Raman Evidence for Late Stage Disproportionation in a Li-O2 Battery.

Abstract

Raman spectroscopy is used to characterize the composition of toroids formed in an aprotic Li-O2 cell based on an activated carbon cathode. The trends in the Raman data as a function of discharge current density and charging cutoff voltage provide evidence that the toroids are made up of outer LiO2-like and inner Li2O2 regions, consistent with a disproportionation reaction occurring in the solid phase. The LiO2-like component is found to be associated with a new Raman peak identified in the carbon stretching region at ∼1505 cm(-1), which appears only when the LiO2 peak at 1123 cm(-1) is present. The new peak is assigned to distortion of the graphitic ring stretching due to coupling with the LiO2-like component based on density functional calculations. These new results on the LiO2-like component from Raman spectroscopy provide evidence that a late stage disproportionation mechanism can occur during discharge and add new understanding to the complexities of possible processes occurring in Li-O2 batteries.

DOI: 10.1021/jz501323n

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Cite this paper

@article{Zhai2014RamanEF, title={Raman Evidence for Late Stage Disproportionation in a Li-O2 Battery.}, author={Dengyun Zhai and H Hau Wang and Kah Chun Lau and Jing Gao and Paul C. Redfern and Feiyu Kang and Baohua Li and Ernesto Indacochea and Ujjal Das and Ho-hyun Sun and Ho-Jin Sun and Khalil Amine and Larry A. Curtiss}, journal={The journal of physical chemistry letters}, year={2014}, volume={5 15}, pages={2705-10} }