CHENG, Ju-Hsiang; PAN, Chun-Jern; LEE, Jyh-Fu; CHEN, Jin-Ming; GUIGNARD, Marie; DELMAS, Claude; CARLIER-LARREGARAY, Dany; HWANG, Bing-Joe

doi:10.1021/cm403597h

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CHENG, Ju-Hsiang
Department of Chemical Engineering

PAN, Chun-Jern
Department of Chemical Engineering

LEE, Jyh-Fu
Department of Chemical Engineering

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Chemistry of Materials. 2014, vol. 26, n° 2, p. 1219-1225

American Chemical Society

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Sodium intercalation in P2-Na2/3Co2/3Mn1/3O2 (obtained by a coprecipitation method) was investigated by ex situ and in situ X-ray absorption spectroscopy. The electronic transitions at the O K-edge and the charge compensation mechanism, during the sodium intercalation process, were elucidated by combining Density Function Theory (DFT) calculations and X-ray absorption spectroscopy (XAS) data. The pre-edge of the oxygen K-edge moves to higher energy while the integrated intensity dramatically decreases, indicating that the population of holes in O 2p states is reduced with increasing numbers of sodium ions. From the K-edge and L-edge observations, the oxidation states of pristine Co and Mn were determined to be +III and +IV, respectively. The absorption energy shifts to lower positions during the discharging process for both the Co and the Mn edges, suggesting that the redox pairs, that is, Co3+/Co2+ and Mn4+/Mn3+, are both involved in the reaction.< Réduire

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Simultaneous Reduction of Co3+ and Mn4+ in P2-Na2/3Co2/3Mn1/3O2 As Evidenced by X‑ray Absorption Spectroscopy during Electrochemical Sodium Intercalation

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