Hybrid Supercapacitor Applications Research Articles

Mixed metals oxides with strong synergetic electrochemistry as battery-type electrodes for ultrafast energy storage

The mixed metal oxides with high conductivity and multi-metal centers could easily meet the growing needs of high performance energy-storage materials. Herein, ternary phase aluminum-nickel-cobalt oxide (AlNiCo-O) is facilely prepared by a hot-air oven-based method with a subsequent calcination. The as-obtained AlNiCo-O flower-like network makes fully use of the synergistic effects among the transition metals, and exploits more electro-active surface sites, thereby allowing to undergo the redox reactions more efficient. The AlNiCo-O electrode exhibits better charge storage performances with a remarkable specific capacity of 1008.5 C g−1 at 1 A g−1. Furthermore, the hybrid supercapacitor based on AlNiCo-O electrode exhibits a high energy density of 63.3 W h kg−1 at the power density of 881.4 W kg−1, good rate capability (41.6 W h kg−1 at 13.3 kW kg−1) and a satisfying cycling performance of 84.27% after 5000 cycles. This work proposes a feasible design of high-efficiency metal oxides for application in hybrid supercapacitors.

Flake-like MoS2 nano-architecture and its nanocomposite with reduced Graphene Oxide for hybrid supercapacitors applications

In this article, we have synthesized flake-like MoS2 nanoarchitecture by urea assisted hydrothermal method. To improve the electrical and electrochemical properties of MoS2 nanoarchitecture, we formed its nanocomposite (MoS2/r-GO) with 10% r-GO. After the addition of 10% r-GO, the nanocomposite shows the electrical conductivity of 1.24 × 10−1 Sm−1 that is higher than the pure MoS2 (2.2 × 10−7 Sm−1). The prepared nanocomposite also showed higher specific capacitance (441 Fg-1 at 1 Ag-1) than the pure MoS2 nanoarchitecture (248 Fg-1 at 1 Ag-1). Moreover, nanocomposite lost just 15.8% of its initial capacitance after 1000 charge-discharge cycles. The enhanced electrochemical activity of the nanocomposite is due to its unique flake-like structure and its reduced charge transfer resistance (Rct ~ 23.5 Ω). The 2-D flake-like structure of the electrode increased its contact area with the r-GO matrix and electrolyte. The higher electrical conductivity and specific surface area of the nanocomposite facilitated the faradaic and non-faradic charge storage mechanism. The r-GO matrix not only acted as a capacitive supplement but also facilitated the redox reaction because of its superior electrical conductivity. As the nanocomposite showed CV and CCD profiles in the negative potential window (−1 V to −0.53 V), therefore it has the potential to be used as a negative electrode material for hybrid supercapacitors applications. The observed results revealed the potential of the (MoS2/r-GO) nanocomposite-based cathode for hybrid supercapacitor applications.

CoFe2O4 Nanoparticle-Decorated 2D MXene: A Novel Hybrid Material for Supercapacitor Applications

The development of highly efficient electrode materials for high power devices is one of the cutting-edge research areas in advanced energy applications. Recently, MXene has gained tremendous interest among the research community because of its extraordinary electrochemical properties as compared to other two-dimensional layered materials such as graphene/MoS₂. However, the supercapacitive performance of MXene as an electrode material is hindered by the restacking of its layers due to functional group interactions. To overcome this problem, here in this article, we explored MXene and its composites with cobalt ferrite [CoFe₂O₄] nanoparticles (CoF NPs) for battery-like hybrid supercapacitor applications. NPs were applied to use them as interlayer spacers between MXene layers. By the electrochemical studies, it is proved that the composite (CoF/MXene) can provide better electrochemical properties than individual ferrite or MXene. The maximum specific capacitance (Cₛₚ) of CoF NPs, MXene, and CoF/MXene composites was observed to be about 594, 1046.25, and 1268.75 Fg–¹ at 1 A g–¹, respectively. The calculated specific capacity (sp. capacity) of the CoF/MXene composite was about 440 Cg–¹ at 1 A g–¹ and proved to be an excellent hybrid electrode material by providing only 0.25 Ω charge transfer resistance. The as-synthesized material demonstrated the excellent capacitance retention, about 97%, up to 5000 cycles.

