Effects of Carbon on Structure and Electrochemical Performance of Li2FeSiO4 Cathode Materials for Lithium-ion Batteries
首发时间:2012-01-11
Abstract:Li2FeSiO4/C composite cathode material was prepared by solid-state method with sucrose as carbon source. The effects of carbon content on structure and electrochemical performance of Li2FeSiO4/C cathode materials for lithium-ion batteries were investigated. The materials were characterized comparatively by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. The SEM images showed that the Li2FeSiO4/C consists of partially agglomerated nanoparticles with an average particle size of 100 nm. TEM images confirmed that a carbon layer was formed on the surface of Li2FeSiO4/C particles, which aimed to enhance the electronic conductivity of the material as well as inhibit the agglomeration during annealing process. The electrochemical measurement results revealed that the Li2FeSiO4/C composite with 7.5wt % carbon shows a good electrochemical performance with an initial discharge capacity of 141 mAhog-1 at 0.1C, and remains a discharge capacity of 103.6 mAhog-1 at 0.5C after 50 cycles.
keywords: lithium ion battery cathode material Li2FeSiO4/C solid-state method electrochemical performance
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碳含量对Li2FeSiO4材料结构和电化学性能的影响
摘要:本论文以蔗糖作为碳源制备了Li2FeSiO4/C正极材料,研究了碳含量对材料的结构和电化学性能的影响。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、恒流充放电测试、电化学交流阻抗谱(EIS)以及循环伏安(CV)等对材料进行了物理结构表征和电化学性能测试。SEM结果显示材料的平均粒径为100nm,TEM显示材料纳米Li2FeSiO4晶体分散在碳网络结构中,这导致了材料电导率的提高。电化学测试结果表明Li2FeSiO4/C材料中碳含量在7.5wt%时具有优异的电化学性能,材料0.1C下的首次放电容量达到141 mAhog-1,0.5C条件下经过50个循环容量还保持在103.6 mAhog-1。
关键词: 锂离子电池 正极材料 Li2FeSiO4/C 固相法 电化学性能
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