How the Thermal Effect Regulates Cyclic Voltammetry of Supercapacitors
Teng Zhao, Shuangliang Zhao, Shenggao Zhou, Zhenli Xu
Abstract
Cyclic voltammetry (CV) is a powerful technique for characterizing the electrochemical properties of electrochemical devices. During charging–discharging cycles, the thermal effect can have a profound effect on its performance. However, existing theoretical models cannot clarify such an intrinsic mechanism and often give poor predictions. Herein, we propose an interfacial model for the electro-thermal coupling based on fundamentals in nonequilibrium statistical mechanics. By incorporation of molecular interactions, our model shows a quantitative agreement with experimental measurements. The integral capacitance shows a first enhanced and then decayed trend against the applied heat bath temperature. Such a relation is attributed to the competition between electrical attraction and Born repulsion via dielectric inhomogeneity, which was not well understood in previous models. In addition, as evidenced in recent experimental CV tests, our model predicts the nonmonotonic dependence of the capacitance on the bulk electrolyte density. This work demonstrates a potential pathway toward next-generation thermal regulation of electrochemical devices.