ZIF-67-Derived\nN‑Doped Co/C Nanocubes as High-Performance Anode Materials for Lithium-Ion Batteries

Abstract

Co nanoparticles\nembedded in nitrogen-doped carbon nanocubes (Co/NCs) for applications\nas anode materials in rechargeable lithium-ion batteries were synthesized\nby calcining Co-based metal-organic framework. Sizes of Co nanoparticles\nwere ∼15 nm according to X-ray diffraction (XRD) and transmission\nelectron microscopy. Electrochemical performances of the as-prepared\nanode nanocube composite at 700 °C showed a high initial capacity\nof 1375.1 mAh g^–1 in the voltage range of 0.01–3.0\nV at the current rate of 0.1 A g^–1. After 100 cycles,\ncapacity remained at 688.6 mAh g^–1. Thereinto, the\nrole of Co nanoparticles in electrochemical reaction was also elucidated\nby in situ XRD experiment. Capacity increase of Co/NCs at the high\ncurrents was observed, which are potentially caused by the activation\nof electrode and pseudocapacitance during cycling. High surface area\nand abundant mesopores contributed to the improved electrochemical\nperformances of the anode, providing numerous pathways and sites for\nLi⁺ transfer and storage and accordingly contributing to\npseudocapacitance capacity.