Preparation of MnO2 and Composites for Ultracapacitors

New dispersants were investigated for the preparation of MnO2 and composites by electrophoretic deposition (ED). The investigation of molecules from salicylate, phenolate, catecholate, and phthalate families allowed the comparison of different mechanisms, which provided dispersant bonding to the MnO2. The deposition yield was studied at various experimental conditions. Catecholate bonding resulted in significantly higher colloidal stability and deposition rate, compared to salicylate bonding. It was shown that agglomeration of MnO2 nanoparticles can be avoided when MnO2 synthesis is performed in the presence of dispersants. MnO2-multiwalled carbon nanotubes (MWCNT) composites for ultracapacitors were obtained by ED. The use of Ni plaque current collectors allowed high capacitance and low electrochemical impedance at higher material loadings, compared to stainless steel foil current collectors. The electrodes showed a capacitance of 185 Fg−1. The MnO2–MWCNT electrodes can be used for applications in ultracapacitors.