Effect of binary composite conductive agent with graphene and carbon nanotube on performance of LiNi_0.5Co_0.2Mn_0.3O₂ lithium-ion battery

In this paper, graphene (Gen), carbon nanotubes (CNTs) and their composite materials graphene/carbon nanotubes (Gen/CNTs) were added to LiNi_0.5Co_0.2Mn_0.3O₂ in different contents and proportions to prepare soft pack batteries. The combination between different conductive agents and anode materials and the content ratio of conductive agents on the performance of lithium-ion batteries were studied by XRD, SEM and electrochemical performance tests. Experimental results show that the performance of the battery is closely related to the content of the conductive agent, and the performances of the composite conductive agents are better than those of the single conductive agents. Under the same graphene/carbon nanotube ratio, the internal resistance of the battery is significantly reduced with the increasing amount of conductive agent, and the discharge capacity, rate performance and cycle performance are all improved. When the conductive agent is 1.5% Gen/CNT (3/7, w/w), the discharge specific capacity at 0.2 C can reach 163.2 mAh/g, and the specific discharge capacity can still reach 85.5 mAh/g at 5 C, with the best circulation performance. After 200 cycles at 1 C, the capacity retention rate can reach 103.12%.