Electrodeposited MnO2 For Pseudocapacitive Deionization: Relating Deposition Condition and Electrode Structure to Performance

Abstract

Electrodeposited MnO2 was screened as a possible pseudocapacitive material for use in a capacitive deionization (CDI) environment. Two simple electrochemical deposition conditions (galvanostatic and cyclic voltammetric) were used to produce MnO2 coatings on porous carbon substrates with contrasting surface areas and morphologies. These samples were then tested in static half-cell test fixtures with the intention of probing how these types of substrates and coatings might work in a CDI flow cell. The results show that the best sodium ion uptake performance on per-mass basis was not necessarily the most compelling electrode-level solution for practical application, and that a high surface area nanoporous substrate displayed evidence of a self-limited deposition wherein the internal electrode volume was not able to participate in the ion removal reactions of interest.