Performance of Manganese Oxide/CNTs Composites as Electrode Materials for Electrochemical Capacitors

Nanocrystalline metal oxides can be prepared with large surface area, electrochemical stability, and pseudocapacitive behavior, being able to be used as supercapacitor electrodes. Among the various metal oxides studied, amorphous and hydrated manganese oxide (a-MnO 2 .nH 2 O) is the most promising for supercapacitor electrodes due to the low cost of the raw material. In the present work, amorphous manganese dioxide (a-MnO 2 .nH 2 O) is prepared by chemical co-precipitation of Mn(VII) and Mn(II) in water medium, giving small particles of relatively high surface area. Carbon nanotubes (CNTs) are proposed as an alternative additive of carbon black for improving the electrical conductivity of the manganese oxide electrodes used to build capacitors. The results demonstrate that CNTs are effective for increasing the capacitance and improving the electrochemical properties of the a-MnO 2 .nH 2 O electrodes which show a better capacitive behavior than with carbon black. This enhancement is due to the high entanglement of CNTs which form a network of open mesopores, allowing the bulk of MnO 2 to be easily reached by the ions. The performance optimization requires a careful control of the electrolyte pH in order to avoid the irreversible reactions Mn(IV) to Mn(II) at the negative electrode and Mn(IV) to Mn(VII) at the positive one.

[1]  M. Pourbaix.  Atlas of Electrochemical Equilibria in Aqueous Solutions , 1974 .

[2]  B. Conway,et al.  Quantitative modeling of factors determining Ragone plots for batteries and electrochemical capacitors , 1996 .

[3]  B. Conway,et al.  Stages in the development of thick cobalt oxide films exhibiting reversible redox behavior and pseudocapacitance , 1999 .

[4]  Seok-Hyun Lee,et al.  Use of KCl Aqueous Electrolyte for 2 V Manganese Oxide/Activated Carbon Hybrid Capacitor , 2002 .

[5]  Bruce Dunn,et al.  Deposition of Ruthenium Nanoparticles on Carbon Aerogels for High Energy Density Supercapacitor Electrodes , 1997 .

[6]  Chi-Chang Hu,et al.  Ideal capacitive behavior of hydrous manganese oxide prepared by anodic deposition , 2002 .

[7]  James A. Ritter,et al.  Development of carbon-metal oxide supercapacitors from sol-gel derived carbon-ruthenium xerogels , 1999 .

[8]  Nae-Lih Wu,et al.  Nanocrystalline oxide supercapacitors , 2002 .

[9]  Chi-Chang Hu,et al.  The optimization of specific capacitance of amorphous manganese oxide for electrochemical supercapacitors using experimental strategies , 2003 .

[10]  B. Conway,et al.  The role and utilization of pseudocapacitance for energy storage by supercapacitors , 1997 .

[11]  Chi-Chang Hu,et al.  Capacitive and textural characteristics of hydrous manganese oxide prepared by anodic deposition , 2002 .

[12]  Jim P. Zheng,et al.  A New Charge Storage Mechanism for Electrochemical Capacitors , 1995 .

[13]  I. Kinloch,et al.  Ultra-low electrical percolation threshold in carbon-nanotube-epoxy composites , 2003 .

[14]  K. Kobayakawa,et al.  Electrochemical Behavior of Activated‐Carbon Capacitor Materials Loaded with Ruthenium Oxide , 1999 .

[15]  O. Park,et al.  Hybrid electrochemical capacitors based on polyaniline and activated carbon electrodes , 2002 .

[16]  F. Béguin,et al.  Carbon materials for the electrochemical storage of energy in capacitors , 2001 .

[17]  Jeffrey W. Long,et al.  Voltammetric Characterization of Ruthenium Oxide-Based Aerogels and Other RuO2 Solids: The Nature of Capacitance in Nanostructured Materials , 1999 .

[18]  Werner J. Blau,et al.  Experimental observation of scaling laws for alternating current and direct current conductivity in polymer-carbon nanotube composite thin films , 2002 .

[19]  P. Simon,et al.  Hybrid Supercapacitors Based on Activated Carbons and Conducting Polymers , 2001 .

[20]  P. Simon,et al.  Activated Carbon/Conducting Polymer Hybrid Supercapacitors , 2003 .

[21]  Mao-Sung Wu,et al.  Fabrication of Nanostructured Manganese Oxide Electrodes for Electrochemical Capacitors , 2004 .

[22]  B. Dunn,et al.  Morphology and Electrochemistry of Ruthenium/Carbon Aerogel Nanostructures , 1999 .

[23]  E. Kalu,et al.  Cyclic voltammetric studies of the effects of time and temperature on the capacitance of electrochemically deposited nickel hydroxide , 2001 .

[24]  John B. Goodenough,et al.  Supercapacitor Behavior with KCl Electrolyte , 1999 .

[25]  Junhua Jiang,et al.  Electrochemical supercapacitor material based on manganese oxide: preparation and characterization , 2002 .

[26]  Ralph E. White,et al.  Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors , 2001 .

[27]  S. Bonnamy,et al.  High yield of pure multiwalled carbon nanotubes from the catalytic decomposition of acetylene on in-situ formed cobalt nanoparticles. , 2002, Journal of nanoscience and nanotechnology.

[28]  Mathieu Toupin,et al.  A Hybrid Activated Carbon-Manganese Dioxide Capacitor using a Mild Aqueous Electrolyte , 2004 .

[29]  Debra R. Rolison,et al.  Structure of Hydrous Ruthenium Oxides: Implications for Charge Storage , 1999 .

[30]  S. W. Kim,et al.  Expansion of Active Site Area and Improvement of Kinetic Reversibility in Electrochemical Pseudocapacitor Electrode , 2001 .

[31]  Jim P. Zheng,et al.  Hydrous Ruthenium Oxide as an Electrode Material for Electrochemical Capacitors , 1995 .

[32]  M. Anderson,et al.  Novel Electrode Materials for Thin‐Film Ultracapacitors: Comparison of Electrochemical Properties of Sol‐Gel‐Derived and Electrodeposited Manganese Dioxide , 2000 .

[33]  F. Béguin,et al.  Supercapacitors from nanotubes/polypyrrole composites , 2001 .

[34]  Deborah J. Jones,et al.  Manganese oxide nanocomposites: preparation and some electrochemical properties , 2004 .

[35]  Milo S. P. Shaffer,et al.  Development of a dispersion process for carbon nanotubes in an epoxy matrix and the resulting electrical properties , 1999 .

[36]  O Ok Park,et al.  Carbon nanotube/RuO2 nanocomposite electrodes for supercapacitors , 2003 .

[37]  Arumugam Manthiram,et al.  Nanocrystalline Manganese Oxides for Electrochemical Capacitors with Neutral Electrolytes , 2002 .

[38]  Mathieu Toupin,et al.  Influence of Microstucture on the Charge Storage Properties of Chemically Synthesized Manganese Dioxide , 2002 .

[39]  F. Béguin,et al.  Electrochemical storage of energy in carbon nanotubes and nanostructured carbons , 2002 .

[40]  E. Frąckowiak,et al.  Capacitance properties of poly(3,4-ethylenedioxythiophene)/carbon nanotubes composites , 2004 .

[41]  A. Rao,et al.  Enhanced supercapacitance of multiwalled carbon nanotubes functionalized with ruthenium oxide , 2003 .