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Encapsulation and networking of silicon nanoparticles using amorphous carbon and graphite for high performance Li-ion batteries

Parekh, Mihit H., Parikh, Vihang P., Kim, Patrick J., Misra, Shikhar, Qi, Zhimin, Wang, Haiyan, Pol, Vilas G.
Carbon 2019 v.148 pp. 36-43
anodes, electrical conductivity, electrochemistry, electrolytes, encapsulation, graphene, lithium batteries, nanoparticles, silicon, wheat flour
Considering the limited theoretical capacity of graphite (372 mAh g−1), graphite-Si (G-Si) composites have shown promise as high capacity anode for lithium-ion batteries during last few years. However, electrochemical reactions associated with a significant volume change of Si during repetitive cycles cause fatal technical issues (e.g. particle fragmentation, excessive solid electrolyte interface formation, electrode pulverization, etc.) and thus impede the practical use of Si electrodes. In this study, we used a commercially available wheat flour as a carbon source to improve the electrical conductivity and effectively accommodate the volume expansion of the G-Si electrode. The designed graphite-silicon-wheat carbon (GSiWh) composite architecture comprising 25 wt% Si nanoparticles delivered a high initial capacity of 804 mAh g−1 with an initial coulombic efficiency of 74% and retained 595 mAh g−1 specific capacity after 200 cycles. The high performance and stability are attributed to the enhanced structural stability and improved electrochemical kinetics enabled by full coverage of the amorphous carbon. The proposed strategy of introducing an amorphous carbon into G-Si composites minimizes the intrinsic issues of Si electrode providing alternative solution to advance the development of Si-based anode electrode.