商品化石墨作为聚合物锂离子电池负极材料的性能表征

采用商品化中间相碳微球(MCMB)及人造石墨与中间相碳微球的混合体作为聚合物锂离子电池的负极材料,通过SEM、XRD对比研究了两种负极材料电化学循环前后的微观形貌和相结构,测试了两种聚合物锂离子电池的倍率放电性能和循环寿命,并通过交流阻抗谱分析了两种负极材料的电化学性能差异.结果表明:掺入人造石墨后,中间相碳微球的平均粒径和比表面积增大,电化学循环200次后的晶面间距减小、石墨化度增大,倍率放电性能降低,电荷转移电阻及锂离子扩散阻抗均增大,循环性能得到较大提高.

The performance characterization of commercial graphite as negative electrodes of polymer lithium ion batteries

Commercial mesocarbon micro beads(MCMB) and its mixture with artificial graphite were investigated as negative electrodes of polymer lithium ion batteries.The morphology and phase structures of the two type of graphite were studied by SEM and XRD before and after electrochemically cyclic treatment.The high-rate dischargeability(HRD) and cyclic lives of the above polymer lithium ion batteries were examined as well as their EIS spectra to further explore their electrochemical performances.The results show that with the addition of artificial graphite,the average particle size,specific surface area and cyclic performance of MCMB increase and after cycling for 200 times it displays higher graphitization degree,higher charge transfer resistance and lithium diffusion impedance.However,the rate dischargeability and crystal distance of experimental graphite decrease during electrochemical cycles.