Lithiation kinetics of a Si-C composite anode for high-capacity lithium (Li)-ion batteries were investigated through in situ lithiation and electrochemical C-V measurements using a focused ion beam (FIB). Here, we found in the lithiation procedure that Li migrates sequentially into carbon (C), nanopores, and silicon (Si) in the Si-C composite. In the first lithiation step, Li was intercalated inside C particles while spreading over the surface of the C particles. The second lithiation process occurred through the filling of nanopores existing between electrode particles that consisted of the Si-C composite. The nanopores acted as a Li reservoir during the pore-filling process. Finally, the Si particles were lithiated with a volume expansion of ∼70%, corresponding to a 300% volume expansion of 25 wt % Si particles included in the composite anode. The nanopores did not accommodate a large volume expansion of Si particles, because pore-filling lithiation occurred before the Si lithiation in the charging process. We suggest a design rule related to the role of the nanopores of the Si-C composite anode in LIB systems.
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ASJC Scopus subject areas
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry