论文部分内容阅读
为提高LiMn_(0.7)Fe_(0.3)PO_4(LMFP)的电化学性能,首先,采用溶剂热法将氧化石墨烯(GO)与LMFP复合,合成了GO/LMFP复合材料;然后,利用XRD和电感耦合等离子体(ICP)对所得样品的结构和元素进行分析,利用SEM对样品的形貌进行表征,利用电池充放电测试系统和电化学工作站对其进行电化学性能测试。结果表明:所得GO/LMFP复合材料呈现单相橄榄石结构;粒径在200nm左右,且分布较均匀。经GO改性后的复合材料在0.2C、0.5C、1.0C、5.0C和10.0C倍率下的首次放电比容量分别为157.9、148.1、142.0、122.3、87.3mAh·g-1,与C/LMFP复合材料相比,分别提高了5.9%、4.7%、7.0%、24.3%和66.6%。所得结论表明GO的加入有效提高了材料的电子电导率和电化学活性,且与无定型碳共同作用,活性物质的有效利用率提高,GO/LMFP复合材料的循环稳定性也得到改善。
In order to improve the electrochemical performance of LiMn_ (0.7) Fe_ (0.3) PO_4 (LMFP), GO / LMFP composites were synthesized by solvothermal method using GO and LMFP. Then, The structures and elements of the obtained samples were analyzed by coupled plasma (ICP). The morphology of the samples was characterized by SEM. The electrochemical performance of the samples was tested by the battery charge - discharge test system and electrochemical workstation. The results show that the obtained GO / LMFP composites have a single phase olivine structure with a particle size of about 200 nm and a uniform distribution. The first discharge capacities of GO modified composites were 157.9, 148.1, 142.0, 122.3 and 87.3 mAh · g-1 at 0.2C, 0.5C, 1.0C, 5.0C and 10.0C respectively, LMFP composites, respectively, increased by 5.9%, 4.7%, 7.0%, 24.3% and 66.6%. The results show that the addition of GO can effectively improve the electronic conductivity and electrochemical activity of the material, and with the interaction of amorphous carbon, the effective utilization of active material is improved, and the cycle stability of GO / LMFP composite is also improved.