Construction of CoF ₂ nanoconfined in N‐doped carbon matrix as high‐capacity cathodes to boost reversibility of lithium‐ion batteries

Abstract Metal fluoride materials with high theoretical capacities are considered the next generation of Li‐free conversion cathodes. However, the inherently sluggish reaction kinetics of metal fluorides result in unsatisfactory electrochemical performance. In this study, CoF 2 was combined with carbonaceous materials to obtain graphitic carbon‐encapsulated CoF 2 nanoparticles uniformly embedded in an interconnected N‐doped carbon matrix (CoF 2 @NC), significantly boosting the inert kinetics and electronic conductivity. The CoF 2 @NC nanocomposites exhibited a notable reversible capacity of 352.0 mAh·g −1 at 0.2 A·g −1 . Notably, it maintained superior long‐term cycling stability even at a high current density of 2 A·g −1 , with a capacity of 235.5 mAh·g −1 after 1200 cycles, evidently exceeding that of commercially available CoF 2 electrodes. Kinetic analysis indicated that the enhanced electrochemical performance originated from the increased contribution of capacitive effects. Furthermore, in‐situ electrochemical impedance spectroscopy (EIS) results verify that the improved cycling performance is associated with the enhanced interfacial stability of CoF 2 @NC. This research not only proposes a solution for the challenges of conversion cathodes in lithium‐ion batteries, but also offers novel synthesis strategies for designing high‐energy metal fluoride materials.