Abstract
The charges stored within the pseudocapacitive materials are strongly affected by the charge-discharge rate because of their electrochemical reversibility, especially when employing a battery-type material in the asymmetric design. As a result, the charges stored in the positive and negative electrodes in asymmetric supercapacitors (ASCs) are usually not well balanced because of the wide-rate operation of ASCs. This work demonstrates how to construct an ASC with one electrode material of the battery type through the charge balance consideration using the nickel hydroxide//activated carbon (Ni(OH) 2 //AC) system as an example. Due to the fact that the electrochemical reversibility of Ni(OH) 2 is worse than that of AC, the influences of the current density (at 0.5 and 80 A g -1 ) in evaluating the charge capacity of Ni(OH) 2 on the cell capacitance, power ability, and stability of the ASC are investigated. The above parameters of this ASC are evaluated by cyclic voltammetric, constant current charge-discharge, and electrochemical impedance spectroscopic analyses. The proposed charge capacity has been demonstrated to be an important factor for determining the specific energy, power ability, and stability of ASCs. A general strategy for achieving the optimal performances of an ASC with one battery-type electrode is proposed in this work.