Charge compensation mechanisms in Li_1.16Ni_0.15Co_0.19Mn_0.50O₂ positive electrode material for Li-ion batteries analyzed by a combination of hard and soft X-ray absorption near edge structure

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• 作者：Masatsugu Oishi ; Takahiro Fujimoto ; Yu Takanashi ; Yuki Orikasa ; Atsushi Kawamura ; Toshiaki Ina ; Hisao Yamashige ; Daiko Takamatsu ; Kenji Sato ; Haruno Murayama ; Hajime Tanida ; Hajime Arai ; Hideshi Ishii ; Chihiro Yogi ; Iwao Watanabe ; Toshiaki Ohta ; Atsushi Mineshige ; Yoshiharu Uchimoto ; Zempachi Ogumi
• 关键词：Li2MnO3 ; Lithium ion battery ; In situ XAS ; Positive material
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：222
• 期：Complete
• 页码：45-51
• 全文大小：632 K

文摘

The redox reaction of Li_1.16Ni_0.15Co_0.19Mn_0.50O₂ positive electrode material during the charging and discharging processes was investigated by using spectroscopic methods, i.e. in situ hard X-ray absorption near edge structure (XANES) at transition metal K-edges and ex situ soft XANES at oxygen K- and transition metal L-edges. The spectral changes of constituent elements during the initial charging to 4.5?V vs. Li/Li⁺ are quite similar to those of conventional layer-structured positive materials, such as LiNi_1/3Mn_1/3Co_1/3O₂. Ni²⁺ and Co³⁺ ions are fully oxidized to Ni⁴⁺ and Co⁴⁺, while Mn⁴⁺ remains unchanged. Ligand oxygen ions also take part in charge compensation. In the process of charging to 4.8?V via the plateau voltage region, no significant spectral change appears except partial reduction of Ni and Co ions in spite of lithium extraction. By discharging to 2.0?V the spectra of each element return to those of the pristine material.