Micelle‐Assisted Electrodeposition of <i>γ</i>‐MnO<sub>2</sub> on Lead Anodes: Structural and Electrochemical Insights
Manickam Minakshi, Rob Aughterson, Parul Sharma, Anurag Prakash Sunda, Katsuhiko Ariga, Lok Kumar Shrestha
Abstract
Electrolysis of MnSO 4 in H 2 SO 4 with cationic surfactants (tetradecyltrimethylammonium bromide; TTAB and cetyltrimethylammonium bromide; CTAB) led to the formation of γ ‐MnO 2 with surfactant intercalation in an amorphous matrix. Unlike conventional self‐standing EMD electrodes, which limit scalability, this study presents bulk electrodeposition of EMD powder on a lead (Pb) anode. Surface morphology is significantly altered by surfactant presence, though X‐ray diffraction and density functional theory analyzes confirms consistent γ ‐MnO 2 crystallography across samples. Galvanostatic charge–discharge at 0.6 A g −1 reveals that TTAB‐assisted EMD achieved a specific capacitance of 478.6 F g −1 , double that of pristine EMD (232 F g −1 ), due to improved ion transport and surface area. In contrast, CTAB‐assisted EMD shows reduced capacitance (124.6 F g −1 ), attributed to early micelle formation and immobilization within the MnO 2 lattice, which promoted SO 4 2 − insertion over surfactant deintercalation. Surfactant critical micelle concentrations and surface activity are key to electrochemical behavior in 1 M Na 2 SO 4 . An asymmetric device using TTAB‐EMD as the cathode and activated carbon as the anode delivered 106 F g −1 and 40 Wh kg −1 , demonstrating practical viability. Band structure calculations support the experimental findings, indicating favorable electronic properties for charge storage.