Enhanced low-temperature performance of slight Mn-substituted LiFePO_4/C cathode for lithium ion batteries  

作　　者：ZENG LingJie GONG Qiang LIAO XiaoZhen HE Li HE YuShi MA ZiFeng 

机构地区：[1]Department of Chemical Engineering, Institute of Electrochemical & Energy Technology, Shanghai Jiao Tong University, Shanghai 200240,China

出　　处：《Chinese Science Bulletin》2011年第12期1262-1266,共5页

基　　金：supported by the National Natural Science Foundation of China (20773087);the National Basic Research Program of China (2007CB209705);the Science and Technology Commission of Shanghai Municipality (09XD1402400, 09DZ1203603 and 09HJS000100)

摘　　要：Low temperature performance of LiFePO4/C cathode was remarkably improved by slight Mn-substitution. Electrochemical measurements showed that about 95% of the discharge capacity of LiFe0.98Mn0.02PO4/C cathode at 20°C was obtained at 0°C, compared to 85% of that of LiFePO4/C cathode. The LiFe0.98Mn0.02PO4/C sample also presented enhanced rate performance at –20°C with the discharge capacities of 124.4 mA h/g (0.1C), 99.8 mA h/g (1C), 80.7mAh/g (2C) and 70 mA h/g (5C), respectively, while pristine LiFePO4/C only delivered capacities of 120.5 mA h/g (0.1C), 90.7 mA h/g (1C), 70.4 mA h/g (2C) and 52.2 mA h/g (5C). Cyclic voltammetry measurements demonstrated an obvious improvement of the lithium insertion-extraction process of the LiFePO4/C cathode by slight Mn-substitution. The results of FSEM observation and electrical conductivity measurement indicated that slight Mn-substitution minimized the particle size of LiFe0.98Mn0.02PO4/C and also obviously improved the electrical conductivity of the compound, thus obviously enhances the interface reaction process on the cathode.Low temperature performance of LiFePO4/C cathode was remarkably improved by slight Mn-substitution. Electrochemical measurements showed that about 95% of the discharge capacity of LiFe0.98Mn0.02PO4/C cathode at 20℃ was obtained at 0℃, compared to 85% of that of LiFePO4/C cathode. The LiFe0.98Mn0.02PO4/C sample also presented enhanced rate performance at -20℃ with the discharge capacities of 124.4 mA h/g （0.1C）, 99.8 mA h/g （1C）, 80.7mAh/g （2C） and 70 mA h/g （5C）, respectively, while pristine LiFePO4/C only delivered capacities of 120.5 mA h/g （0.1C）, 90.7 mA h/g （1C）, 70.4 mA h/g （2C） and 52.2 mA h/g （5C）. Cyclic voltammetry measurements demonstrated an obvious improvement of the lithium insertion-extraction process of the LiFePO4/C cathode by slight Mn-substitution. The results of FSEM observation and electrical conductivity measurement indicated that slight Mn-substitution minimized the particle size of LiFe0.98Mn0.02PO4/C and also obviously improved the electrical conductivity of the compound, thus obviously enhances the interface reaction process on the cathode.

关 键 词：磷酸铁锂 低温性能 电池正极 锰取代 锂离子 LIFEPO4 放电容量 电化学测量 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ333.93[化学工程—橡胶工业]