Synergistic Regulation of Li─O Binding and Anion Anchoring by Lewis Acidic Perovskites for Ultra-Stable PEO-Based...

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes are promising candidates for all‑solid‑state lithium metal batteries, yet they are hampered by excessive Li⁺-coordination that inherently restricts ionic conductivity and electrochemical stability. Herein, defect-rich layered perovskite Pr_{2- x}Sr_xNiO₄ nanofillers are introduced via a Sr-doping strategy to decouple these limitations. Mechanistically, the engineered oxygen vacancies and Ni³⁺ Lewis acid sites function as dual regulators that anchor TFSI^- anions to foster a stable inorganic-rich SEI, while concurrently weakening the Li-O binding to expedite Li⁺ transport kinetics. Consequently, the optimized electrolyte achieves a superior ionic conductivity of 5.17  ×  10^-4 S cm^-1 at 60 °C, an elevated Li⁺ transference number of 0.56 at 25°C, and a broadened electrochemical stability window extending up to 4.9 V. Benefiting from these enhancements, the Li||Li symmetric cell demonstrates ultra-stable cycling for over 4000 h (0.1 mA cm^-2). In full cells, the electrolyte enables the LiFePO₄ cathode to deliver an initial discharge specific capacity of 151.6 mAh g^-1 with robust retention over 500 cycles at 1 C, while also ensuring superior rate and cycling performance with the high-voltage Ni_0.8Co_0.1Mn_0.1O₂ cathode. Ultimately, this study validates defect engineering as a potent strategy to unlock high-performance PEO-based all-solid-state batteries.