Self-Healing Interfacial Cross-Links Enable Supertough Solid Polymer Electrolytes with Eliminating-Dendrite Lithium Metal Battery

The integration of solid-state inorganic fillers into polymer matrices can improve the performance of solid lithium metal batteries. However, there is poor interface interaction between the polymer matrix and solid-state inorganic fillers, which has led to the performance of solid lithium metal batteries falling far short of expectations. Here, we constructed a bridging interaction based on borate ester dynamic cross-linking to prepare a supertough and self-healing poly(vinylidene fluoride)-hexafluoropropylene/graphene oxide/borate bonds/Li6.5La3Zr1.5Ta0.5O12 solid polymer electrolyte. The electrolyte exhibits a wide electrochemical window (4.84 V), high elongation at break (205%), outstanding thermal stability (200 °C), and high-capacity retention (90.3% after 900 cycles under 2C). We further revealed the influence of borate ester dynamic cross-linking on the performance of solid polymer electrolyte through density functional theory calculations. This work offers insight into designing high-performance solid polymer electrolytes for solid-state batteries.