Electrode Material For Hybrid Supercapacitors Research Articles

Carbon-incorporated Janus-type Ni2P/Ni hollow spheres for high performance hybrid supercapacitors

Carbon-incorporated Janus-type Ni2P/Ni hollow spheres were synthesized and applied as electrode materials for hybrid supercapacitors for the first time.

Asymmetric Supercapacitors Using Chemically Prepared MnO2 as Positive Electrode Materials

Chemically prepared manganese dioxide (CMD), which is traditionally used as a cathode material for Li-ion batteries, was tested and characterized for the first time as a positive electrode material for hybrid supercapacitors with two different aqueous electrolyte solutions (6 M KOH and 0.5 M K2SO4). The CMD electrodes exhibit distinct electrochemical characteristics that depend on the electrolyte solution used. The CMD electrodes show higher specific capacitance in the basic electrolyte solution, 137 F/g, at a current density of 0.1 A/g. Asymmetric supercapacitors comprising CMD positive electrodes and activated carbon negative electrodes were fabricated and tested within an electrochemical window wider than the thermodynamic voltage limitation for aqueous solutions. The asymmetric supercapacitors based on KOH and K2SO4 showed very good electrochemical stability during more than 7000 charge–discharge cycles and reasonable energy and power density. The electrochemical performance of CMD/AC asymmetric supercapacitors, their easy assembly, and their low cost make these super capacitors promising as practical energy-storage devices.

Formation of Onion-Like NiCo2 S4 Particles via Sequential Ion-Exchange for Hybrid Supercapacitors.

Onion-like NiCo2 S4 particles with unique hollow structured shells are synthesized by a sequential ion-exchange strategy. With the structural and compositional advantages, these unique onion-like NiCo2 S4 particles exhibit enhanced electrochemical performance as an electrode material for hybrid supercapacitors.

Facile fabrication of large-area hybrid Ni-Co hydroxide/Cu(OH)2/copper foam composites

In this work, we have developed a versatile method for hybrid Ni–Co hydroxide array fabricated on copper foam (CF). Starting from commercial copper foam, the process involves sequential solution immersion and electrolytic deposition steps, both of which are simple and rapid to carry out and potentially scalable. The resulting Ni–Co hydroxide/Cu(OH)2/CF has a hierarchical and the nanoarray has a hollow structure, and exhibits outstanding electrochemical performance as battery-type electrode material for hybrid supercapacitors with excellent specific capacity (849.6Cg−1, at 5mAcm−2) and good cycling stability (81.03% of its initial capacity value was preserved after 5000 charge/discharge cycles at 100mAcm−2). Furthermore, an asymmetric supercapacitor was fabricated with the Ni-Co hydroxide/Cu(OH)2/CF as positive electrode while the rGO as negative electrode. The hybrid device exhibits excellent energy density of 58.61Whkg−1 at a power density of 359.33Wkg−1. Furthermore, we demonstrated that the process is also scalable in practice, by fabricating a large-size (20cm×30cm) Ni–Co hydroxide/Cu(OH)2/CF which retains excellent specific capacity.

Growth of three-dimensional hierarchical Co3O4@NiMoO4 core-shell nanoflowers on Ni foam as electrode materials for hybrid supercapacitors

In this work, we report a novel battery-type electrode of three-dimensional hierarchical Co3O4@NiMoO4 flower-like hybrid arrays on Ni foam synthesized with the combination of hydrothermal and post-annealing treatment. The Co3O4 nanowire arrays are utilized as scaffolds and interconnected NiMoO4 nanosheets are grown on the surface. The as-prepared Co3O4@NiMoO4 hybrid arrays exhibit outstanding electrochemical performance in terms of specific capacity (636.8C/g at 5mA/cm2) and cycling stability (84.1% retention over 2000 cycles at 20mA/cm2). The assembled hybrid supercapacitor device based on Co3O4@NiMoO4 and activated carbon as the positive and negative electrodes can achieve a high energy density of 58.5Wh/kg at 389W/kg, suggesting the great potential for applications in supercapacitors.

