Nanoneedles of Cobalt Hydroxyfluoride on N-Doped Porous Carbon as Anodes for Lithium-Ion Batteries

The development of new composite materials with micro- and nanostructures and the realization of rapid transmission of lithium ions are crucial for the high-performance anode materials of lithium-ion batteries. Cobalt-based composites have received considerable attention on account of their unique physicochemical properties and good electrochemical performance. Therefore, it is of great significance to synthesize new Co-based composites and to research their electrochemical properties. In this work, nanoneedle CoOHF was successfully loaded on N-doped porous carbon (CoOHF/N–C) by facile sintering and hydrothermal method for the first time, which possessed excellent cycle stability and fast lithium-ion transport kinetics. The special porous structure in CoOHF/N–C can effectively alleviate the volume effect of CoOHF during cyclic charging and discharging, and the nanoneedle CoOHF presents a flower-like structure, which can also provide a large specific surface area, which ensures more active sites and shorter diffusion paths for rapid Li+ diffusion, thus offering a larger electrode/electrolyte interface for charge transfer. Under these synergistic effects, the CoOHF/N–C anode has excellent electrochemical performance, including an admirable initial discharge capacity of 1203.7 mAh g–1 at 200 mA g–1, a high reversible capacity of 913.3 mAh g–1 after 300 cycles, and a high Li+ diffusion coefficient, ensuring improved cycling stability and rate performance. This work opens up the possibility of novel ways of designing new Co-based nanoanode materials for high-performance lithium-ion batteries.