Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices

A facile and low-cost method has been employed to fabricate MnO₂/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO₂ nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO₂ nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO₂ content and crystallite size via the concentration of KMnO₄ used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g^-1 in electrodes containing 3 wt % MnO₂ with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.