Enhanced Conductivity, Electrochemical Performance, and Chemical Stability of Lithium-Ion Batteries Based on Electrospun Polyacrylonitrile Hybrid Membrane

Abstract Replacing liquid electrolytes with solid ones is regarded as an essential strategy to mitigate safety concerns in lithium-ion batteries. However, the lower ionic conductivity of solid polymer electrolytes (SPEs) compared to conventional liquid electrolytes still hinders their practical application. In this work, we propose a composite polymer electrolyte (CPE) by incorporating a poly(ethylene oxide) (PEO) matrix with high-content lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into an electrospun polyacrylonitrile (PAN)-based three-dimensional nanofiber framework. Active fillers of LLZTO nanoparticles and LiClO4 were further introduced into the PAN skeleton to construct additional ion-conducting pathways (designated as PLLP). This design of coembedding dual active fillers inside the electrospun nanofibers, rather than simply dispersing them in the PEO matrix, is distinct from conventional CPEs and provides continuous and fast-ion channels. The morphology and diameter distribution of electrospun fibers were optimized by varying PAN concentration. Consequently, the optimized PLLP composite electrolyte achieves a superior ionic conductivity of 1.12 × 10–4 S cm–1 at 30 °C, an electrochemical stability window up to 4.75 V, and a lithium-ion transference number of 0.53, which is substantially higher than those of conventional PEO-based electrolytes. Moreover, the LiFePO4/PLLP/Li solid-state battery delivers a high specific discharge capacity of 161 mAh g–1 at 60 °C at 0.5C after 95 cycles with a capacity retention of 96%, as well as excellent rate capability. These results demonstrate that the synergistic coupling of active fillers and a 3D electrospun framework provides an effective strategy for simultaneously enhancing ionic conductivity, electrochemical stability, and cycling performance in all-solid-state lithium batteries.