Structure studies on LiMn(0.25)Fe(0.75)PO(4) by in-situ synchrotron X-ray diffraction analysis

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Title:	Structure studies on LiMn(0.25)Fe(0.75)PO(4) by in-situ synchrotron X-ray diffraction analysis
Authors:	Chen, YC (Chen, Yi-Chun) Chen, JM (Chen, Jin-Ming) Hsu, CH (Hsu, Chia-Haw) Yeh, JW (Yeh, Jien-Wei) Shih, HC (Shih, Han C.) Chang, YS (Chang, Yee-Shyi) Sheu, HS (Sheu, Hwo-Shuenn)
Contributors:	化材所
Keywords:	LITHIUM BATTERIES CATHODE MATERIALS LIFEPO4 CATHODE XRD OLIVINES
Date:	2009-04
Issue Date:	2011-12-07 11:50:27 (UTC+8)
Abstract:	In this work, we substituted Mn2(+) at the 4c site of LiFePO(4) to prepare LiMn(0.25)Fe(0.75)PO(4) in order to raise the working voltage. In order to study the phase transformation of lithium bi-metal phosphate (LiM'M '' PO(4)) during the lithiation/delithiation, in-situ synchrotron X-ray diffraction has been used. At 0.05C charge/discharge, X-ray patterns reveal that LiMn(0.25)Fe(0).(75)PO(4) undergoes two two-phase transformations during the delithiation, resulting from Fe(2+)/Fe(3+) and then Mn(2+)/Mn(3+) redox reactions. However, the phase transformation for lithiation is different, becoming a two-phase (Mn(2+)/Mn(3+)) reaction and single-phase (Fe(2+)/Fe(3+)) reaction. Even at a higher charge/discharge rate (0.5C), the results are the same. LiMn(0.25)Fe(0).(75)PO(4) also has a good cyclability, since there is no significant capacity fading during the cycling test. The X-ray patterns reveal that LiMn(0.25)Fe(0.75)PO(4) still maintains a good crystal structure after 40 cycles because of its stable olivine structure. (C) 2008 Elsevier B.V. All rights reserved.
Appears in Collections:	[Department of Chemical & Materials Engineering] journal articles

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