Experimental analysis of influence of different charge-discharge modes on lithium storage performance of reduced graphene oxide electrodes

Abstract

In this paper we conduct comprehensive experimental research and analyze the effect of charge-discharge modes on the performance of lithium storage. Four charge-discharge modes are designed, and the lithium storage performance experiments of the reduced graphene oxide electrode under different charge-discharge modes are carried out to analyze the effect mechanism of charge-discharge mode on lithium storage time and capacity from two aspects of electrode dynamic reaction performance and strain. The experimental results show that the shorter the lithium storage time of the electrode, the more the capacity loss under different charge-discharge modes. Comprehensive data analysis indicates that the charge transfer resistance, diffusion coefficient, overpotential and strain in the electrochemical process show non-linear and staged characteristics, resulting in the different lithium storage performances’ mechanism of different stages under different charge-discharge modes. Finally, “High current-low current” mode is proposed as a feasible optimization plan for charging and discharging. In the initial stage-I, the dual role of large electric field drive and concentration gradient drive enhances the migration and diffusion rate and shortens the lithium storage time; in the stage-II, the small current relieves local concentration accumulation and increases the amount of lithium inserted, thereby giving full play to the greatest advantage of current in each stage and balance the discrepancy between time and capacity. And this discussion provides certain guidance for designing and optimizing the fast charging technology.