The Self‐Expanding Frame of Graphydiyne Induces Rapid Transport of Lithium Ions in All‐Solid‐State Lithium Metal Batteries

Abstract Low ionic conductivity hinders the practical application of solid polymer electrolytes. Here, an interface‐oscillating polymer electrolyte (IOPE) based on graphdiyne (GDY) is designed and prepared to enable high‐performance all‐solid‐state lithium (Li) metal batteries (ASSLMBs). The affinity of GDY to Li ions induces the competitive adsorption of Li ions, weakens the coordination ability of Li ions with electron‐rich oxygen (on ethylene oxide), and accelerates the Li‐ion migration kinetics. The weak coordination between Li⁺‐acetylene greatly promotes the rapid reversible transition of GDY itself, resulting in strong self‐expanding/shrinking of the GDY skeleton and the GDY/polymer interface oscillation, and the reduction of the Li‐ion diffusion energy barrier at the interfaces. Consequently, the as‐prepared IOPE shows significantly improved Li‐ion conductivity (1.5 × 10⁻⁴ S cm⁻¹ at 35 °C) and transference number, as well as excellent stability toward Li metal anodes. The ASSLMBs assembled with LiFePO₄ cathodes and IOPE exhibit excellent rate and cycling performance, capable of stable operation for more than 250 cycles with a high‐capacity retention of 98% at 0.1C (1C = 170 mA g⁻¹). The high‐performance all‐solid‐state Li metal pouch cells are also demonstrated to show great potential for the practical application of IOPE.