尖晶石锂锰氧化物锂离子嵌脱过程的交流阻抗谱研究

Study on Electrochemical Impedance Spectroscopies of Insertion and Deinsertion of Lithium Ion in Spinel Lithium Manganese Oxide

用粉末微电极研究了尖晶石锂锰氧化物在不同嵌锂状态下嵌脱锂过程的交流阻抗图谱 ,提出了新的等效电路模型 .描述锂离子在固体中扩散的Warburg阻抗与累积或消耗的嵌入电容在LixMnO4中的x≤ 0 .5时串联 ,0 .5 <x≤ 1时并联 .用提出的等效电路模型分阶段拟合了实验所得的交流阻抗谱 ,拟合值与实验值相当吻合 ,由拟合结果得到不同电位下锂离子在表面膜中的迁移电阻和电容 ,界面电荷传递电阻 ,双层电容 。

Electrochemical impedance spectroscopies of insertion and deinsertion of U ion in spinel lithium manganese oxide with different contents of inserted lithium ions were studied by using a powder microelectrode. New equivalent circuits modeling the insertion and deinsertion were proposed to fit the experimental electrochemical impedance spectroscopies. The Warburg impedance describing the diffusion and the insertion capacitance describing the accumulation or consumption of U ion in the oxide are in sequence when x less than or equal to 0.5, but in paralell when 0.5 < x 1 in Li-x MnO4. The fitting results were in agreement with the experimental results. The capacitance and the resistance for the transfer of Li ions in the surface film on the oxide, the double capacitance and the resistance for the charge transfer of Li ion insertion or deinsertion, and the Warburg impedance and the insertion capacitance under different potentials were obtained by using the proposed models.