Synergistic Composite Solid Electrolyte Based on Multifunctional Polymer Networks for High‐Performance Lithium Metal Batteries

The advancement of polymer-based solid-state electrolytes (SPEs) is essential for the development of high energy density (ED) and long-operation durability lithium-metal batteries (LMBs). However, conventional poly (ethylene oxide) (PEO)-based electrolytes suffer from insufficient ionic conductivity (IC) at room temperature (RT) and limited capability to suppress lithium (Li) dendrite growth, particularly under high-rate operations. These challenges arise from unfavorable anion-solvate structures, which lead to a reduced Li-ion transference number (LITN) and hinder efficient ion transport. Here, a facile and scalable strategy is presented to design a self-healing composite polymer electrolyte by incorporating iminoboronate-functionalized networks. By succinonitrile (SN) into an anion-trapping polymer matrix, this approach enhances LITN while preserving overall IC. The resulting electrolyte facilitates rapid, selective, and uniform Li-ion transport, enabling stable LMB operation at 1 C for 480 cycles with an impressive 88% capacity retention. Moreover, the exceptional self-healing capacity of the iminoboronate-based polymer electrolyte (I-SHPE) significantly reinforces the mechanical properties of PEO-based electrolytes. The SN-embedded I-SHPE (I-SN-SHPE) exhibits a synergistic combination of high IC, anion-capture ability, and rapid self-healing properties. This work provides a promising strategy to overcome the intrinsic limitations of conventional PEO-based electrolytes, paving the way for safer and more durable LMBs.