S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Chemical and Biological Engineering (화학생물공학부) Journal Papers (저널논문_화학생물공학부)
Solid-State NMR and Electrochemical Dilatometry Study on Li+ Uptake/Extraction Mechanism in SiO Electrode
- Kim, Taeahn; Park, Sangjin; Oh, Seung M.
- Issue Date
- Electrochemical Society
- J.Electrochem. Soc., 154, A1112 (2007)
- This work reports the Li+ uptake/extraction mechanism in silicon monoxide (SiO) as the negative electrode in lithium secondary
batteries. A combined study of solid-state 29Si- and 7Li-nuclear magnetic resonance (NMR), electrochemical dilatometry, and
charge-discharge cycling consistently demonstrates that the SiO2 domain in SiO irreversibly reacts with Li+ to produce lithium
silicates and Li2O in the first discharging period, whereas the elemental Si domain reversibly reacts, delivering the same chargedischarge
characteristics to those of conventional amorphous Si electrodes. The volume expansion accompanied by the irreversible
reaction is less significant than that caused by the lithiation of Si domain. The postmortem analysis made on cycled electrodes
reveals a phase segregation between the lithium silicates/Li2O and lithiated Si phase. It is likely that the lithium silicates/Li2O
phase plays a buffering role against the volume change of Si matrix, but the crack formation at the phase boundaries and eventual
pulverization are still a problem to be solved.
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