How to Achieve Maximum Utilization of Hydrous Ruthenium Oxide for Supercapacitors

Abstract

The utilization of hydrous ruthenium oxide ͑denoted as RuO x •nH 2 O) was promoted by annealing the oxide in air as well as by mixing it with conductive activated carbon ͑AC͒ due to the significant improvement in intra-and interparticle electronic conductivity, respectively. The maximum specific capacitance (C S,RuOx ) of RuO x •nH 2 O, 1340 F/g ͑measured at 25 mV/s͒, very close to the theoretic value, was obtained from a composite consisting of AC and RuO x •nH 2 O coated on graphite ͑denoted as AC-RuO x /G) with 10 wt % of sol-gel-derived RuO x •nH 2 O nanodots annealed in air at 200°C for 2 h. The UV absorption spectral features showed a shift in max to the red as the mean particle size of RuO x •nH 2 O nanodots was increased, attributable to the surface plasmon resonance phenomenon. The average particle size of highly uniform RuO x •nH 2 O nanodots, ranged from 2.05 to 3.01 nm, was estimated from the high-resolution transmission electron microscopy. The dependence of capacitive performance on the size and content of RuO x •nH 2 O nanodots, evidenced by cyclic voltammetry and electrical impedance spectroscopy results, revealed the important influences of interparticle electronic conductivities on the utilization of RuO x •nH 2 O. The RuO x •nH 2 O nanodots with and without annealing in air at 200°C for 2 h showed the amorphous structure from both the X-ray diffraction and electron diffraction analysis.

Preparation and characterization of RuO2/polyaniline/polymer binder composite electrodes for supercapacitor application

“…Cyclic voltammograms of the composite electrodes with PVDF ( Figure 2, black lines) as a binder show very broad anodic peak at about 0.5 V, which is commonly observed in the cyclic voltammograms of hydrous RuO 2 ·xH 2 O [6][7][8]25]. It is usually explained by the reversible processes which accompany the sorption of protons and water molecules [38,39].…”

“…It is now well established and confirmed by several authors that, in order to achieve the maximal utilization of ruthenium oxide and extract as much charge as possible, two parameters, electronic and protonic conductivity, should be optimized. This is usually done by annealing the amorphous RuO 2 ·xH 2 O at appropriate temperatures [5][6][7][8][9][10][11][12][13].…”

“…One strategy includes the different RuO 2 preparation methods [4,[8][9][10][11][14][15][16][17][18][19][20][21][22][23], whereas several authors recognized the importance of both intra-and inter-particle electronic conductivities and prepared the composite materials of RuO 2 with various forms of carbon [6,18,19,[27][28]. It was observed that nano-structured RuO 2 particles were decisive factor in achieving the high gravimetric capacitance [29,30].…”

“…It was observed that nano-structured RuO 2 particles were decisive factor in achieving the high gravimetric capacitance [29,30]. Carefully prepared electrodes with low RuO 2 loadings and good electric contact between RuO 2 and underlying conductive support gravimetric capacitances of RuO 2 as high as 1500 F/g and even higher can be achieved [6,7,13].…”

Facile Low-temperature Chemical Synthesis and Characterization of a Manganese Oxide/multi-walled Carbon Nanotube Composite for Supercapacitor Applications

“…8 However, despite the superior performance of ruthenium oxide, it is still limited in its industrial supercapacitor applications due to its high cost. 9 Hence, considerable effort is being devoted to developing inexpensive metal oxide electrode materials with excellent supercapacitive performance.…”