Realizing Ultrathin and Highly Conductive Polymer Electrolytes by Coupling Rigid‐Rod Polyelectrolytes with High‐Speed Electrospinning

Abstract Developing solid‐state polymer electrolytes (SPEs) for lithium metal batteries (LMBs) necessitates a meticulous balancing of ionic conductivity, mechanical strength and thickness. Conventional methods often prioritize one property at the expense of others. This study introduces a unique strategy by integrating the rigid‐rod polyelectrolyte poly 2,2′‐disulfonyl‐4,4′‐benzidine terephthalamide (PBDT) with high‐speed roller‐assisted electrospinning to form an aligned nanofiber network without additional mechanical frameworks. This design results in ultra‐thin SPEs (<10 µm) with high modulus (1.28 GPa), meanwhile offering remarkable ionic conductivity (3.08 mS cm −1 at 30 °C) and high interfacial compatibility (2.33 Ω cm 2 ) with lithium metal anodes. The X‐ray scattering results reveal the multi‐scale alignments in PBDT chains with the accelerated Li⁺ transport pathways. This pathway achieves a uniform Li⁺ flux and can effectively suppress dendrite growth. Notably, the Li||Li cell demonstrates superior stability for nearly 4000 h at a current density of 0.5 mA cm −2 . High‐mass‐loading LiFePO 4 (LFP)||Li full cells display exceptional long‐term cycling stability, retaining 90% of their capacity after 380 cycles at a 0.5 C rate. This approach effectively addresses the trade‐offs among SPE thickness, ionic conductivity and mechanical performance, providing valuable insights for the development of flexible and high‐performance lithium metal batteries.