Resonant photoemission spectroscopy of the cathode material LixMn0.5Fe0.5PO4 for lithium-ion battery

• Published in: Journal of power sources Vol. 226; pp. 42 - 46
• Main Authors: Kurosumi, Shodai, Horiba, Koji, Nagamura, Naoka, Toyoda, Satoshi, Kumigashira, Hiroshi, Oshima, Masaharu, Furutsuki, Sho, Nishimura, Shin-ichi, Yamada, Atsuo, Mizuno, Noritaka
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-03-2013; Elsevier
• Subjects: Applied sciences; Cathode material; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Lithium-ion battery; Materials; Olivine-type; Resonant photoemission spectroscopy; Cathode material; Lithium-ion battery; Resonant photoemission spectroscopy; Olivine-type; Oxygen; Cathode; Alkaline storage battery; Secondary cell; Transition metal; Electrode material; Lithium battery; Charge compensation; Electronic structure; Photoemission; Oxidation; Strength; X ray absorption
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.10.041

We have investigated the change in the electronic structure of LixMn0.5Fe0.5PO4 through the charge process, especially in the transition metal partial DOS using X-ray absorption and resonant photoemission spectroscopy measurements. The oxidation reaction between Fe2+ and Fe3+ proceeds while the 0.5 Li ions are extracted from LiMn0.5Fe0.5PO4. Moreover, comparing resonant photoemission spectra of LixMn0.5Fe0.5PO4 with those of LixFePO4, we have found that both spectral line-shapes are almost identical, suggesting that the strong localization of the Fe 3d states in the LiMn0.5Fe0.5PO4 system. On the other hand, in Mn 2p–3d X-ray absorption and resonant photoemission spectra, the Mn oxidation reaction from Mn2+ to Mn3+ partially occurs and Mn 3d states of LixMn0.5Fe0.5PO4 remain almost unchanged through the charge reaction. Reflecting the difference in the strength of the interaction between the transition metal Fe or Mn ions and the oxygen ions, it is suggested that although the oxidation from Fe2+ to Fe3+ proceeds largely on Fe ions during the charge reaction from x = 1.0 to 0.5, the charge compensation for the electron exchange mainly occurs not only at the Mn ions but also at the poly-anion sites during the charge reaction from x = 0.5 to 0.
► We reveal the element-specific electronic structure of LixMn0.5Fe0.5PO4. ► Changes in the Fe 3d states of LixMn0.5Fe0.5PO4 are identical with those of LixFePO4. ► Mn 3d states of LixMn0.5Fe0.5PO4 remain unchanged through the charge reaction.