn|Zn 2+ ), a high cation transference number (0.89), superior tensile strength (0.32 MPa), and an impressive healing efficiency of 93% achieved just within 5 min, confirming its robust self‐healing capability. In Zn||Zn symmetric cells, it effectively suppresses dendrite growth, ensuring stable cycling for over 1032 h with an areal capacity of 1.0 mAh cm −2 at a current density of 1.0 mA cm −2 . When paired with a Zn‐doped MnO cathode in the rechargeable homemade pouch cell, the system delivers a high specific capacity of 160 mAh g −1 at 0.10 A g −1 and cycling stability up to 493 charge–discharge cycles at 2.0 A g −1 . The self‐healing ability of PHBC‐4 HGPE is confirmed in a homemade pouch cell via OCV and charge–discharge tests, demonstrating stable performance. The DFT studies confirm molecular‐level interactions within the hydrogel heterostructure.