作　　者： ; ; ; ;

机构地区： 兰州理工大学材料科学与工程学院甘肃省有色金属新材料省部共建国家重点实验室

出　　处： 《电化学》 2012年第4期337-341,共5页

摘　　要： 本文采用碳热还原法,以廉价的FeCl3.6H2O、LiOH.H2O和NH4H2PO4为原料,以淀粉为还原剂和碳源,经600℃烧结制备了LiFePO4/C复合材料,方法重现性好且易规模化生产.采用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)测试材料结构,观察材料形貌.结果表明,经600℃烧结10 h所得产物具有纯相的橄榄石型晶体结构,良好的结晶性和规整的球状形貌,粒径为60～100 nm.包覆LiFePO4晶粒的碳层厚度为2 nm左右,碳含量为5%(by mass).材料的振实密度高达1.3 g·cm-3,在0.2C倍率下首次放电比容量为162 mAh·g-1,在0.5C、1C、2C、5C和10C倍率下首次放电比容量分别为143、135、127、116和105 mAh·g-1,10C倍率下500周期循环,其比容量仍有81 mAh·g-1. The LiFePO4/C composite electrode material was synthesized by a moderate in situ carbothermal reduction method at 600 ℃ using FeC13 .6H20, LiOH. H20 and NH4H2PO4 as starting materials, soluble starch sol as a carbon source and a reducing agent. This method is readily reproducible and possibly feasible to carry out large-scale synthesis. The structure and morphology of the LiFePOJC samples were investigated by X- ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The synthesized LiFePO4/C composite was in pure phase of olivine-type, shows highly crystalline and spherical morphology with the particle sizes in the range of 60 - 100 nm. The thickness of the carbon film could be as thin as about 2 nm for the isolated LiFePOJC particles, and the amount of carbon introduced into the composite was about 5% （by mass）. The measured tap density of LiFePO4/C composite was as high as 1.3 g·cm^-3 and the initial discharge capacities of LiFePO4/C composite reached 162, 143, 135, 127, 116 and 105mAh·g^-1 at 0.2C, 0.5C, 1C, 2C, 5C and 10C rates, respectively. Remarkably, even after 500 cy-cles at 10C, the capacity of 81 mAh·g^-1 could be obtained.

关 键 词： 锂离子电池 正极材料 核 壳结构

领　　域： [理学] [理学] [电气工程]