双电层电容器电化学阻抗谱的实验研究(英文)

电化学阻抗谱(EIS)是一种很有用的研究电化学性能的技术.理想的双电层电容器(EDLC)阻抗谱的尼奎斯特图由中高频的45°线和低频的与实轴垂直的直线组成,可以用孔径分布-传输线模型来解释.然而,在研究工作中还发现,在阻抗谱的高频区出现了半圆弧区域,为此,提出的等效模型认为半圆弧可以归因于活性材料之间的接触电阻和接触电容,以及电极与集流体之间的接触电阻与接触电容.还研究了充电过程、活性炭和电解液的电导率、导电添加剂和粘结剂的含量、隔膜、活性物质附载量和极片加压等因素对阻抗谱的影响.其中,充电截止电压、活性炭的电导率、导电添加剂的含量和极片加压对半圆弧部分影响较为显著.

Experimental Investigation of Electrochemical Impedance Spectroscopy of Electrical Double Layer Capacitor

Electrochemical impedance spectroscopy (EIS) is a very useful technique for studying electrochemical behavior. The ideal Nyquist plot of electrochemical impedance spectroscopy for an electrical double-layer capacitor (EDLC) consists of a 45° line in the high-middle frequency region and a vertical line in the low frequency region, which can be explained by the transmission line model with pore size distribution. However, a semicircle loop in the high frequency region has been found in many studies. Hence, in this study, an equivalent model is proposed, in which the semicircle loop is ascribed to the contact resistance and contact capacitance between particles of activate materials, and between the activated carbon (AC) electrode and current collector. The effects of the charging process, conductivities of the active material and electrolyte, content of conductive additive and binder, porous separator, mass loading, and exerted pressure to the electrode on the EIS spectra of EDLCs were experimentally investigated. Among these effects, the most significant factors were the charging cut-off voltage, conductivity of activated carbon, content of conductive additive, and exerted pressure.