title: Hierarchically porous carbon with manganese oxides as highly efficient electrode for asymmetric supercapacitors.
abstract: A promising energy storage material, MnO2 /hierarchically porous carbon (HPC) nanocomposites, with exceptional electrochemical performance and ultrahigh energy density was developed for asymmetric supercapacitor applications. The microstructures of MnO2 /HPC nanocomposites were characterized by transmission electron microscopy, scanning transmission electron microscopy, and electron dispersive X-ray elemental mapping analysis. The 3-5 nm MnO2 nanocrystals at mass loadings of 7.3-10.8 wt % are homogeneously distributed onto the HPCs, and the utilization efficiency of MnO2 on specific capacitance can be enhanced to 94-96 %. By combining the ultrahigh utilization efficiency of MnO2 and the conductive and ion-transport advantages of HPCs, MnO2 /HPC electrodes can achieve higher specific capacitance values (196 F g(-1) ) than those of pure carbon electrodes (60.8 F g(-1) ), and maintain their superior rate capability in neutral electrolyte solutions. The asymmetric supercapacitor consisting of a MnO2 /HPC cathode and a HPC anode shows an excellent performance with energy and power densities of 15.3 Wh kg(-1) and 19.8 kW kg(-1) , respectively, at a cell voltage of 2 V. Results obtained herein demonstrate the excellence of MnO2 /HPC nanocomposites as energy storage material and open an avenue to fabricate the next generation supercapacitors with both high power and energy densities.
authors: Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013 (Taiwan).
authors: Tsu-Chin
authors: TC
authors: Chou
authors: Ruey-An
authors: RA
authors: Doong
authors: Chi-Chang
authors: CC
authors: Hu
authors: Bingsen
authors: B
authors: Zhang
authors: Dang Sheng
authors: DS
authors: Su
mesh_terms: D002244:Carbon / Q000737:chemistry*; D025802:Electric Capacitance; D004563:Electrochemistry; D004566:Electrodes; D017895:Manganese Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D016062:Porosity
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C027424:manganese oxide; D002244:Carbon
keywords: cyclic voltammetry; electrochemistry; electron microscopy; materials science; nanostructures