Pseudocapacitive\nCoating for Effective Capacitive Deionization

Abstract

Capacitive deionization (CDI) features\na low-cost and energy-efficient desalination approach based on electrosorption\nof saline ions. To enhance the salt electrosorption capacity of CDI\nelectrodes, we coat ion-selective pseudocapacitive layers (MnO₂ and Ag) onto porous carbon electrodes (activated carbon cloth)\nwith only minimal use of a conductive additive and a polymer binder\n(<1 wt % in total). Optimized pseudocapacitive electrodes result\nin excellent single-electrode specific capacitance (>300 F/g) and\ngreat cell stability (70% retention after 500 cycles). A CDI cell\nout of these pseudocapacitive electrodes yields as high charge efficiency\nas 83% and a remarkable salt adsorption capacity up to 17.8 mg/g.\nOur finding of outstanding CDI performance of the pseudocapacitive\nelectrodes with no use of costly ion-exchange membranes highlights\nthe significant role of a pseudocapacitive layer in the electrosorption\nprocess.