期刊
NANOMATERIALS
卷 11, 期 1, 页码 -出版社
MDPI
DOI: 10.3390/nano11010018
关键词
Li-ion batteries; anodes; intermetallics; silicon; composites; nanomaterials; coating; mechanochemistry
类别
资金
- French Research Agency (ANR), project NEWMASTE [ANR-13-PRGE-0010]
- Agence Nationale de la Recherche (ANR) [ANR-13-PRGE-0010] Funding Source: Agence Nationale de la Recherche (ANR)
Coating silicon nanoparticles with carbon or oxide successfully reduces the chemical reaction between silicon and Ni3Sn4, enhancing the electrochemical performance of Si-Ni3Sn4 composite materials. Carbon-coated silicon exhibits better lithiation properties, delivering over 500 mAh/g for at least 400 cycles.
Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni3Sn4 composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi2, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni3Sn4 composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni3Sn4 during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni3Sn4-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles.
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