Electrochemical Characteristics of Cobaltosic Oxide in Organic Electrolyte According to Bode Plots: Double‐Layer Capacitance and Pseudocapacitance

Abstract Pseudocapacitive behavior is usually observed in transition‐metal oxide anodes for lithium‐ion batteries, such as Co 3 O 4 . It is necessary to develop electrochemical technologies for clarifying the properties of the pseudocapacitance in the electrode reactions, as the understanding and controllable application of pseudocapacitance benefits the development of electrode materials with multi‐storage mechanisms for lithium‐ion batteries. To this end, in this work, electrode processes are divided into four component parts with corresponding equivalent circuit diagrams used to emphasize the pseudocapacitive behavior of Co 3 O 4 . After analyzing the properties of Bode plots in the whole frequency range (10 −2 –10 5 Hz), phase‐angle Bode plots are demonstrated to be suitable for revealing the pseudocapacitance for Co 3 O 4 at a certain state. In addition, is utilized to determine the magnitude of the pseudocapacitance and double‐layer capacitance. For Co 3 O 4 in the fully charged state (3 V vs. Li + /Li), the pseudocapacitance and double‐layer capacitance are approximately 180.28 and 1.32 μF cm −2 , respectively. Therefore, the goal of monitoring pseudocapacitive behavior for a transition‐metal oxide anode such as Co 3 O 4 in a certain state without the influence of double‐layer capacitance and faradaic processes controlled by solid‐phase diffusion is realized by using Bode plots, greatly promoting the understanding and controllable application of pseudocapacitance.