Synthesis of LiFePO_4 /C as cathode material by a novel optimized hydrothermal method  

作　　者：GAO Ge LIU Aifang HU Zhonghua XU Yuanyuan LIU Yafei 

机构地区：[1]Department of Chemistry, Tongii University, Shanghai 200092, China

出　　处：《Rare Metals》2011年第5期433-438,共6页稀有金属（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 50472089)

摘　　要：Olivine LiFePO 4 , as a cathode material for lithium ion batteries, was prepared by a novel optimized hydrothermal method; afterwards, the product mixed with glucose was two-step （350℃ and 700℃） calcinated under high-purity N 2 atmosphere to obtain the LiFePO 4 /C composite. The study on the hydrothermal preparation method, which focused on the influences of molar ratios, initial pH value, reaction temperature, and duration, was made to promote the resultant performances and to investigate the relations between the performances and the reaction conditions. The resultant samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and electrochemical tests, which include charge-discharge, electrochemical impedance spectroscopy, and cyclic voltammetry. The result shows that the optimal hydrothermal condition is to set the Li：Fe：P molar ratio at 3：1：1 and the reaction temperature at 180℃ for 5 h duration with an initial pH value of 7. The optimized sample, with an average particle size of 100 to 300 nm and a discharge capacity of 118.2 mAh·g-1 at 0.1C, exhibits a stable and narrow-gapped charge-discharge platform and small capacity losses after cycles.Olivine LiFePO 4 , as a cathode material for lithium ion batteries, was prepared by a novel optimized hydrothermal method; afterwards, the product mixed with glucose was two-step （350℃ and 700℃） calcinated under high-purity N 2 atmosphere to obtain the LiFePO 4 /C composite. The study on the hydrothermal preparation method, which focused on the influences of molar ratios, initial pH value, reaction temperature, and duration, was made to promote the resultant performances and to investigate the relations between the performances and the reaction conditions. The resultant samples were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and electrochemical tests, which include charge-discharge, electrochemical impedance spectroscopy, and cyclic voltammetry. The result shows that the optimal hydrothermal condition is to set the Li：Fe：P molar ratio at 3：1：1 and the reaction temperature at 180℃ for 5 h duration with an initial pH value of 7. The optimized sample, with an average particle size of 100 to 300 nm and a discharge capacity of 118.2 mAh·g-1 at 0.1C, exhibits a stable and narrow-gapped charge-discharge platform and small capacity losses after cycles.

关 键 词：lithium ion batteries cathode materials PHOSPHATES OLIVINE carbon deposition hydrothermal synthesis 

分 类 号：TM912.2[电气工程—电力电子与电力传动] TB383[一般工业技术—材料科学与工程]