接触电阻对电化学阻抗影响的试验研究

Experimental Study on the Impact of Contact Resistance on Electrochemical Impedance

在电化学阻抗测试中,电极作为传递信号的载体,电极与材料的接触程度,也即之间存在的接触电阻的大小,直接影响到了电化学阻抗及其阻抗谱所拟合等效电路参数的结果。通过对粉土、灰土分别在不同电极间压力和不同电极面积的正交试验下,所测得的阻抗|Z|和接触电阻R_0,来探求R_0与|Z|及其等效电路参数的关系。研究表明:电化学阻抗谱呈现非Randles模型的材料,可以提出类似于材料电阻率ρ_m的材料阻抗率ρ来表征材料的特性;同时ρ可以用其相对应的R_0与参数α的乘积表示。α随着电极间压力的增大而缓慢增大,随着电极面积的增大而急剧增大,随着材料压缩模量E_s的增大而减小;随着电极间压力的增大,其ρ、R_0、|Z|以及等效电路参数溶液电阻R_s、电荷转移电阻R_t在不断减小,而其双电层电容C_d在不断增大;随着电极面积的增大,其R_0、C_d在不断减小,而其ρ、|Z|、R_s和R_t在不断增大;随着材料E_s、ρ_m的增大,其ρ、R_0、R_s和R_t在不断增大,而其C_d不断减小。

In electrochemical impedance test,electrode as a signal of the carrier,the contact extent between electrode and material,that the size of the contact resistance between electrode and material,directly affects the results of electrochemical impedance and its equivalent circuit parameters that its impedance spectrum by fitting. By means of orthogonal test in different electrode pressure and under different electrode area for powder soil and limesoil,it measured impedance ｜ Z ｜ and contact resistance R0,to explore the relationship between R0 with ｜ Z ｜ and its equivalent circuit parameters. Research shows that： the material that its electrochemical impedance spectroscopy to present the un-Randles model,can propose the impedance ratio ρ that is similar to materials resistivity ρm,to represent materials characterize,at the time,ρ can use the product between of its corresponding to R0 and parameter α to present,α and slow increase with the increase of pressure between electrodes,and a sharp increase with the increase of electrode area and decreases with the increase of material compression modulus Es; with the increase of pressure between electrodes,its ρ,R0,｜ Z ｜,equivalent circuit parameter solution resistance Rs and the charge transfer resistance Rtis reduced,but its electric double layer capacitor Cd in increasing; with the increase of electrode area,its R0,Cd is reduced,and the ρ,｜ Z ｜,Rs,Rt in increasing; with the decrease of the material modulus of deformation,with the increase of Es and ρm,its ρ,R0,Rs and Rt in increasing,but the Cd and decreases.