LiMn_2O_4中锂离子扩散系数与充/放电次数的关系

Dependence of Li+ Diffusion Coefficients in LiMn_2O_4 on Charge/Discharge Cycles

通过容量间歇滴定技术(CITT)对不同电压、不同循环次数下,锂离子在尖晶石LiMn_2O_4中的固相扩散系数进行了研究.结果表明,锂离子在尖晶石LiMn_2O_4正极材料中的固相扩散系数在3.95V和4.12V左右存在两个极小峰,随着循环次数的增加,这两个峰逐渐平坦,并且整体上固相扩散系数呈增大趋势,表明锂离子在LiMn_2O_4中重复脱/嵌时具有自我增强扩散的能力.

The solid diffusion coefficient of lithium-ion in spinel LiMn2O4 cathode material has been investigated by the capacity intermittent titration technique （CITT） at different voltages and at different charge/discharge cycles. Results show that there are two minimum peaks in the curves of the solid diffusion coefficient （D） vs voltage （E） at 3.95 V and 4.12 V in the voltage range from 3.85 V to 4.30 V. The curves of lgD-E for the first 20 cycles show that the two minimum peaks are gradually flatted out and the values of solid diffusion coefficient tend to increase when the cycling number increases. The results suggest that LiMn2O4 cathode material has the ability of selfdiffusionenhance during intercalation/deintercalation of lithium-ion.