Lithiation of pure and methylated amorphous silicon: Monitoring by operando optical microscopy and ex situ atomic force microscopy

Yue Feng, Thuy Doan Trang Ngo, Marianthi Panagopoulou, Abdelhak Cheriet, Bon Min Koo, Catherine Henry-de-Villeneuve, Michel Rosso, François Ozanam

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Operando color microscopy and ex situ AFM were used to investigate the lithiation process in pure (a-Si:H) and methylated (a-Si 1-x (CH 3 ) x :H) amorphous silicon thin layers. Color analysis of optical images allows for monitoring thickness changes of a-Si:H layers. Unlike pure a-Si:H, the first lithiation of a-Si 1-x (CH 3 ) x :H is found to be spatially non-uniform: lithiation starts at a limited number of locations then expands radially, forming circular lithiation spots. The morphology of the lithiation spots and their evolution is accurately measured by ex situ AFM. A mechanism is proposed to explain this phenomenon, involving the high resistivity of methylated silicon and the existence of low-resistance point defects.

Original languageEnglish
Pages (from-to)249-258
Number of pages10
JournalElectrochimica Acta
Volume302
DOIs
StatePublished - Apr 10 2019
Externally publishedYes

Keywords

  • AFM
  • Amorphous silicon
  • Li-ion battery
  • Lithiation mechanism
  • Operando optical microscopy
  • Silicon anode

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