Flower-like nickel-cobalt hydroxides converted from phosphites for high rate performance hybrid supercapacitor electrode materials

Ni-Co hydroxides have been extensively studied as electrode materials for hybrid supercapacitors. In this work, we report an effective method to significantly improve the rate performance of Ni-Co hydroxides through engineering the dual-channel structure and tuning the valence state of Cobalt, which is realized through a facile in suit chemical treatment of phosphites. The specific capacitance of the obtained flower-like Ni-Co hydroxide electrode is 1425Fg−1 at 20Ag−1, which is 83.9% of 1698Fg−1 at 1Ag−1. Simultaneously, a moderate cycling stability with an efficiency of 80.6% after cycling 4000 times at a current density of 10Ag−1 is obtained. Moreover, an energy density of 40.1 Wh kg−1 at a power density of 801.2Wkg−1 has been achieved in an assembled aqueous asymmetric supercapacitor, using Ni-Co hydroxide as positive electrode material and activated carbon as negative electrode material. Our study shows that the chemical treatment evokes morphology and phase transformation and induces partial Co2+ conversion to a more conductive Co3+ state. And the electrochemical performance has a significant relationship with the microstructure and valence state of Cobalt.

Molybdenum disulfide / mesoporous carbon nanocomposite as electrode material for supercapasitors

The article describes the features of MoS2/mesoporous carbon nanocomposite creation and application as an electrode material for hybrid supercapacitors. The combination of these two materials improved the electrochemical characteristics in comparison with molybdenum disulphide or mesoporous carbon on their own; in particular the synergetic effect between them led to the reduction of internal resistance and increase of electric conductivity that are reflected in the maximum power of the capacitor. In spite of a large surface area of the mesoporous carbon obtained from the raw material of plant origin (2200 m2 g–1), the synthesized nanocomposite (430 m2 g–1) has almost twice higher specific capacity (57 Fg–1 and 110 Fg–1, respectively) due to the summary effect of EDL and faradaic processes in the material. The samples were characterized by X-ray difractometry (XRD), transmission electron microscopy (TEM), porosimetry, impedance spectroscopy, voltammetry, and chronopotentiometry.

1D Ni-Co oxide and sulfide nanoarray/carbon aerogel hybrid nanostructures for asymmetric supercapacitors with high energy density and excellent cycling stability.

The fabrication of supercapacitor electrodes with high energy density and excellent cycling stability is still a great challenge. A carbon aerogel, possessing a hierarchical porous structure, high specific surface area and electrical conductivity, is an ideal backbone to support transition metal oxides and bring hope to prepare electrodes with high energy density and excellent cycling stability. Therefore, NiCo2S4 nanotube array/carbon aerogel and NiCo2O4 nanoneedle array/carbon aerogel hybrid supercapacitor electrode materials were synthesized by assembling Ni-Co precursor needle arrays on the surface of the channel walls of hierarchical porous carbon aerogels derived from chitosan in this study. The 1D nanostructures grow on the channel surface of the carbon aerogel vertically and tightly, contributing to the enhanced electrochemical performance with ultrahigh energy density. The energy density of NiCo2S4 nanotube array/carbon aerogel and NiCo2O4 nanoneedle array/carbon aerogel hybrid asymmetric supercapacitors can reach up to 55.3 Wh kg-1 and 47.5 Wh kg-1 at a power density of 400 W kg-1, respectively. These asymmetric devices also displayed excellent cycling stability with a capacitance retention of about 96.6% and 92% over 5000 cycles.

General Formation of M(x)Co(3-x)S4 (M=Ni, Mn, Zn) Hollow Tubular Structures for Hybrid Supercapacitors.

