Multi-buffer engineering of nitrogen-doped carbon nanosheets/carbon nanotubes network encapsulated and carbon coated silicon anode for high performance lithium-ion batteries

Abstract

The commercial application of silicon (Si) anode is still hindered by unfavorable phenomena such as huge volume expansion, low intrinsic conductivity and unstable solid electrolyte interface film of Si during cycling. Developing a simple and scalable synthesis for multi-buffer engineering with different carbon structures is significant and challenging for the commercial prospects of Si anode. Herein, we propose a multi-buffer engineering strategy with nitrogen-doped carbon nanosheets/carbon nanotubes network encapsulated and carbon-coated Si hybrid structure (Si@C@N-CNs/CNTs) via an efficient and convenient resin coating followed by in-situ catalytic pyrolysis of melamine and paraffin oil. The designed Si@C@N-CNs/CNTs delivers high discharge capacity (2950.6 mAh g−1 at 0.4 A g−1), good cyclability (1017.4 mAh g−1 after 350 cycles), and outstanding rate performance (1068.5 mAh g−1 at 8 A g−1). The electrochemical kinetics and structural stability test results demonstrate such superior performance is originated from the multi-buffer engineering by the 3D conductive N-CNs/CNTs networks, carbon coated layer and fine dispersed CoSi2 nanoparticles, which can provide fast electron and ion transfer, effective volume buffer effect and excellent structural stability. Direct comparison with other two Si anodes reveals the significance of the multi-buffering synergistic effect and its great potential in application of high-performance anode for lithium-ion batteries.