A robust 2D porous carbon nanoflake cathode for high energy-power density Zn-ion hybrid supercapacitor applications

The exploration of next-generation energy storage devices with long cycle life, superior stability, large specific capacity, ultrahigh power and energy density have attracted increased interests in recent years. However, it still remains a tremendous challenge for conventional energy storage devices to achieve the merits of both batteries and supercapacitors. Herein, we present a convenient but effective approach to synthesize porous carbon nanoflakes (PCNFs) that process high specific surface area and tunable pore size distributions. We found the amount of activating reagent has a profound influence on the morphology and textural structure of the resulting products, and a chemical etching process to transform nanocages into nanoflakes has been proposed. Importantly, Zn-ion hybrid supercapacitor with PCNFs as cathode and Zn foil as anode can overcome the disadvantages of poor rate capability and low energy density for the conventional batteries and supercapacitors. The optimized PCNFs based Zn-ion hybrid supercapacitor can deliver an ultrahigh specific capacitance, excellent rate performance, outstanding cycling stability, and impressive energy density. The facile synthetic procedure combined with its excellent electrochemical performances endow the present devices a huge possibility to be used in future electrochemical energy storage systems.

Oxalic acid assisted rapid synthesis of mesoporous NiCo2O4 nanorods as electrode materials with higher energy density and cycle stability for high-performance asymmetric hybrid supercapacitor applications

In this study, mesoporous nickel cobaltite (NiCo2O4) nanorods as electrode materials for high-performance hybrid supercapacitor were fabricated onto Ni foam by a simple and cost effective oxalic acid (OA) assisted rapid co-precipitation method. The effects of different metal precursors (NCO-Nitrate, NCO-Chloride and NCO-Acetate) on the electrochemical capacitive properties were studied. FE-SEM analysis confirmed that all samples exhibited highly dense mesoporous NiCo2O4 nanorods vertically grown on the surface of Ni foam with excess accessible surfaces and unique sizes and morphologies. The resultant NiCo2O4 nanorod electrodes (for NCO-Nitrate, NCO-Chloride and NCO-Acetate) delivered the maximum specific capacitances of 790, 784, 776 F g−1 at the current density of 1 A g−1 with ultra-high capacitance retention of 82.27, 81.63 and 81.71% even at 20 A g−1 and excellent cyclic stability of 84.25, 83.33 and 83.24% capacitance retention at 5 A g−1 after 5000 cycles. The asymmetric supercapacitor (ASC) device was also sandwiched by using NCO-Nitrate as positive electrode and N-doped graphene hydrogel (NGH) as negative electrode. The fabricated ASC device delivered superior energy density (42.5 W h kg−1) at high power density (746.34 W kg−1) with excellent long cyclic stability (90% initial capacitance retention after 5000 cycles at 5 A g−1).

Facile one pot sonochemical synthesis of CoFe2O4/MWCNTs hybrids with well-dispersed MWCNTs for asymmetric hybrid supercapacitor applications

In this study, a facile sonochemical strategy is used for the fabrication of CoFe2O4/MWCNTs hybrids as an electrode material for supercapacitor applications. FE-SEM image demonstrates the uniformly well-distributed MWCNTs as well as porous structures in the prepared CoFe2O4/MWCNTs hybrids, suggesting 3D network formation of conductive pathway, which can enhance the charge and mass transport properties between the electrodes and electrolytes during the faradic redox reactions. The as-fabricated CoFe2O4/MWCNTs hybrids with the MWCNTs concentration of 15 mg (CFC15) delivers maximum specific capacitance of 390 F g−1 at a current density of 1 mA cm−2, excellent rate capability (275 F g−1 at 10 mA cm−2), and outstanding cycling stability (86.9% capacitance retention after 2000 cycles at 3 mA cm−2). Furthermore, the electrochemical performance of the CFC15 is superior to those of pure CoFe2O4 and other CoFe2O4/MWCNTs hybrids (CFC5, CFC10 and CFC20), indicating well-dispersion MWCNTs and uniform porous structures. Also, as-fabricated asymmetric supercapacitor device using the CoFe2O4/MWCNTs hybrids as the positive electrode and activated carbon as the negative electrode materials shows the outstanding supercapacitive performance (high specific capacitance, superior cycling stability and good rate capability) for energy storage devices. It delivers a capacitance value of 81 F g−1 at 3 mA cm−2, ca. 92% retention of its initial capacitance value after 2000 charge-discharge cycles and excellent energy density (26.67 W h kg−1) at high power density (~319 W kg−1).

