Hydrous RuO[sub 2]/Carbon Black Nanocomposites with 3D Porous Structure by Novel Incipient Wetness Method for Supercapacitors

Abstract

For supercapacitor electrode material, hydrous RuO 2 /carbon black nanocomposites were prepared by the novel incipient wetness method using a fumed silica nanoparticle. First, hydrous RuO 2 /fumed silica/Ketjen black ͑KB͒ was synthesized by the sol-gelbased method. After dissolving the fumed silica, the hydrous RuO 2 /KB nanocomposite, which is composed of RuO 2 nanoparticles ͑20-60 nm͒ dispersed on the high-surface-area KB ͑1180 m 2 g −1 ͒, was formed with 3D porous structure at high loading of 60 wt % RuO 2 ͑Ru content is 46 wt %͒. The hydrous RuO 2 /KB nanocomposite electrode exhibited a specific capacitance of 647 F g −1 with high charge utilization of RuO 2 ͑72%͒, which is significantly higher than reported values by other workers at similar loading of RuO 2 . The high capacitance and the high charge utilization were probably due to enhanced proton paths within the 3D porous structure of the nanocomposite materials.

Advanced asymmetrical supercapacitors based on graphene hybrid materials

“…The specific capacitance values of our RuO 2 /graphene hybrid are highly competitive with other RuO 2 materials measured in alkaline electrolytes [26][27][28]. Although higher capacitances have been measured for RuO 2 in acidic electrolytes [21,[29][30][31][32][33], alkaline electrolytes are required by the Ni(OH) 2 /graphene hybrid, which is the counter electrode of RuO2/graphene in the asymmetrical supercapacitor as shown below.…”

“…This differs from the symmetrical RuO 2 /graphene device in which the voltage drop is evenly divided by the two electrodes at any point of time during charge-discharge. RuO 2 has been shown to be a promising high energy density supercapacitor material, with the caveat of high cost [21,[26][27][28][29][30][31][32][33]. Compared to RuO 2 based supercapacitors reported previously [21,[27][28][29][30][31][32][33], including a RuO 2 /graphene-RuO 2 /graphene pair [21] and a RuO 2 -RuO 2 pair [31], our asymmetrical Ni(OH) 2 /graphene and RuO 2 /graphene supercapacitor shows higher electrochemical performance, especially in terms of higher energy densities (Fig.…”

Supercapacitive properties of composite electrodes consisting of polyaniline, carbon nanotube, and RuO2

“…Due to the inherently dense morphology of the RuO 2 , however, only a very thin surface layer of this material participated in the charge storage process, and the underlying bulk material remained as dead volume, resulting in a reduction in specific capacitance. Many attempts to overcome these drawbacks have been made by synthesizing composites of RuO 2 with activated carbon [15][16][17], CNTs [18][19][20][21], carbon nanofibers [22], and some conducting polymers [23,24]. For instance, RuO 2 / 90% activated carbon and RuO 2 /CNT composites recently achieved very high capacitance values over 1,000 F g -1 [15,19,20].…”

A comparison study of the capacitive behavior for sol–gel-derived and co-annealed ruthenium–tin oxide composites

“…However, very high specific capacitance, 720 F g −1 , was first obtained at a very low scan rate (i.e., 2 mV s −1 ) from the sol-gel-derived RuO 2 ·xH 2 O through a careful control of the annealing process [25]. After this finding, RuO 2 ·xH 2 O was reported to synthesize through various methods, including potentiodynamic deposition [13], electrostatic spray deposition [26], chemical precipitation of RuO 2 ·xH 2 O colloids [27], solid-state reaction of K 2 CO 3 and RuO 2 [28], oxidative synthesis [19], hydrothermal synthesis [29], and incipient wetness method [30], etc. The above studies tried to develop simple, effective methods for synthesizing amorphous or crystalline RuO 2 or a better utilization of RuO 2 ·xH 2 O for this application.…”