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.
出处
《电化学》
CAS
CSCD
北大核心
2012年第4期337-341,共5页
Journal of Electrochemistry
基金
国家自然科学基金项目(No.21163010)
甘肃省高校基本科研业务费专项资金资助
