Study of lithiation mechanisms of high performance carbon-coated Si anodes by in-situ microscopy

Zheng Long Xu, Ke Cao, Sara Abouali, Mohammad Akbari Garakani, Jiaqiang Huang, Jian Qiu Huang, Elham Kamali Heidari, Hongtao Wang (Corresponding Author), Jang Kyo Kim (Corresponding Author)

Research output: Journal article publicationJournal articleAcademic researchpeer-review

40 Citations (Scopus)

Abstract

Carbon coated Si (Si/C) composites with a high Si content of 81 wt% are synthesized by one-pot carbonization of the mixture containing commercial Si particles and polyvinylidene fluoride (PVDF) at an optimized temperature. The Si/C electrodes deliver a high cyclic capacity of 2003 mA h g-1 at 0.5 A g-1 after 50 cycles and an enhanced rate capability of ~750 mA h g-1 at 4 A g-1 for over 200 cycles. The effect of ultrathin carbon coating on lithiation mechanisms of Si particles is evaluated using the in-situ transmission electron microscopy (TEM). It is revealed that the carbon-coated Si particles undergo an isotropic to anisotropic transition during the initial lithiation, whereas such transition is not observed for the uncoated Si particle. The lithiation rate of Si/C is 3-4.5 times faster than that of uncoated Si with the same diameter, a testament to high rate capacities of Si/C in real batteries. The flexible, amorphous carbon coating favorably alters the damage mode of Si particles from pulverization by multiple cracking to fracture by a single crack. The above findings offer fundamental understanding and practical guideline for designing carbon coatings of Si-based electrodes with much enhanced electrochemical performance.

Original languageEnglish
Pages (from-to)45-54
Number of pages10
JournalEnergy Storage Materials
Volume3
DOIs
Publication statusPublished - 1 Apr 2016
Externally publishedYes

Keywords

  • Carbon coating
  • in-situ TEM
  • Li-ion batteries
  • Silicon particles

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Energy Engineering and Power Technology

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