Structure and Electrochemical Performances of LiFePO4/C Composite Cathode Coating with Different Carbon Sources for Lithium Ion Batteries
首发时间:2012-11-27
Abstract:Three kinds of carbon resources, poly(vinyl alcohol), phenol-formaldehyde resin and epoxy resin, were used to prepare the LiFePO4/C composite (LFPC-1, LFPC-2, LFPC-3). XRD patterns show that the LFPC composites possess the typical olivine structure. The particle size and the reunited degree of LFPC-1 are smaller than those of LFPC-2 and LFPC-3. The discharge capacities of LFPC-1 at different C-rates are also much higher than those of the other two samples. Its discharge capacities at 0.1 C and 1 C are 158.8 mAh g-1 and 136.20 mAh g-1. Its discharge curve can maintain the stable potential platform of 3.3 V at the rate of 1 C. LFPC-1 possesses the highest electrical conductivity of 5.76×10-2 S cm-1. This is because the ID/IG value of 1.20 in Raman spectra is much lower than that of LFPC-2 and LFPC-3. The selected area electron diffraction in the HRTEM of LFPC-1 shows directly that the graphitized carbon is formed on the cover surface of LFPC-1 composite.
keywords: lithium ion batteries lithium iron phosphate carbon resources electrical conductivity electrochemical performances
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不同碳源包覆的锂离子电池正极材料LiFePO4/C的结构和电化学性能
摘要:选择聚乙烯醇、酚醛树脂和环氧树脂等三种碳源用于制备LiFePO4/C复合材料(LFPC-1、LFPC-2和LFPC-3)。XRD图谱分析表明LFPC复合材料具有典型的橄榄石结构。LFPC-1试样中的颗粒尺寸和团聚程度明显小于LFPC-2和LFPC-3. LFPC-1试样在不同倍率时的放电容量也都比另外两个试样高,其在0.1 C和1 C时的放电容量分别为158.8 mAh g-1和136.20 mAh g-1;在1 C时它的放电曲线仍能保持3.3 V的稳定电位平台。LFPC-1试样具有最高的电子电导率5.76×10-2 S cm-1. 这是由于LFPC-1的ID/IG值(1.20)要明显低于LFPC-2和LFPC-3试样。LFPC-1试样HRTEM中的选区电子衍射直接证明了LFPC-1复合材料的表面形成了石墨化的碳材料。
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