In-situ synchrotron X-ray absorption studies of LiMn0.25Fe0.75PO4 as a cathode material for lithium ion batteries |
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| Authors: | Yi-Chun Chen Jin-Ming Chen Chia-Haw Hsu Jyh-Fu Lee Jien-Wei Yeh Han C Shih |
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| Institution: | aDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan;bMaterials and Chemical Engineering, Industrial Technology Research Institute, Chutung 310, Taiwan;cNational Synchrotron Radiation Research Center, Hsinchu 300, Taiwan;dInstitute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan |
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| Abstract: | Recently, lithium bi-metal phosphates (LiM′M″PO4) have been synthesized for use as cathode materials in order to increase cell voltages and electrical performances. In this work, we have substituted Mn2+ at the 4c site of LiFePO4 to prepare the lithium bi-metal phosphate LiMn0.25Fe0.75PO4 and have found that it greatly enhances the cell voltage. At a 0.05 C discharge rate, the cell capacity was about 153 mAhg− 1 and the average working voltage rose to 3.53 V due to the Mn substitution. However, the capacity and working voltage both decrease as the discharge rate increases. By in-situ metal K-edge absorption analysis, it reveals that the substituted metal Mn2+ does not work completely at a higher discharge rate, due to poor electrical conductivity and a serious Jahn–Teller effect. |
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| Keywords: | X-ray absorption Olivine structure Lithiation mechanism Jahn– Teller effect Lithium ion batteries |
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