Flexible and Interfacial Stable Composite Polymer Electrolyte Membrane for Solid‐State Lithium‐Oxygen Battery: Dispersion of Anti‐perovskite in Insulating Polyethylene Oxide

This study pioneers the first-ever integration of an advanced composite polymer electrolyte (CPE) based on polyethylene oxide (PEO) and anti-perovskite into solid-state lithium-oxygen batteries, highlighting its potential in revolutionizing battery performance. The anti-perovskite Li₂OHCl (LOC) exhibits exceptional ionic conductivity of 1.8 × 10^-3 S cm^-1. When combined with PEO, the CPE achieves ionic conductivities of 0.56 × 10^-3 S cm^-1 at 25 °C and 1.92 × 10^-3 S cm^-1 at 60 °C, seven times higher than conventional PEO membranes. With a lithium-ion transference number of 0.698, this CPE stands among the best solid electrolytes reported. Compared to liquid electrolytes, lithium symmetric cell with CPE shows a voltage drop of 50% and stable cycling for over 1000 h, demonstrating excellent compatibility with lithium. Additionally, an in situ hybrid polymer electrolyte (HPE) at cathode forms a 3D electronic and ionic conducting network, expanding triple-phase boundary. Therefore, solid-state lithium-oxygen batteries based on HPE/carbon nanotubes || CPE || Li achieve a discharge capacity of 9.5 mAh cm^-2 and with 1000 h cycle life, nearly 50 times longer than original PEO membranes. This work establishes a new benchmark for lithium-oxygen batteries, underscoring the transformative potential of anti-perovskite CPEs in next-generation energy storage technologies.