Enhanced electrochemical performance of hollow Cu-Co selenide for hybrid supercapacitor applications

In this paper, the bimetallic Cu-Co selenide with well-defined hollow nanostructures has been successfully prepared through a simple hydrothermal selenization process. When utilized as the electrode material, the as-synthesized nanostructures can exhibit good capacity performance of 503 C g−1 (139.7 mAh g−1) at 10 mA cm−2, and also show good capacity retention (~ 70%) within the wide testing current region. Moreover, a hybrid supercapacitor based on this well-defined Cu-Co selenide and activated carbon has been successfully assembled. Within the potential window of 1.6 V, the maximum specific capacity of 132 C g−1 and the energy density of 29.5 Wh kg−1 are also demonstrated. The electrochemical behaviors presented in three- and two-electrode systems show that this bimetallic compound mentioned here has possible usage in the field of energy storage.

Polycationic bimetallic oxide CoGa2O4 with spinel structure: dominated pseudocapacitance, dual-energy storage mechanism, and Li-ion hybrid supercapacitor application

In this work, the polycationic bimetallic oxide CoGa2O4 with spinel structure was successfully prepared by simple hydrothermal and subsequent calcination methods. Following, half-cell electrochemical test showed that this material presented a hybrid energy storage mechanism, namely combining Ga alloying and Co3O4 conversion. The combination of the two energy story mechanisms makes CoGa2O4 have higher conductivity than other single metal oxides. According to the calculation of the relationship between peak current and sweep speed, the b = 0.93 of CoGa2O4 is obtained, and its electrochemical behavior is closer to capacitive behavior than that of Co3O4 and NiCo2O4. This makes it have excellent rate performance and cycle stability. Consequently, the CoGa2O4//AC Li-ion hybrid supercapacitor (LIHSC) device exhibits excellent cycling stability (capacity retention of 83% after 8000 cycles), high-energy density of 111.5 Wh kg−1 (at 100 W kg−1), and high power density of 3927 W kg−1 (at 24 Wh kg−1).

Influence of electrochemically deposited polypyrrole layers on NiCo2O4-decorated carbon fiber paper electrodes for high-performance hybrid supercapacitor applications

The electrochemically polypyrrole (PPy) layer deposited on NiCo2O4-decorated carbon fiber paper (PPy-NiCo2O4@CFP) composites was prepared by a consecutive two-step process. At first, the hierarchically NiCo2O4-decorated CFP (NiCo2O4@CFP) composite was prepared by a low temperature hydrothermal method. Secondly, the PPy layer was deposited onto the NiCo2O4@CFP composites using an electrochemical deposition method. The potential sweeping between −0.2 and 1.0 V was performed at a scan rate of 50 mV s−1 for various (0, 5, 10, 15 and 20) cycles in the presence of a pyrrole monomer. SEM images clearly indicated that the NiCo2O4 nanostructures were uniformly grown over the CFP. Further, the PPy layer was also uniformly hierarchically-deposited over the NiCo2O4@CFP composites. The surface morphologies of the obtained PPy-NiCo2O4@CFP composites were dramatically changed depending on the electrodeposition cycles of PPy. We have prepared various PPy-NiCo2O4@CFP hybrid composites with different electrodeposition cycles of PPy layers, and the effects of electrodeposited PPy layers were investigated. The PPy-NiCo2O4@CFP composites with the 15 cycles electrodeposited PPy layers (PPy15-NiCo2O4@CFP//N-rGO@CFP) showed a maximum specific capacitance of ~239 F g−1 at 2 A g−1 and excellent energy density of 64.95 Wh kg−1 at a power density of 1400.2 W kg−1.

