Improved electrochemical performance of LiFePO₄/C cathode via Ni and Mn co-doping for lithium-ion batteries

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• 作者：Hongbo Shu ; Xianyou Wang ; ^{wxianyou@yahoo.com} ; Qiang Wu ; Benan Hu ; Xiukang Yang ; Qiliang Wei ; Qianqian Liang ; Yansong Bai ; Meng Zhou ; Chun Wu ; Manfang Chen ; Aiwen Wang ; Lanlan Jiang
• 关键词：Lithium ion batteries ; Lithium iron phosphate ; Nickel and manganese co-doping ; High-temperature solid-state route ; Electrochemical performance
• 刊名：Journal of Power Sources
• 出版年：2013
• 出版时间：1 September, 2013
• 年：2013
• 卷：237
• 期：Complete
• 页码：149-155
• 全文大小：1849 K

文摘

The pristine LiFePO₄/C and Ni and Mn co-doping LiFe_1?x?yNi_xMn_yPO₄/C (x?=?0.01-0.04; y?=?0.04-0.01) composites are synthesized for the first time by a simple high-temperature solid-state route. The structure, morphology and electrochemical performance of the samples are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscope (SEM), charge/discharge tests and electrochemical impedance spectroscopy (EIS). The results indicate that the Ni and Mn co-doping does not destroy the olivine structure of LiFePO₄, but it can stabilize the crystal structure, lengthen the Li-O bond, decrease charge transfer resistance, enhance Li ion diffusion velocity, and thus improve its cycling and high-rate capability of the LiFePO₄/C. Especially, the LiFe_0.95Ni_0.02Mn_0.03PO₄/C shows the best cycling stability and rate capability among all the doped samples. The first discharge capacity of LiFe_0.95Ni_0.02Mn_0.03PO₄/C is 145.4?mAh?g^?1 with the capacity retention ratio of 98.6 % till 100 cycles at 1C. Even at a high rate of 10C, it still reveals a high discharge capacity of 115.2?mAh?g^?1.