Direct Growth Of Vertically Aligned Carbon Nanotube (VACNT) On Different Conducting Substrates For Electrochemical Capacitor (EC)

Electrochemical capacitor (EC) is highly promising energy device due to its electrical charge storage performance and significant lifecycle ability. Construction of the EC cell especially its electrode fabrication is critical to ensure great application performance. The purpose of this research is to introduce direct growth of vertically aligned carbon nanotube (VACNT) on conducting substrates, namely SUS 310S, Inconel 600, and YEF 50 and their usage as symmetric VACNT electrode in EC. The substrates were deposited by alumina and cobalt catalyst thin films, and then the growth was done by using alcohol catalytic chemical vapour deposition. By this, VACNT was successfully grown and their structures (dimension, walls)have been confirmed by means of electron microscopies. The thickness of the VACNT is typically about 31.68 μm (SUS 310S) and 10.58 μm (Inconel 600), respectively which indicate that no particular agglomerated metals were observed on the exposed surface of the substrate.In contrast, the field emission scanning electron microscopy (FESEM) image obtained shows that most of the entire areas, a thicker carbon products forest/agglomerated was formed on the top surface of YEF 50 substrate. Meanwhile, the transmission electron microscopy (TEM)image reveals that the VACNT on Co/Al2O3/SUS 310S are multi-walled CNTs (MWCNTs) with the inner and outer diameter of CNTs are approximately 4.89 nm and 16.43 nm, respectively. The Raman spectra results indicate that the CNT was typical of MWCNTs,which is in agreement with the TEM observation. Regardless of the difference in current collectors being used, cyclic voltammetry (CV) analysis from the EC depicted a relatively good specific gravimetric capacitance (Csp) and rate capability performance. A nearly rectangular-shaped CV curve was observed even at a scan rate of 1000 mV s−1. The Csp measured at 1 mV s-1 was 33.35 F g-1 (SUS 310S), 16.73 F g-1 (Inconel 600), and 24.82 F g-1 (YEF 50), respectively. Besides, from the charge-discharge measurement, the symmetrical triangular curves reveal that there is no IR drops or voltage drops because of low internal resistance in the electrode for SUS 310S, Inconel 600, and YEF 50 substrates. Also, the VACNT electrode shows excellent discharge behaviour and good capacitance retention of up to 1,000 cycles. Thus, this binder free and aligned CNT structure may provide excellent rate capabilities, high capacitance, and long lifecycle energy device. This is very promising for then development of high energy and high power density of device for multi-scale applications or industries

Electrochemical performance of activated carbon and graphene based supercapacitor

A conventional but simple fabrication technique of activated carbon/graphene (AC/G) supercapacitor electrode will be presented in this work. The AC/G electrode was prepared using slurry technique from the mixture of AC and graphene powders, polytetrafluoroethylene as binder and N-methylpyrrolidone as solvent. The AC/G electrode was dried at 120uC in vacuum oven for 6 h followed by immersing in 1M lithium hexafluorophosphate electrolyte for another 6 h. The specific gravimetric capacitance of the electrode was calculated to be 19.45 F g21 using cyclic voltammetry at a scan rate of 1 mVs-1. Electrochemical behaviour including charge discharge and impedance characteristics confirmed the electrode’s ability as a possible active material for use in carbon based supercapacitor

Electrochemical Performance Of Molybdenum Disulfide Supercapacitor Electrode In Potassium Hydroxide And Sodium Sulfate Electrolytes

Two-dimensional materials have attracted growing interest in research because of their specific electronic, physical, optical and mechanical properties. Molybdenum disulfide was theoretically investigated as novel energy storage materials because of its unusual physicochemical properties. This paper describes easy approach to fabricate molybdenum disulfide (MoS2) electrode using slurry technique on conducting substrate namely Ni foam as current collector for supercapacitor device application. This MoS2 electrode exhibits relatively good specific gravimetric capacitance, (Csp) of 11.12 to 12.38 Fg-1 at 1 mVs-1 scan rate. Moreover, galvanostatic charge-discharge displays symmetrical triangular curves which attributed to the fast charge-discharge process (in seconds). These results show that MoS2 active material can be charged and discharged reversibly between 0.2 and 1.0 V (in 6 M KOH) and between 0.3 and 1.0 V (in 0.5 M Na2SO4). From cyclic stability test exhibits capacitance retention of up to 83% and 64% after 1000 cycles in 6 M KOH and 0.5 M Na2SO4, respectively. The MoS2 electrode is thus a promising material for future application of the supercapacitor

