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

Abstract 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|LiFePO 4 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.