Constructing Robust LiF‐Enriched Interfaces in High‐Voltage Solid‐State Lithium Batteries Utilizing Tailored Oriented Ceramic Fiber Electrolytes

Abstract The pursuit of high‐performance energy storage devices has fueled significant advancements in the all‐solid‐state lithium batteries (ASSLBs). One of the strategies to enhance the performance of ASSLBs, especially concerning high‐voltage cathodes, is optimizing the structure of composite polymer electrolytes (CPEs). This study fabricates a high‐oriented framework of Li 6.4 La 3 Zr 2 Al 0.2 O 12 (o‐LLZO) ceramic nanofibers, meticulously addressing challenges in both the Li metal anode and the high‐voltage LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode. The as‐constructed electrolyte features a highly efficient Li + transport and robust mechanical network, enhancing both electron and ion transport, ensuring uniform current density distribution, and stress distribution, and effectively suppressing Li dendrite growth. Remarkably, the Li symmetric cells exhibit outstanding long‐term lifespan of 9800 h at 0.1 mA cm −2 and operate effectively over 800 h even at 1.0 mA cm −2 under 30 °C. The CPEs design results from the formation of a gradient LiF‐riched SEI and CEI film at the Li/electrolyte/NCM811 dual interfaces, enhancing ion conduction and maintaining electrode integrity. The coin‐cells and pouch cells demonstrate prolonged cycling stability and superior capacity retention. This study sets a notable precedent in advancing high‐energy ASSLBs.