Graphite@silicon embedded in a carbon conformally coated tiny SiO2 nanoparticle matrix for high-performance lithium-ion batteries

Engineering of graphite@Si/carbon composites is considered as an effective strategy to surmount the shortcomings of the low conductivity and large volume expansion of bare Si anode materials for lithium-ion batteries. Nevertheless, their applications in high-performance electric vehicles are still c...

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Bibliographic Details
Published in:Inorganic chemistry frontiers 2021-10, Vol.8 (19), p.4395-4406
Main Authors: Liu, Huitian, Liu, Xu, Liu, Zhaolin, Tao, Junyan, Dai, Xiaoqian, Yang, Qi, Xu, Jikai, Shan, Zhongqiang
Format: Article
Language:English
Subjects:
Anodes
Carbon
Composite materials
Electric vehicles
Electrode materials
Graphite
Inorganic chemistry
Ion diffusion
Lithium
Lithium oxides
Lithium-ion batteries
Low conductivity
Nanoparticles
Rechargeable batteries
Sheaths
Silicon dioxide
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Summary:Engineering of graphite@Si/carbon composites is considered as an effective strategy to surmount the shortcomings of the low conductivity and large volume expansion of bare Si anode materials for lithium-ion batteries. Nevertheless, their applications in high-performance electric vehicles are still challenging owing to their limited accessible capacity. Herein, SiO2 as an active additive was introduced to improve the capacity of graphite@Si/carbon composites. Two different composites, graphite@Si sequentially embedded in SiO2 and carbon layers (G@Si/SiO2 layer/C) and encapsulated in a carbon conformally coated tiny SiO2 nanoparticle matrix (G@Si/SiO2 NPs/C), were well-designed. Both the Si/C composites exhibit a longer cycle life than the graphite@Si/C due to the unique double protective sheath of inert components (Li2O and Li4SiO4) and carbon. The former was formed during the first lithium insertion of SiO2. Specifically, the G@Si/SiO2 NPs/C shows a high specific capacity (607 mA h g−1), exceptional cycling stability (92% retention after 800 cycles at a 0.5 A g−1) and promising rate capability. The remarkable performances benefit from the porous three-dimensional network structure constructed by an amorphous carbon matrix shell and a graphite core, which well disperse and support Si and SiO2, thus improving their electrochemical activity, alleviating the volume change and increasing the Li-ion diffusion effectively.
ISSN:2052-1545
2052-1553
DOI:10.1039/d1qi00618e