库仑法和电化学阻抗法测量LiFePO_4锂离子扩散系数

Determination of Li-ion Diffusion Coefficient via Coulometric Titration and Electrochemical Impendence Method

库仑法和电化学阻抗法是测量锂离子扩散系数有效的测量手段。以实验室自制的LiFePO4为实验电池正极材料,介绍如何用库仑法和阻抗法测试并计算电极材料的锂离子扩散系数。库仑法计算得到锂离子扩散系数由Li1-xFePO4(x=0)的9.6×10-9cm2.s-1变化为Li1-xFePO4(x=0.7)的1.1×10-11cm2.s-1。用阻抗法的两种模型,分别计算了Li1-xFePO4(x=0.65)的电池材料的锂离子扩散系数,结果分别是8.5×10-11cm2.s-1和3.1×10-12cm2.s-1。三种方法的计算结果接近。

Li-ion diffusion coefficient can be effectively obtained from coulometric titration and electrochemical impendance method. The paper takes self-made LiFePO4 as an example to calculate the Li-ion diffusion coefficient by using coulometric titration and electrochemical impendence method. The results of coulometric titration shows that it varies from 9.6 x 10-gcm2·s-1 to 1.1 × 10-11 cm2 ·s-1 as a function of x in Li1-xFePO4 when xequals 0 to 0. 7. Based on two different models of electrochemical impendance spectroscopy, the paper calculates the Li-ion diffusion coefficient of Li1-xFePO4 （x = 0. 65 ） and the results are 8.5 x 10-11 cm2·s-1 and 3.1×l0-12cm2·s-1 respectively. Three results are in good agreement.