Enhanced Performance of Cobalt Vanadium Oxide upon Doping with Sulfur for Hybrid Supercapacitor Application in Aqueous and Non-Aqueous Medium

Cobalt Vanadate is one of the electroactive material for charge storage application due to earth abundant and environment friendly nature of cobalt. Further, vanadate system renders the material with multiple stable oxidation states, high electrical and ionic conductivity and high rate capability. However, the electrochemical performance of cobalt vanadate is limited either by high resistance of binder material or by the introduction of dead weight during electrode fabrication. This limitation can be circumvented by in-situ synthesis of cabalt vanadate onto current collector. Further, the doping of Sulfur in cobalt vanadate matrix significantly improves the electrochemical performance by improving the electrical conductivity. Herein, we report binder-free synthesis of Sulfur doped cobalt vanadate (S-Co3V2O8) nanosheet arrays on Ni foam using hydrothermal approach. The hydrothermally synthesized S-Co3V2O8 achieves nanosheet morphology with height and thickness of ~200 nm and ~10 nm, respectively wherein the size remains unchanged before and after the doping of sulfur in Co3V2O8. Further, the increased duration of hydrothermal reaction increases the thickness of synthesized nanosheet. We found that the electrochemical performance of Sulfur doped Co3V2O8 is ~25% more as compared to its undoped Co3V2O8 counterpart. In 6M KOH aqueous electrolyte, S-Co3V2O8 nanosheet array shows a specific capacity of 1476 C/g (3690 F/g) at 2 A/g. Further, the material exhibits enhanced rate capability and excellent capacity retention of 94.2% at 5 A/g specific current after 4000 cycles. The introduction of sulfur into vanadate matrix improves the electrochemical performance due to low electronegativity and large size of sulfur as compared to oxygen, which improves the charge transport properties, charge storage capacity with highly robust structure. An asymmetric supercapacitor device fabricated using S-Co3V2O8 as cathode and active carbon (AC) as anode shows specific capacity (or capacitance) of 174.5 C/g (or 116.33 F/g), energy density (36.4 Wh/kg) and power density (740 W/kg) at 2 A/g with 98.4% capacity retention after 4000 cycles. Further, the electrochemical performance of S-Co3V2O8 has been checked in 1M LiPF6 in non-aqueous electrolyte as Li-ion hybrid capacitor. The capacitor fabricated in a CR2032 coin cell exhibits specific capacity of 994 mAh/g with energy density of 695 W/kg at specific current of 1 A/g with good rate capability and 46.5% capacity retention after 100 cycles which makes it a potential candidate for robust high electrochemical energy storage system.

Three-dimensional network-like amorphous NiCo-LDH nanofilms coupled with Co3O4 nanowires for high-performance supercapacitor

A network-like structure consisting of an amorphous nickel–cobalt layered double hydroxide nanofilm anchored to Co3O4 nanowires (Co3O4/NiCo-LDH) is grown on nickel foam via hydrothermal reaction and electrochemical deposition. The complex interlocking network-like structure provides three-dimensional interconnected porous channels for electron transport and ion diffusion, and provides optimal access to active sites; this results in rapid Faradaic redox reactions. This intriguing advantage gives the optimal Co3O4/NiCo-LDH electrode outstanding electrochemical performance, with an ultrahigh specific capacity of 1067 C g-1, and high rate performance, with 73.28% capacity retention at 20 A g-1. When it is combined with an activated carbon (AC) electrode, the Co3O4/NiCo-LDH//AC device exhibits a maximum energy density of 74.4 Wh kg-1 at a power density of 989 W kg-1 and excellent cycling stability, with 91.57% retention after 7000 cycles. This study provides new options and an important foundation for rational design of network-like structures for application in hybrid supercapacitors.

Nanocarbon Composites for Energy Storage Applications

In my talk, I will introduce our recent work on energy storage nanocarbon composite materials. Several structural designs of graphene and nano silicon anode composites were prepared for high energy density lithium ion battery; We also produced double-shell of graphene and artificial solid state electrolytes, such as Li7P3S11(LPS), Li4SiO4, LiAlO2, encapsulated commercial Si nanoparticles structure for LIB anode with excellent cycling stability and superior rate capability. A simple ball milling method was found to be a suitable method to produce nano-sized LiMn2O4and nanocarbon (graphene, carbon nanotubes, or super P) composites for high performance hybrid supercapacitor application. I will also introduce our work using porous nanocarbons as Li host materials for Lithium metal battery application. Ref: Ai Q., Ci L., et al., Diamond and Related Materials 88, 60 (2018)Chen L., Ci L., et al., Journal of Power Sources 392, 116 (2018)Xu X., Ci L., et al., Electrochimica Acta 276, 325 (2018)Hou G., Ci L., et al., Journal of Power Sources 386,77 (2018)Ma X., Ci L., et al., Journal of Materials Chemistry A 6, 1574 (2018)Ma X., Ci L., et al., Scientific Reports 7, 9642 (2017)Zhai W., Ci L., et al., Nano Research 10, 4274 (2017) Feng J., Ci L., et al., Journal of Power Sources 287, 177 (2015)

