石墨烯的制备及其复合导电浆料对LiNi0.5Co0.2Mn0.3O2锂离子电池性能的影响

通过化学氧化-热还原法制备了高柔韧性、片层少的石墨烯粉体，将其与碳纳米管、炭黑制备出石墨烯复合导电浆料，并分析对比了不同片径的石墨烯复合导电浆料和常规复合导电浆料对LiNi_0.5Co_0.2Mn_0.3O₂锂离子电池性能的影响。结果表明，石墨烯含有丰富的含氧官能团，复配后的石墨烯复合导电浆料在正极材料LiNi_0.5Co_0.2Mn_0.3O₂中可以构建高效的点-线-面结构的三维空间导电网络，其中，D₅₀片径为11.581 μm的石墨烯复合导电浆料电化学性能较为优异，在8C(20 A)大倍率放电条件下容量保持率为104.45%，1C/8C倍率循环200周后电池仍有2 121 mAh的容量，容量保持率为87.90%。

Preparation of Graphene and Effect of Its Composite Conductive Paste on Performance of Li-ion Batteries with LiNi0.5Co0.2Mn0.3O2 Cathode Material

A kind of graphene powder with high flexibility and few layer was firstly prepared by a combined processing technique of chemical oxidation and thermal reduction, and then mixed with carbon nanotubes and carbon black to form a kind of graphene composite conductive paste. Based on the analysis and comparison of the effects of graphene with different particle sizes and conventional composite conductive paste on the electrochemical properties of Li-ion batteries with LiNi_0.5Co_0.2Mn_0.3O₂ cathode material, it is found that the graphene is rich in oxygen-containing functional groups, and the prepared graphene composite conductive paste can construct a three-dimensional conductive network with point-line-plane structure in the graphene composites conductive paste. The graphene composite conductive paste with particle size (D₅₀) of 11.581 μm presents excellent electrochemical performance, showing that the capacity retention rate is 104.45% when discharged at 8C (20 A) rate. The battery has its capacity remaining at 2 121 mAh after 200 cycles of charge/discharge at 1C/8C rate, with a retention rate of 87.90%.