A strategy and detailed explanations to the composites of Si/MWCNTs for lithium storage

Nano-Si/MWCNTs composite was a representative solution to improve Si-based anode material's rate performance in lithium-ion batteries (LIBs). However, the problems of easy agglomeration of silicon nanoparticles and carbon nanotubes hindered Si/MWCNT's further development. In this study, we combine silicon nanoparticles with MWCNTs cleverly by utilizing freeze-drying method to solve the problems and enhance silicon-based material's rate performance. Compared with Si-MWCNTs composite treated by electric blast-drying method, the rate performance of Si-MWCNTs treated by freeze-drying is significantly improved, especially at different current densities. When Si-MWCNTs are encapsulated in FPC (flour-derived porous carbon, FPC), the as-obtained Si-MWCNTs-PVPC-FPC-SC-1 (sucrose-derived carbon, SC) prepared by freeze-drying method delivers a reversible capacity of 1347.5 mAh g(-1) at 0.1 A g(-1) after cycling at 5 A g(-1) and a reversible capacity of 501 mAh g(-1) at 1 A g(-1) after 500 cycles. Our study demonstrates that the freeze-drying method can solve the problems of easy agglomeration of silicon nanoparticles and MWCNTs as well as improve Si-based anode's rate performance for LIBs. The synthetic route presented in this paper is low-cost and easy to scale up for silicon-carbon (Si/C) composites with high rate performance and long cycle life. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study successfully addressed the issues of easy agglomeration of silicon nanoparticles and MWCNTs by cleverly combining them using the freeze-drying method to enhance the rate performance of silicon-based materials. The freeze-dried Si-MWCNTs composite demonstrated significantly improved rate performance at different current densities compared to other drying methods.