Carbon nanomaterials derived from Malaysia’s highway road asphalt waste as electrode for supercapacitor

Developing cost-effective and environmental friendly electrode material for supercapacitor is critical for energy storage technologies. The fabrication of asphalt waste carbon (AWC) combined with multi-walled carbon nanotube (MWCNT) supercapacitor electrode was performed by using conventional slurry technique. The AWC/MWCNT composite electrode was compared to that of non-mixed AWC electrode. For non-mixed AWC electrode, the specific gravimetric capacitance (Csp) was 1.93 F g-1 at 1 mV s-1 scan rate and the Csp obtained for AWC/MWCNT electrode was 62.94 F g-1. From charge-discharge analysis, the AWC/MWCNT electrode showed nearly symmetrical triangular shapes at different current densities (0.5 to 15 A g-1). It was also clear that the Csp remains about 80% of the initial capacitance after 800 cycles at 15 A g-1 current density, indicating that AWC/MWCNT electrode possessed good ion accessibility and cycling stability

Control of Cobalt Catalyst Thin Film Thickness by Varying Spin Speed in Spin Coating towards Carbon Nanotube Growth

Cobalt (Co) catalyst thin film is an active metal catalyst that can be very helpful to grow carbon nanotubes (CNTs). The catalyst thin films were prepared on silicon wafers by spin coating the solution of cobalt acetate tetrahydrate and ethanol. The effects of different spin speed parameter during the spin coating process were investigated. The findings showed that the optimum thickness of the Co catalyst thin films, i.e., 12.1 nm, was obtained at the highest spin speed of 8000 rpm. The uniformity of the thin films was also found to increase with increasing spin speed. The study also demonstrated that single-walled carbon nanotubes could be grown from Co catalyst particles after the catalytic chemical vapor deposition of ethanol. The particle and thickness analysis, as performed by means of FESEM while the existence of CNTs, was performed by Raman spectroscopy

Structural Characterization And Electrochemical Performance Of Nitrogen Doped Graphene Supercapacitor Electrode Fabricated By Hydrothermal Method

The introduction of nitrogen (N) into graphene is of great focus as it escalates overall device performance as the introduction of N atoms improves the electronics of the graphene. In this work, the N-doped graphene electrode was prepared by using hydrothermal method where graphene nanoplatelet was used as active material and aqueous ammonia as the nitrogen source. The electrode was then used as the supercapacitor electrode. From Raman analysis, the ID/IG ratio of N-doped graphene has a higher value than that of pristine graphene. This indicates the N-doped graphene possessed more defects and has a higher degree of disorder within the graphene sheet. For X-ray diffraction analysis, the result exhibits a broad peak at 2θ = 26.3o, corresponding to the graphitic profile with an interlayer spacing of 3.57 Å. X-ray photoelectron spectroscopy analysis proved that there is a presence of nitrogen on the graphene surface, with 2.35 % of the atomic concentration. From the cyclic voltammetry, all curves showed an almost rectangular shape at the scan rates of 10 to 100 mVs-1. The calculated specific gravimetric capacitance is 25.2 F g-1 at 10 mV s-1. In addition, charge-discharge analysis confirmed the typical behavior of electric double layer capacitor from the linear symmetric slope

Preparation Of Graphene/Molybdenum Disulfide Based Electrodes And Its Electrochemical Performance In Supercapacitors

