Hierarchically Aligned Aramid Nanofiber Aerogel Framework Enhances Ionic Transport and Interfacial Stability of Solid-State Lithium-Metal Batteries

Solid polymer electrolytes (SPEs) have attracted significant attention for enabling high-energy density and high-safety lithium metal batteries due to their low interfacial impedance, superior electrode compatibility, and mechanical flexibility. However, challenges such as low room-temperature ionic conductivity, limited Li⁺ transference number, and insufficient mechanical robustness still impede their practical applications. Herein, a novel SPE (denoted as PMVAL) is designed and supported by an aramid nanofiber (ANF) aerogel framework featuring vertically aligned ion transport channels. The ANF aerogel, fabricated via a non-solvent induced phase separation strategy, forms hierarchical multilayered pore arrays that promote directional Li⁺ migration within PMVAL, achieving an impressive high ionic conductivity of 0.82 × 10⁻⁴ S cm⁻¹ at 30 °C. This engineered framework also facilitates the formation of a functional organic-inorganic composite solid electrolyte interphase at the PMVAL/Li interface, enabling homogeneous lithium deposition and effective dendrite suppression. Consequently, Li|PMVAL|LiFePO₄ cells exhibit remarkable cycle stability, delivering over 5000 cycles at 1 C (60 °C) and 1000 cycles at 0.5 C (30 °C) with a Coulombic efficiency exceeding 99.8%. Moreover, flexible pouch cells demonstrate excellent safety and stability under mechanical abuse (bending, piercing, and cutting), indicating the great promise of this strategy for next-generation solid-state energy storage systems.