Al-doped garnet nanofiber-reinforced cathode-supported composite solid electrolyte membranes for advanced all solid-state lithium batteries

Solid-state electrolytes (SSEs), which offer enhanced safety and performance in energy storage applications, are emerging as a viable substitute for traditional liquid electrolytes. However, the current generation of polymer solid electrolytes (PSEs) is constrained by their pronounced interfacial resistance with electrodes and intrinsically low ionic conductivity. Here, we introduce a novel cathode-supported composite solid electrolyte (CSE) membrane based on Polyethylene oxide (PEO) and garnet ceramic nanofibers (Al-doped Li 7 La 3 Zr 2 O 12 , LLZAO). The ceramic nanofibers, synthesized via electrospinning and single-step sintering, are homogeneously dispersed within a PEO matrix and deposited onto the cathode via a tape-casting method. This integrated design enhances continuous Li + transport and improves the electrolyte-cathode interfacial contact, yielding substantial gains in electrochemical stability and ionic conductivity. The optimized CSE membrane, with 15 wt% ceramic nanofibers, exhibits a 5.6 V stability window and an ionic conductivity of 6.19 × 10 −4  S cm −1 at 60 °C. The resulting all-solid-state LFP//Li battery, featuring the cathode-supported CSE membrane, delivers a specific capacity of 143 mAh g −1 following 115 cycles at 0.5C, maintaining a remarkable capacity retention rate of 94.1 % and a 99 % average coulombic efficiency. This study presents a scalable approach for enhancing the performance of solid-state electrolyte membranes, signifying a critical advancement in all-solid-state lithium-ion batteries (ASSLIBs) and energy storage technologies.