Supercapacitor is highly promising energy device due to its electrical charge storage performance and significant lifecycle ability. Construction of the supercapacitor cell especially its electrode fabrication is critical to ensure great application performance. The purpose of this research is to fabricate the molybdenum disulfide (MoS2), graphene and G/MoS2 hybrid electrode and their usage as symmetric and asymmetric supercapacitors. The electrode was prepared by using a simple and facile slurry technique. By this, XRD was used to analyze the crystal phase and structure of the as-prepared graphene, MoS2, and G/ MoS2 hybrid. The peaks at 14.3°, 33.8°, and 57.5° are attributed to the (002), (100), and (110) plane of MoS2 crystal. From Raman spectroscopy shows the characteristic peaks of graphene (D, G and 2D) and MoS2 (E12g band at 377 cm-1 and A1g band at 403 cm-1) are retained in the Raman spectra of G/MoS2 which can confirm the fact that the hybrid of G/MoS2 is composed of MoS2 and graphene. Next, the XPS analysis was carried out to deduce the exact elemental composition of the G/MoS2. The full scan of the G/MoS2 gives the characteristic peaks for Mo 3d, S 2p, C ls and 0 ls with their corresponding binding energies. The morphologies and microstructures of the MoS2, graphene and G/MoS2 are systematically characterized by FESEM observation. The high resolution of FESEM image further reveals that the MoS2 structures are constructed with layers of nanosheets. Meanwhile, FESEM image of graphene sheets illustrating the uniformly distributed of graphene into the Ni foam. Also, the inclusion of MoS2 nanosheets resulted in a rough surface, logically due to co-stacking of MoS2 nanosheets over the graphene nanosheets. Further, the morphology of the G/MoS2 was examined by TEM and reveals the crystal lattice structure of MoS2 and graphene in G/MoS2. The interlayer spacing of MoS2 in the hybrid were estimated to be -0.63 nm, which can be indexed to their (002) lattice planes of hexagonal phase of MoS2. Regardless of the difference in electrode being used, cyclic voltammetry (CV) analysis from the supercapacitor depicted a relatively good specific gravimetric capacitance (Csp) and rate capability performance. A nearly rectangular-shaped CV curve was observed even at high scan rate. Besides, from the charge-discharge measurement, the symmetrical triangular curves reveal that there is no IR drops or voltage drops because oflow internal resistance in the electrodes. Also, the electrode shows excellent discharge behavior and good capacitance retention of up to 10,000 cycles. Thus, this 2D heterostructures may provide excellent rate capabilities, high capacitance, and long lifecycle energy device. This is very promising for the development of high energy and high power density of device for multi-scale applications or industries

Direct deposition of multi-walled carbon nanotubes onto stainless steel and YEF foils using a simple electrophoretic deposition for electrochemical capacitor electrode

Metals including metal alloys have been widely used as current collector in energy storage devices. Many papers reported the direct deposition of carbon materials like multi-walled carbon nanotube (MWCNT) onto aluminum or copper or stainless steel foils. However, it is important to note that the study of YEF 50, an engineering iron alloy and high performance stainless steel SUS 310S as current collector is very limited. This manuscript discusses the usage of electrophoretic deposition technique using the MWCNT colloids in isopropyl alcohol electrolyte during the direct deposition. Other than CNT characterization using several analytical techniques, electrochemical analyses confirmed the excellent capacitive performance of MWCNT electrode with the evidence of small internal resistance. From cyclic voltammetry measurement at 1 mV s−1, a relatively high specific gravimetric capacitance of 124 F g−1 and 89 F g−1 for YEF 50 and SUS 310S, respectively were obtained. Other than the intrinsic properties of the CNTs, the excellent capacitance is attributed to the polyvinyl alcohol react as adhesivematerial between MWCNT and the surface of conductive substrat

Graphene/transition metal dichalcogenides hybrid supercapacitor electrode: status, challenges, and perspectives

Supercapacitors, based on fast ion transportation, are among the most promising energy storage solutions that can deliver fast charging–discharging within seconds and exhibit excellent cycling stability. The development of a good electrode material is one of the key factors in enhancing supercapacitor performance. Graphene (G), an allotrope of carbon that consists of a single layer of carbon atoms arranged in a hexagonal lattice, elicits research attention among scientists in the field of energy storage due to its remarkable properties, such as outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior. Furthermore, numerous studies focus on 2D materials that are analogous to graphene as electrode supercapacitors, including transition metal dichalcogenides (TMDs). Recently, scientists and researchers are exploring TMDs because of the distinct features that make 2D TMDs highly attractive for capacitive energy storage. This study provides an overview of the structure, properties, synthesis methods, and electrochemical performance of G/TMD supercapacitors. Furthermore, the combination of G and TMDs to develop a hybrid structure may increase their energy density by introducing an asymmetric supercapacitor system. We will also discuss the future prospect of this system in the energy field

Preparation Of Hydrous Ruthenium Oxide/Activated Carbon Electrode And Its Supercapacitive Performance In 6 M KOH

Hydrous ruthenium oxide (RuO2) and activated carbon (AC) denoted as RuO2/AC composite electrodes were prepared by combining sol–gel and conventional slurry processing techniques. In this paper, several different compositions of composite electrode slurries were fabricated using RuO2 and AC powders. Benefits from the combined advantages of both RuO2 and AC in such a unique structure were the RuO2/AC composite electrode supercapacitors exhibited the specific capacitance (5.10 F g-1 for RuO2 50 wt%) and also have good cycling stability. These findings demonstrated the importance and great potential of RuO2/AC composites in the development of the energy-storage system especially for the high power supercapacitor electrode