Hetero‐Packing Nanostructures of Iron (III) Fluoride Nanocomposite Cathode for High‐Rate and Long‐Life Rechargeable Lithium‐Ion Batteries

Abstract High‐performance metal fluoride cathodes are crucial to design ultrahigh‐capacity lithium metal batteries for taking part in the next‐generation energy storage market. However, their insulating nature and sluggish reaction kinetics result in voltage hysteresis, low‐rate capability, and rapid capacity degradation. Herein, a generalizable one‐step melt synthesis approach is reported to construct hetero‐packing nanostructures of FeF 3 @C‐Asphalt nanocomposites, where ultrafine FeF 3 nanoparticles are homogeneously covered by a high conductive carbon framework. By the electrochemical kinetics calculation and multiphysics simulations, this FeF 3 @C‐Asphalt nanocomposites consist of ultrafine nanoparticles and a constrained carbon framework, offering a high tap density (1.8 g cm −3 ), significantly improved conductivity, and enhanced charge pathways, and thereby enabling the fast electron transport, rapid ion migration, depressed electrode internal stress, and mitigated volume expansion. As a result, the optimized FeF 3 @C‐Asphalt cathode delivers a high capacity of 517 mAh g −1 , high cyclic stability of 87.5% after 1000 cycles under 5 A g −1 (10 C), and excellent capacity retention of 77% from 0.5 A g −1 to 10 A g −1 (20 C, 250 mAh g −1 ). The work provides an easy‐to‐operate and low‐cost approach to accomplish high cyclic stability metal fluoride‐lithium batteries, which will guide the development of fast‐charging ultrahigh‐capacity cathode materials for the new energy industry.