不同充放电模式影响还原氧化石墨烯电极储锂性能的实验分析

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

针对充放电模式对电极储锂性能的影响开展综合实验研究与机理分析.设计了4种充放电模式,进行不同充放电模式下还原氧化石墨烯电极的储锂性能实验,并从电极动态反应性能和应变两方面开展实验分析充放电模式对储锂时间和容量的影响机理.实验结果显示,不同充放电模式下电极储锂时间越短容量折损越多,综合数据分析指出电荷转移阻抗、扩散系数、过电位和应变均表现出了非线性和阶段性的特点.最后提出“大电流-小电流”模式为可行的充放电优化方案,利用电化学进程的非线性平衡了快充技术中时间和容量之间的矛盾,为快速充电技术的设计和优化提供了一定的指导.

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.