Thermal pyrolysis of Si@ZIF-67 into Si@N-doped CNTs towards highly stable lithium storage

作者：Jin, Dun; Yang, Xianfeng; Ou, Yuqing; Rao, Mumin; Zhong, Yaotang; Zhou, Guangmin; Ye, Daiqi; Qiu, Yongcai^*; Wu, Yuping; Li, Weishan^*

来源：Science Bulletin, 2020, 65(6): 452-459.

DOI：10.1016/j.scib.2019.12.005

• N-doped CNTs
• In situ growth
• Silicon nanoparticles
• Lithium storage
• Cyclic stability

Silicon is attracting considerable attention as an active anode material for advanced lithium-ion batteries due to its ultrahigh theoretical capacity. However, the reversible utilization of silicon-based anode materials is still hindered by the rapid capacity decay, as a consequence of the huge volume change of silicon during cycling. Herein, we use a Co-zeolitic imidazole framework (ZIF-67) to prepare silicon-wrapped nitrogen-doped carbon nanotubes (Si@N-doped CNTs) by controllable thermal pyrolysis. The as-prepared nanocomposites can effectively prevent pulverization and accommodate volume fluctuations of silicon during cycling. It can deliver a highly reversible capacity of 1100 mAh g(-1) even after 750 cycles at a current density of 1000 mA g(-1). As confirmed by an in situ transmission electron microscopy experiment, the remarkable electrochemical performance of Si@N-doped CNTs is attributed to the high electronic conductivity and flexibility of cross-linked N-doped CNTs network as a cushion to mitigate the mechanical stress and volume expansion. Furthermore, a full cell consisting of Si@N-doped CNTs anode and LiFePO4 cathode delivers a high reversible capacity of 1264 mAh g(-1) and exhibits good cycling stability (>85% capacity retention) over 140 cycles at 1/4 C (1 C = 4000 mA g(-1)) rate.