Electrochemical capacitors of RuO2 nanophase grown on LiNbO3(100) and sapphire(0001) substrates

The electrochemical properties of RuO2/LNO and RuO2/SA electrodes made of RuO2 rods and plates of nanometre size on LiNbO3(100) and sapphire(0001) substrates are investigated. Both rods and plates are grown vertically using chemical vapor deposition. The RuO2/LNO electrode has a higher electrolyte/solid surface area compared with the RuO2/SA electrode. When immersed in H2SO4 acid, voltammograms of both electrodes exhibit chemisorption and pseudocapacitive characteristics of the RuO2 single crystal. The chemisorption features decrease after repeated cyclic voltammetry (CV) sweeps, and the voltammograms become more mirror-like. The specific capacitance of the RuO2/LNO electrode measured in CV is 569 F g−1, that of RuO2/SA 357 F g−1. These values are reconfirmed in charging–discharging measurements. The measured capacitance decreases with the sweep rate, and the decreasing trend of RuO2/LNO is higher than that of RuO2/SA. Reduction of accessible charge at high sweep rates results from higher internal resistance of the RuO2/LNO electrode which is distributed because of its porous nature. The impedance spectrum of the RuO2/LNO electrode confirms its higher internal resistance. It also indicates the electrode is a nearly ideal capacitor below a knee frequency 200 Hz. Since the knee frequency is less than 1 Hz for most electrochemical capacitors, both RuO2/LNO and RuO2/SA are electrodes for fast charging–discharging applications.

[1]  P. Lu,et al.  Epitaxial growth of RuO2 thin films by metal-organic chemical vapor deposition , 1999 .

[2]  A. Battisti,et al.  Examination of RuO2 single-crystal surfaces: charge storage mechanism in H2SO4 aqueous solution , 2002 .

[3]  C. C. Chen,et al.  The growth and characterization of well aligned RuO2 nanorods on sapphire substrates , 2004 .

[4]  Nae-Lih Wu,et al.  Composite Supercapacitor Containing Tin Oxide and Electroplated Ruthenium Oxide , 2003 .

[5]  Yao-Lun Chen,et al.  Preparation and characterization of RuO2 thin films from Ru(CO)2(tmhd)2 by metalorganic chemical vapor deposition , 2002 .

[6]  W. O'grady,et al.  Effect of Crystallographic Orientation of Single‐Crystal RuO2 Electrodes on the Hydrogen Adsorption Reactions , 1984 .

[7]  Jim P. Zheng,et al.  Characterization of RuO 2 xH 2O with various water contents , 2002 .

[8]  R. Hoch,et al.  High power electrochemical capacitors based on carbon nanotube electrodes , 1997 .

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

[10]  Young Soo Yoon,et al.  Thin Film Supercapacitors Using a Sputtered RuO2 Electrode , 2001 .

[11]  D. Tsai,et al.  Area-selective growth of ruthenium dioxide nanorods on LiNbO3(100) and Zn/Si substrates , 2004 .

[12]  C. Lokhande,et al.  Electrodeposited ruthenium oxide (RuO2) films for electrochemical supercapacitors , 2004 .

[13]  G. Battaglin,et al.  Microstructural characterization and electrochemical properties of RuO2 thin film electrodes prepared by reactive radio-frequency magnetron sputtering , 2004 .

[14]  S. Trasatti,et al.  Ruthenium dioxide: A new interesting electrode material. Solid state structure and electrochemical behaviour , 1971 .

[15]  Wendy G. Pell,et al.  Power limitations of supercapacitor operation associated with resistance and capacitance distribution in porous electrode devices , 2002 .

[16]  Chi-Chang Hu,et al.  How to Achieve Maximum Utilization of Hydrous Ruthenium Oxide for Supercapacitors , 2004 .

[17]  A. Lewandowski.  Electrochemical capacitors with polymer electrolytes based on ionic liquids , 2003 .

[18]  Wendy G. Pell,et al.  Voltammetry at a de Levie brush electrode as a model for electrochemical supercapacitor behaviour , 2001 .

[19]  Il-Hwan Kim,et al.  Ruthenium Oxide Thin Film Electrodes for Supercapacitors , 2001 .

[20]  M. Eizenberg,et al.  Chemical Vapor Deposited RuO x Films Effect of Oxygen Flow Rate , 2002 .

[21]  W. Yonggang,et al.  Preparation and electrochemical capacitance of RuO2/TiO2 nanotubes composites , 2004 .

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

[23]  D. F. Evans,et al.  Microstructure of ruthenium dioxide films grown on α–Al_2O3 (0001), α–Al_2O_3 ( $$1\overline 1 02$$ ), and SrTiO_3 (100) using reactive sputtering , 1997 .

[24]  D. Scherson,et al.  In Situ Ru K-Edge X-Ray Absorption Fine Structure Studies of Electroprecipitated Ruthenium Dioxide Films with Relevance to Supercapacitor Applications , 2000 .

[25]  H. L. Park,et al.  Cyclic voltammetry on RuO2 (100), (101), (001) and (110) “as-grown” single-crystal surfaces , 1983 .

[26]  S. Milonjić,et al.  The properties of carbon-supported hydrous ruthenium oxide obtained from RuOxHy sol , 2003 .