A simple and versatile method for general synthesis of uniform one-dimensional (1D) M(x)Co(3-x)S4 (M=Ni, Mn, Zn) hollow tubular structures (HTSs), using soft polymeric nanofibers as a template, is described. Fibrous core-shell polymer@M-Co acetate hydroxide precursors with a controllable molar ratio of M/Co are first prepared, followed by a sulfidation process to obtain core-shell polymer@M(x)Co(3-x)S4 composite nanofibers. The as-made M(x)Co(3-x)S4 HTSs have a high surface area and exhibit exceptional electrochemical performance as electrode materials for hybrid supercapacitors. For example, the MnCo2S4 HTS electrode can deliver specific capacitance of 1094 F g(-1) at 10 A g(-1), and the cycling stability is remarkable, with only about 6% loss over 20,000 cycles.

General Formation of MxCo3−xS4 (M=Ni, Mn, Zn) Hollow Tubular Structures for Hybrid Supercapacitors

AbstractA simple and versatile method for general synthesis of uniform one‐dimensional (1D) MxCo3−xS4 (M=Ni, Mn, Zn) hollow tubular structures (HTSs), using soft polymeric nanofibers as a template, is described. Fibrous core–shell polymer@M‐Co acetate hydroxide precursors with a controllable molar ratio of M/Co are first prepared, followed by a sulfidation process to obtain core–shell polymer@MxCo3−xS4 composite nanofibers. The as‐made MxCo3−xS4 HTSs have a high surface area and exhibit exceptional electrochemical performance as electrode materials for hybrid supercapacitors. For example, the MnCo2S4 HTS electrode can deliver specific capacitance of 1094 F g−1 at 10 A g−1, and the cycling stability is remarkable, with only about 6 % loss over 20 000 cycles.

Hierarchical Tubular Structures Composed of Mn‐Based Mixed Metal Oxide Nanoflakes with Enhanced Electrochemical Properties

In this work, a simple strategy is developed to synthesize hierarchical tubular structures (HTS) of Mn‐based (Co‐Mn, Ni‐Mn, Cu‐Mn, Zn‐Mn) mixed metal oxides. The first step in the synthesis involves redox reaction mediated growth of nanoflakes on carbon nanofibers under hydrothermal conditions. After calcination in air, carbon nanofibers are removed and HTS of mixed metal oxides can be obtained with little structural deterioration. The resultant HTS are advantageous as electrodes for electrochemical energy storage. As an example, it is shown that the Co‐Mn‐HTS sample exhibits outstanding electrochemical performance as electrode materials for hybrid supercapacitors and lithium ion batteries.

Fabrication and electrochemical properties of cylindrical hybrid supercapacitor using H2Ti12O25 as anode material

We successfully prepare H2Ti12O25 by soft-chemical synthesis using Na2Ti3O7 compounds, prepared by Na+/H+ ion exchange and heating. Then, a cylindrical hybrid supercapacitor is fabricated by using H2Ti12O25 as anode and activated carbon as cathode. The specific capacitance of hybrid supercapacitor using H2Ti12O25 is 57Fg−1 higher than that of hybrid supercapacitor using Li4Ti5O12 (38Fg−1). The hybrid supercapacitor using H2Ti12O25 exhibit cycle performance with a capacitance retention of 65.3% available for battery application. The energy density is 35Whkg−1 at a power density of 179Wkg−1 and 4Whkg−1 at a power density of 5383Wkg−1. These results show that the H2Ti12O25 anode material is a promising electrode material for hybrid supercapacitor.

