| Abstract
| - The variation of electronic transitions and local structure of the LiNi1/3Co1/3Mn1/3O2 cathode material during electrochemical cycling was investigated by in-situ X-ray absorption spectroscopy. A short-range ordering between NiII and MnIV on the transition metal layer was found from the EXAFS study.
- In-situ X-ray absorption spectroscopic investigations have been carried out to examine the changes ofthe electronic transitions and local structure at the Mn, Co, and Ni K-edge for the LiNi1/3Co1/3Mn1/3O2electrode during charging and discharging process in this study. It was found that only Ni atom inLi1-xNi1/3Co1/3Mn1/3O2 is electroactive from the evolution of the XANES spectra and the bond lengthvariation of Ni−O. It was found that the redox pairs of Ni2+/Ni3+ and Ni3+/Ni4+ exist and the oxidationstates of Mn and Co remain as MnIV and CoIII, respectively, in Li1-xNi1/3Co1/3Mn1/3O2 upon charge anddischarge. The oxygen, rather than the transition-metal ions (Ni, Co, and Mn), functions as electrondonor at the end of charge. In addition, the irreversible capacity at the first cycle derives mainly from theappearance of inactive Ni, which is evidenced by the energy shift E − E0 of the absorption edge for theNi absorber and the bond length change of the Ni−O. A decrease/increase of Debye−Waller factor ofNi−O contribution results from a decrease/increase of Jahn−Teller active NiIII concentration during cycling.The trends of the variations for the bond length and Debye−Waller factor for the second shell Mn−Mand Ni−M contributions are significant and similar, suggesting the short-range ordering between NiIIand MnIV may take place in this compound.
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