Comprehensively Upgraded Lithium-Metal Batteries Achieved by the β/β″-Al2O3 Ceramic Solid Electrolyte

The conventional β/β″-Al₂O₃ ceramic-filled solid-state electrolytes (SSEs) can tailor ionic conductivity behaviors according to two ion-transport mechanisms by occupying cation vacancies and interstitial positions in the conductive plane. In this work, we present an electrospinning method to synthesize a three-dimensional (3D) cross-linked PAN nanofiber framework and multiphase Al₂O₃ ceramic (β) fillers that synergistically reinforced lithium-metal batteries and PEO-based solid-state electrolytes (denoted as PL–PB SSEs). Due to the continuous Li⁺-transport channels, enhanced mechanical strength, and superior interfacial compatibility, the resulting PL–PB SSEs exhibited uniform lithium deposition, high ionic conductivity (0.22 mS cm^–1), large Li⁺ transference number (0.66), and wide electrochemical stability window (5.07 V) at 45 °C. The assembled Li||Li symmetric cell with PL–PB SSE delivered excellent cycling stability at 0.1 mA cm^–2 and 0.1 mAh cm^–2 over 900 h with a lower hysteresis voltage overpotential of 16 mV. The all-solid-state Li||LFP full cell with PL–PB SSE showed a lower capacity decay of 0.003% per cycle after 450 cycles at 1.0C than that of PL–P SSE without β powders (0.04%). This strategy provides new insights for broadening the practical applications of multiphase Al₂O₃ ceramic coexistence in all-solid-state lithium-metal batteries.