TY - JOUR
T1 - Defect chemical studies on oxygen release from the Li-rich cathode material Li 1.2 Mn 0.6 Ni 0.2 O 2-δ
AU - Nakamura, Takashi
AU - Gao, Hongze
AU - Ohta, Kento
AU - Kimura, Yuta
AU - Tamenori, Yusuke
AU - Nitta, Kiyofumi
AU - Ina, Toshiaki
AU - Oishi, Masatsugu
AU - Amezawa, Koji
N1 - Funding Information:
This work was supported by the Grand-in-Aid for Scientic Research (C), Grant number JP18K05288 and Cooperative Research Program of the “Network Joint Research Center for Materials and Devices”. The synchrotron radiation experiments were performed at BL01B1 and BL27SU of SPring-8 with the approval of JASRI (Proposal No. 2016B1143, 2016B1210, 2017A1417, 2017A1736).
Publisher Copyright:
© 2019 The Royal Society of Chemistry.
PY - 2019
Y1 - 2019
N2 - Oxygen release from oxide-based cathode materials is a key phenomenon for the realization of high performance and highly reliable next-generation batteries, because it can be a trigger for a thermal runaway and closely related to electrochemical performances. In this study, the mechanism of oxygen release from Li 1.2 Mn 0.6 Ni 0.2 O 2-δ and the corresponding electronic and crystal structural changes were studied. Li 1.2 Mn 0.6 Ni 0.2 O 2-δ showed oxygen deficient nonstoichiometry until δ ≈ 0.042, and further oxygen extraction resulted in the reductive decomposition to MnNi 6 O 8 and Li-Mn enriched Li(Li,Mn,Ni)O 2-δ′ . The oxygen vacancy formation mechanism was investigated by the defect chemical and thermodynamic analyses, and the oxygen vacancy formation energy was calculated from the nonstoichiometric data (ca. 2.03 eV). It was clearly confirmed that the lattice parameters and the distances of Mn-O and Ni-O were increased by the oxygen vacancy formation, which is known as the reduction expansion in nonstoichiometric compounds. Cooperative reduction of Ni, Mn and O due to the oxygen vacancy formation was observed from Ni-L, Mn-L and O-K edge X-ray absorption spectra. The charge compensation of the oxygen vacancy formation was maintained mainly by the reduction of Ni 3+ to Ni 2+ and mildly by the reduction of Mn 4+ and O 2- .
AB - Oxygen release from oxide-based cathode materials is a key phenomenon for the realization of high performance and highly reliable next-generation batteries, because it can be a trigger for a thermal runaway and closely related to electrochemical performances. In this study, the mechanism of oxygen release from Li 1.2 Mn 0.6 Ni 0.2 O 2-δ and the corresponding electronic and crystal structural changes were studied. Li 1.2 Mn 0.6 Ni 0.2 O 2-δ showed oxygen deficient nonstoichiometry until δ ≈ 0.042, and further oxygen extraction resulted in the reductive decomposition to MnNi 6 O 8 and Li-Mn enriched Li(Li,Mn,Ni)O 2-δ′ . The oxygen vacancy formation mechanism was investigated by the defect chemical and thermodynamic analyses, and the oxygen vacancy formation energy was calculated from the nonstoichiometric data (ca. 2.03 eV). It was clearly confirmed that the lattice parameters and the distances of Mn-O and Ni-O were increased by the oxygen vacancy formation, which is known as the reduction expansion in nonstoichiometric compounds. Cooperative reduction of Ni, Mn and O due to the oxygen vacancy formation was observed from Ni-L, Mn-L and O-K edge X-ray absorption spectra. The charge compensation of the oxygen vacancy formation was maintained mainly by the reduction of Ni 3+ to Ni 2+ and mildly by the reduction of Mn 4+ and O 2- .
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U2 - 10.1039/c8ta12484a
DO - 10.1039/c8ta12484a
M3 - Article
AN - SCOPUS:85062269737
VL - 7
SP - 5009
EP - 5019
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
SN - 2050-7488
IS - 9
ER -