Gel Electrolyte Self-Healing via Dynamic Reversible Bonds for Stable Lithium Plating/Stripping in Lithium Metal Batteries

Solid polymer electrolytes in lithium metal batteries (LMBs) are susceptible to mechanical damage from lithium dendrite puncture and deformation. Although integrating self-healing functionality helps to alleviate this issue, it typically compromises either mechanical strength or ionic conductivity. To overcome this trade-off, self-healing electrolytes (AU x –BMIM y IGEs) were developed through the synergistic combination of ureido pyrimidinone (UPy)-based polymers and an imidazolium ionic liquid. The designed supramolecular networks feature quadruple hydrogen bonds from UPy units and ion–dipole interactions between imidazolium cations and polymer carbonyl groups. The mechanical strength of the electrolyte is enhanced by these dynamic reversible bonds, while the exceptional self-healing efficiency is enabled by their capacity for rapid reorganization. The ionic liquid further enhances the ionic conductivity. The optimized IGEs, named as AU 7 –BMIM 15 IGEs, balance the tensile stress of 1.26 MPa, the ionic conductivity of 3.40 × 10 –4 S cm –1, and ultrahigh self-healing efficiencies. After being cut and healed at 45 °C for merely 1 h, the Healed-AU 7 –BMIM 15 IGEs achieved healing efficiencies of 97.6% in tensile strength and 99.1% in ionic conductivity. This efficient healing capability contributes to the remarkable stability of lithium plating/stripping. The Li||Li symmetric cell assembled with Healed-AU 7 –BMIM 15 IGEs stably cycled for over 4500 h at 0.1 mA cm –2 . Furthermore, a Li||LiFePO 4 cell using Healed-AU 7 –BMIM 15 IGEs delivered cycling for 2000 h at 0.2 C with an average Coulombic efficiency exceeding 99%, performing comparably to fresh AU 7 –BMIM 15 IGEs. The practical viability was further underscored by multipoint puncture tests. The AU 7 –BMIM 15 IGE with 16 puncture sites retained a critical current density of 0.30 mA cm –2 after being healed at 45 °C for 1 h. This work demonstrates a promising strategy for creating self-healing electrolytes for next-generation LMBs.