Phase Stability of Lithium Manganese Oxide Stored at High Temperatures. Issue 9 (1st January 2016)

• Record Type: Journal Article
• Authors: Nishijima, Manabu; Hamana, Masayuki; Saito, Takamitsu; Nitta, Yoshiaki; Hirayama, Masaaki; Kanno, Ryoji
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 9(2016)
• Page Start: A1841
• Page End: A1845
• Publication Date: 2016-01-01
• Subjects: High-temperature storage -- LiMn2O4 -- Lithium-ion battery -- Phase stability -- X-ray absorption fine structure -- X-ray diffraction; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0321609jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Capacity degradation of the LiMn2 O4 cathode during high-temperature storage was investigated for various lithium contents. The capacity recovery rate was determined after the storage test, and the phases and valence state of manganese ions were investigated by X-ray diffraction and X-ray absorption fine structure. The storage characteristics depend on the state of charge (SOC); a significantly low recovery rate was found for the shallow SOC region of LiMn2 O4 . The phase changes determined after the deterioration were as follows. (i) The lattice parameters decrease with an increase in manganese valence, caused by the formation of defects at the 16 d site due to manganese dissolution. (ii) A new phase forms as a second phase. This phase has higher manganese valence and a larger amount of manganese vacancies. The same type of phase was produced by a high-temperature treatment of the shallow SOC phase at 150°C, which indicates that the phase was stable at high temperatures. (iii) A lower manganese valence state was observed at the spinel surface, which is related to manganese dissolution. Deterioration in the shallow SOC region during high-temperature storage is related to the phase stability of the de-intercalated spinel phases.