锂离子嵌入塑料化碳电极的交流阻抗研究

Study on AC impedance measurement of plasticized carbon electrodes with intercalation of lithium ions

研究了塑料化碳电极交流阻抗谱的基本形状,交流阻抗谱随循环伏安次数的变化,交流阻抗谱随电位的变化。描述了塑料化碳电极的等效电路,并利用等效电路拟合了不同电位下的交流阻抗谱。实验结果表明,塑料化碳电极的SEI膜主要在首次循环伏安过程中形成,但在其后的循环伏安过程中仍有增长。经过4次循环伏安后的充电过程中,随着电位的降低,SEI膜仍有增长,接触电阻下降,电荷传递反应阻抗降低,并在60mV以下观察到SEI膜阻抗的快速增长。

The basic shape of the AC (alternating current) impedance spectra of plasticized carbon electrode was described. The change of AC impedance spectra with different cycle number of cyclic voltammetry and potential were studied. The equivalent circuit of the plasticized carbon electrode was proposed, and AC impedance spectra of different potentials were fitted with equivalent circuit. According to experimental and numerical analysis results, solid electrolyte interface(SEI) is mainly formed during the first cycle of cyclic voltammetry, but the growth of SEI does not cease during the following cycles. In the following charging process, with the decline of potential, SEI still grew slowly, contact impedance and charge transfer reaction impedance declined, below 60 mV the impedance of SEI increased rapidly.