层状锂钴镍锰氧化物交流阻抗谱的研究

Electrochemical Impedance Spectroscopy of Layer Lithium Cobalt Nickel Manganese Oxide

用交流阻抗法研究了锂离子电池结构、充电状态以及温度对层状锂钴镍锰氧化物反应动力学的影响．结果表明:与未卷绕的2032电池相比,卷绕的18650电池在高频出现了感抗．根据不同电位下的阻抗谱可以推断层状锂钴镍锰氧化物的脱锂过程分为三个阶段,2．0-2．7V为克服晶格结构作用力阶段,2．7-3．65V为锂离子多层钝化膜的形成过程,3．65-4．25V为多层钝化膜与溶液界面的双电层形成过程．温度的升高加快了电荷传递速度和锂离子扩散速度,计算得到电荷传递活化能和锂离子扩散活化能分别为20．48、48.67kJ／mol,且后者是电化学反应的控制步骤．

Electrochemical impedance spectroscopy （EIS） was applied to study the reaction kinetics of layer lithium cobalt nickel manganese oxide material. Effects of the battery structure, charge depth and temperature on the layer lithium cobalt nickel manganese oxide cathode electrodes were tested by EIS. The results show that the inductance appears in the 18650 winding cells while not in 2032 cells. The whole process consists of overcoming strcture force period of oxygen layers crystal lattice in the rang of 2.0-2.7V, lithium-ion membranes forming period in the range of 2.7--3.65V and interface electrical double layer forming period in the range of 3.65-4.25V.The charge transfer rate and Li-ion diffuse rate are improved with temperature increasing. The charge transfer and lithium ion diffusion activation energies are 20.48kJ/mol and 48.67k J/tool respectively, so the lithium ion diffusion process is the control process of the whole electrochemical reaction.