Preparation and characteristics of Li4Ti5O12 with various dopants as anode electrode for hybrid supercapacitor

Spinel-Li4Ti5O12 is successfully synthesized by a solid phase synthesis. The Li4Ti5O12 powders with various dopants (Al3+, Cr3+, Mg2+) synthesized at 800 °C are in accordance with the Li4Ti5O12 cubic spinel phase structure. The dopants are inserted into the lattice structure of Li4Ti5O12 without causing any changes in structural characteristics. In order to study the effect on various dopants, the hybrid supercapacitor is prepared by using un-doped Li4Ti5O12 and doped Li4Ti5O12 in this work. The electrochemical performance of the hybrid supercapacitor is characterized by impedance spectroscopy and cycle performance. The results show Cr3+ and Mg2+ dopants enhance the conductivity of Li4Ti5O12. Also, Al3+ substitution improves the reversible capacity and cycling stability of Li4Ti5O12. It is found that effect of dopant on the electrochemical performance of Li4Ti5O12 as electrode material for hybrid supercapacitor where the EDLC and the Li ion secondary battery coexist in one cell system.

Facile synthesis of α-MoO3 nanobelts and their pseudocapacitive behavior in an aqueous Li2SO4 solution

α-MoO3 nanobelts were successfully prepared by a facile hydrothermal method with sodium molybdate (Na2MoO4) as the Mo source and NaCl as the capping agent. The as-prepared products were characterized using Fourier transformation infrared spectrophotometry (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electronic diffraction (SAED) and their pseudocapacitive properties were investigated in a 0.5 M aqueous Li2SO4 solution by cyclic voltammetry (CV), chronopotentiometry (CP) and AC impendence. The results show that the dimensions of the as-prepared α-MoO3 nanobelts are 200–400 nm in width, ca. 60 nm in thickness and 3–8 µm in length. The redox potential for the α-MoO3 nanobelts is found in the range of −0.3 to −1.0 V vs. SCE, which indicates that the α-MoO3 nanobelts can be used as anode electrode materials for hybrid supercapacitors. The specific capacitances of the α-MoO3 nanobelts at 0.1, 0.25, 0.5 and 1 A g−1 are 369, 326, 256 and 207 F g−1, respectively. The maximum specific capacitance of the α-MoO3 nanobelts is much higher than those of MoO3 nanoplates with 280 F g−1, MoO3 nanowires with 110 F g−1 and MoO3 nanorods with 30 F g−1 recently reported in literature. Furthermore, the α-MoO3 nanobelt electrode exhibits a good cycle stability with more than 95% of the initial specific capacitance maintained after 500 cycles. Additionally, the present route to prepare nanostructured MoO3 is much less expensive than those with Mo powders as the Mo source. Overall, the obtained high performance α-MoO3 nanobelts could be a promising electrode material for supercapacitors.

Mesoporous manganese dioxide prepared under acidic conditions as high performance electrode material for hybrid supercapacitors

High surface area mesoporous manganese dioxide (MnO2) with α-phase crystalline structure has been synthesized by the reduction of potassium permanganate with ethylene glycol under acidic conditions. Nitrogen sorption analyses show that MnO2 synthesized under acidic conditions exhibits a type IV isotherm, indicating a mesoporous character. Electrochemical performances of MnO2 samples as supercapacitor electrode materials have been studied in a three-electrode system. A hybrid supercapacitor based on using a composite material (MnO2&Activated Carbon) as the positive electrode and activated carbon as the negative electrode has been fabricated. The hybrid supercapacitor fabricated using MnO2 synthesized under acidic conditions has excellent large current charge–discharge performance, and shows a practical cell voltage of 1.8V and a capacitance of 22.1Fg−1 after 1500 cycles even in the presence of the dissolved oxygen. MnO2 synthesized in the absence of acid shows poor cycle performance and a low capacitance.

Original Conductive Nano-Co3O4 Investigated as Electrode Material for Hybrid Supercapacitors

Cobalt oxides have been extensively used as conductive additives for Ni-MH batteries. We report in this paper the performances of an original nanometric cobalt oxide, close to Co3O4, as electrode material for hybrid supercapacitors. This spinel type phase contains hydrogen, lithium, cobalt vacancies, and especially Co4þ ions within the structure, leading to a high electronic conductivity. Cyclic voltammetry and impedance spectroscopy measurements show interesting capacitance (320 F/g in 8M-KOH), as well as good electrochemical cycling with a small amount of carbon black (5%).