Synthesis of Birnessite-Type Layered Manganese Oxide and their Composites for Supercapacitors

Abstract

Birnessite-type layered manganese oxides were prepared using various approaches for the design and fabrication of supercapacitor electrodes: (i) Oxidized carbon-MnO2 nanocomposites were obtained from birnessite precipitated in the presence of the oxidized forms of four different carbon types: graphite, acetylene black, high surface area active carbon and fullerene. (ii) films were anodically deposited at the surface of inexpensive stainless steel foils. MnSO4 plating solutions were electrolyzed at various potentials and for various durations. Preparation conditions are shown to affect the oxide structure, morphology (surface area), and chemical composition (content of Mn3+, Mn4+). Consequently, they also greatly affect the electrochemical capacitance performances of the prepared electrode materials.

Synergy of Mn and Co in Slab-Based Nanocomposites for Hybrid Supercapacitors: Impact of Restacking Process on Electrochemical Properties

“…Pristine β3-CoOOH reveals a very low capacitance while pristine H-MnO 2 exhibits a high pseudocapacitance, as already reported. 69,70 In both cases, the specific capacitances obtained for exfoliated/restacked materials are systematically higher than their initial parents. This trend can be attributed to a different structuration of nanosheets induced by exfoliation, resulting in an increase of the active electrochemical surface in contact with the electrolyte.…”