LiFePO_4/C复合正极材料的制备及其电化学性能研究  

Synthesis and Electrochemical Properties of LiFePO_4/C Composite Cathode Materials

作　　者：何雨石[1] 廖小珍[1] 马紫峰[1] 原鲜霞[1] 王保峰[1] 蒋逸[2] 

机构地区：[1]上海交通大学,上海200240 [2]上海交通大学分析测试中心,上海200030

出　　处：《稀有金属材料与工程》2007年第9期1644-1648,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(20476055;20206016;50236010);上海市曙光学者计划(03SG12)

摘　　要：采用高温固相碳热还原法(CTR,Carbothermal Reduction)合成了LiFePO4/C复合正极材料。采用XRD,SEM以及BET等方法对产物进行表征。结果表明,所得LiFePO4/C材料有着单一的橄榄石型晶体结构。750℃下制备产物的BET比表面积为39.7002m2/g。利用恒流充放电,循环伏安法(CV),电化学阻抗谱(EIS)等电化学手段研究了LiFePO4/C材料的电化学性质。结果表明:750℃下制备的LiFePO4/C复合材料在25℃工作温度下,有着优异的循环稳定性和大倍率充放电性能,使用850mA/g(5C)的电流密度对电池充放电90次后,电池放电比容量仍能保持111mAh/g。在55℃工作温度下1C充放电倍率时,首次和第90次循环的放电比容量分别为145.3mAh/g和142.9mAh/g。The electroactive LiFePO4/C composite has been synthesized by a high temperature solid-state carbothermal reduction method. The samples were characterized by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM） and Brunauer-Emmett-TeUer （BET）. The XRD analysis indicated an olivine type LiFePOJC product with a pure orthorhombic phase. The BET specific surface area of LiFePO4/C composite prepared at 750 ℃ was 39.7 m^2/g. The electrochemical characteristics of LiFePO4/C composite were evaluated by means of the constant current charge-discharge, cyclic voltammetry （CV） and electrochemical impedance spectroscopy. The experimental results showed that the LiFePOJC composite synthesized at 750 ℃ had a high capacity retention upon cycling and high rate capability at 25 ℃. The obtained specific discharge capacity was 111 mAh/g after 90 cycle by applying a higher charge/discharge current density of about 850 mA/g （5 C） at 25 ℃. At 55 ℃, the specific discharge capacities of the first and the 90th cycle were 145.3 mAh/g and 142.9 mAh/g, respectively, at the charge/discharge current density of 170 mA/g （1C）.

关 键 词：LIFEPO4 正极材料 碳热还原法 锂离子电池 

分 类 号：TM910.4[电气工程—电力电子与电力传动]