Preparation and electrochemical properties of homogeneous carbon-coated LiFe0.9Mn0.1PO4 as cathode material for lithium-ion batteries

• Published in: Journal of the Brazilian Chemical Society Vol. 23; no. 7; pp. 1298 - 1304
• Main Authors: Xu, Yang, Yu, Jingang, Peng, Sui, Liu, Suqin, Wei, Zhongqiang, Li, Xianhong, Li, Yajuan
• Format: Journal Article
• Language: English
• Published: Sociedade Brasileira de Química 01.07.2012
• Subjects: CHEMISTRY, MULTIDISCIPLINARY; lithium-ion batteries; cathode material; Mn-doping; LiFePO4
• ISSN: 0103-5053; 1678-4790
• DOI: 10.1590/S0103-50532012000700014

Homogeneous carbon-coated LiFe0.9Mn0.1PO4 cathode material was synthesized by one-step solid-state reaction using glucose as carbon source. Powder X-ray diffractometry (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic measurements were employed to characterize the samples. Mn-doping and carbon co-modification did not affect the olivine structure of LiFePO4, but improved its kinetics in terms of capacity delivery, polarization and rate capability. When compared with the undoped LiFePO4/C, the LiFe0.9Mn0.1PO4/C sample presented good size distribution - around 100-200 nm - and better electrochemical performance. At current rates of 0.1, 1.0, 3.0 and 10.0 C (C = 170 mA g-1), the LiFe0.9Mn0.1PO4/C electrode delivered discharge capacities of 154.1, 138.8, 120.0 and 94.0 mA h g-1, respectively. Results obtained by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that the polarization and charge transfer resistance of the sample were greatly decreased by Mn-doping.