Construction of an inverted-capacitive deionization system utilizing pseudocapacitive materials

Abstract

An inverted-capacitive deionization (i-CDI) cell of MnO2//polypyrrole-coated activated carbon (MnO2//PPy@AC) with pseudocapacitive characteristics enables unique salt-removal/salt-concentration capability. The salt adsorption capacity (SAC) of MnO2//PPy@AC highly depends on the discharging time and a high SAC of 27.6 mg·g−1 is obtained at the 60-min discharging time. The SAC retention of this unique cell is 100% after 10 charge/discharge cycles at 1.2/0 V. The “memory effect” of MnO2//PPy@AC is confirmed by the unchanged conductivity of the cell when the applied cell voltage is interrupted, which has been demonstrated for salt-removal and salt-concentration applications. Keywords: Inverted-capacitive deionization, Pseudocapacitive materials, Manganese dioxide, Polypyrrole, Memory effect