Investigation of the Charge Compensation Mechanism on the Electrochemically Li-Ion Deintercalated Li1-xCo1/3Ni1/3Mn1/3O2 Electrode System by Combination of Soft and Hard X-ray Absorption Spectroscopy

• Published in: Journal of the American Chemical Society Vol. 127; no. 49; pp. 17479 - 17487
• Main Authors: YOON, Won-Sub, BALASUBRAMANIAN, Mahalingam, CHUNG, Kyung Yoon, YANG, Xiao-Qing, MCBREEN, James, GREY, Clare P., FISCHER, Daniel A.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.12.2005
• Subjects: ABSORPTION SPECTROSCOPY; Applied sciences; ATOMIC AND MOLECULAR PHYSICS; CATHODES; CHARGE STATES; COBALT IONS; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; ELECTRODES; Exact sciences and technology; MANGANESE IONS; national synchrotron light source; OXIDATION; OXYGEN; REDOX PROCESS; Cobalt oxide; Alkali metal Compounds; XANES spectrometry; Transition metal Compounds; Secondary cell; Electrode material; Electric batteries; Discharge charge cycle; EXAFS spectrometry; Multi-element compound; Intercalation compound; Metal metal oxide batteries; Charge compensation; Manganese oxides; Electronic structure; Organic electrolyte storage battery; Lithium oxide; Specific capacity; Nickel oxide; Electrical characteristic
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0530568

In situ hard X-ray absorption spectroscopy (XAS) at metal K-edges and soft XAS at O K-edge and metal L-edges have been carried out during the first charging process for the layered Li1-xCo1/3Ni1/3Mn1/3O2 cathode material. The metal K-edge XANES results show that the major charge compensation at the metal site during Li-ion deintercalation is achieved by the oxidation of Ni2+ ions, while the manganese ions and the cobalt ions remain mostly unchanged in the Mn4+ and Co3+ state. These conclusions are in good agreement with the results of the metal K-edge EXAFS data. Metal L-edge XAS results at different charge states in both the FY and PEY modes show that, unlike Mn and Co ions, Ni ions at the surface are oxidized to Ni3+ during charge, whereas Ni ions in the bulk are further oxidized to Ni4+ during charge. From the observation of O K-edge XAS results, we can conclude that a large portion of the charge compensation during Li-ion deintercalation is achieved in the oxygen site. By comparison to our earlier results on the Li1-xNi0.5Mn0.5O2 system, we attribute the active participation of oxygen in the redox process in Li1-xCo1/3Ni1/3Mn1/3O2 to be related to the presence of Co in this system.