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DOI£º10.11918/j.issn.0367-6234.2013.07.022

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Effects of Mnª¬ª©2+ªª doping on structure, performance and kinetic of lithium-ion insertion of LiFePO₄ positive-electrode material

YI Tingfeng^1,2,3, ZHU Yanrong¹, SHEN Haoyu^2,3, MA Yongquan^2,3, ZUO Pengjian², ZHU Rongsun¹ª¤

(1. School of Chemistry and Chemical Engineering, Anhui University of Technology, 243002 Maanshan, Anhui, China;ª¤ 2. School of Chemical Engineering, Harbin Institute of Technology, 150001 Harbin, China;ª¤ 3. Chilwee Power Co., Ltd, 313100 Huzhou, Zhejiang, China)ª¤ª¤

Abstract:

To improve the performance of olivine LiFePO₄ positive-electrode material, the Mn-doped ª§ª«LiMnª«_xª«Feª«ª­ª©1-xªªª«POª«₄(x=ª§0,0.0,0.5,0.0,0.50) materials were prepared by a solid-state reaction method. The structure, electrochemical performance and lithium ion insertion-extraction kinetic of the material are investigated by scanning electron microscopy (SEM), X-ray diffractometry (XRD), charge-discharge tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the Mn-doped LiFePO₄ material powders have a uniform morphology, a small particle size and narrow particle size distribution, and ª§ª«LiMnª«_xª«Feª«ª­ª©1-xªªª«POª«₄ª§ materials are pure phase olivine structure. LiMnª­ª©0.4ªªFeª­ª©0.6ªªPO₄ shows the highest discharge capacity and the best kinetic performance among all samples at different rates. The Mn doping improves the reversibility, Liª¬+ions diffusion coefficient and discharge capacity, and reduces the charge transfer resistance, and then increase the kinetic performance of LiFePO₄ material.ª¤

Key words:  lithium ion battery  positive-electrode material  ª§ª«LiMnª«_xª«Feª«ª­ª©1-xªªª«POª«₄  ª§ kinetic performanceª¤ª¤