Understanding Interlayer Deprotonation of Hydrogen Titanium Oxide for High-Power Electrochemical Energy Storage

Negative electrode materials that possess fast lithium insertion kinetics are in high demand for high power lithium-ion batteries and hybrid supercapacitor applications. In this work, hydrogen titanium oxides are synthesized by a proton exchange reaction with sodium titanium oxide, resulting in the H2Ti3O7 phase. We show that a gradual water release in four steps yields intermediate phases of hydrogen titanate with different degrees of interlayer protonation. In addition, a synthesis route using zinc nitrate is explored yielding H2Ti3O7 with a high rutile content. This material dehydrates already at a lower temperature, resulting in a lamellar rutile titania phase. The hydrogen titanate materials with partially protonated interlayers are tested as negative electrodes in a lithium-ion battery and hybrid supercapacitor setup, showing an improved performance compared to the fully protonated phases. The performance in half-cells reaches around 168 mAh/g, with high retention of 42 mAh/g at 10 A/g. This transla...

Hydrothermally Tailored Three-Dimensional Ni-V Layered Double Hydroxide Nanosheets as High-Performance Hybrid Supercapacitor Applications.

Here, we report a facile and easily scalable hydrothermal synthetic strategy to synthesize Ni–V layered double hydroxide (NiV LDH) nanosheets toward high-energy and high-power-density supercapacitor applications. NiV LDH nanosheets with varying Ni-to-V ratios were prepared. Three-dimensional curved nanosheets of Ni0.80V0.20 LDH showed better electrochemical performance compared to other synthesized NiV LDHs. The electrode coated with Ni0.80V0.20 LDH nanosheets in a three-electrode cell configuration showed excellent pseudocapacitive behavior, having a high specific capacity of 711 C g–1 (1581 F g–1) at a current density of 1 A g–1 in 2 M KOH. The material showed an excellent rate capability and retained the high specific capacity of 549 C g–1 (1220 F g–1) at a current density of 10 A g–1 and low internal resistances. Owing to its superior performance, Ni0.80V0.20 LDH nanosheets were used as positive electrode and commercial activated carbon was used as negative electrode for constructing a hybrid supercapacitor (HSC) device, having a working voltage of 1.5 V. The HSC device exhibited a high specific capacitance of 98 F g–1 at a current density of 1 A g–1. The HSC device showed a higher energy density of 30.6 Wh kg–1 at a power density of 0.78 kW kg–1 and maintained a high value of 24 Wh kg–1 when the power density was increased to 11.1 kW kg–1. The performance of NiV LDHs nanosheets indicates their great potential as low-cost electrode material for future energy-storage devices.

Three-dimensional core-shell NiCoP@NiCoP array on carbon cloth for high performance flexible asymmetric supercapacitor

Transition metal phosphides (TMPs) have been received widespread research attention and developed as electrode materials for their superior electrical conductivity and excellent redox activity. In this work, self-supported three-dimensional hierarchical core-shell NiCoP@NiCoP@CC electrode has been fabricated by a two-step hydrothermal and a phosphorization method, in which NiCoP@NiCoP core-shell leaf-like arrays are directly grown on carbon cloth. The electrode integrates the advantages of the 1D core for “hyperchannel” of the electron transport, 2D shell on core for a short diffusion distance for the ions and also the charge carrier meanwhile improvement of cycle stability, and 3D networked substrate for flexibility. The as-fabricated electrode shows superior electrochemical performance and delivers a high specific capacity of 1125 C g−1 (312 mAh g−1) at 1 A g−1, and outstanding rate capability with 78.0% retention even at 10 A g−1 and still retain 808 C g−1 (224 mAh g−1) (71.8% retention) after 2000 cycles. In addition, the asymmetric supercapacitor has also been assembled for actual use by employing NiCoP@NiCoP electrode as the anode and the activated carbon (AC) as the cathode, which displays a voltage window of 1.5 V and a high energy density of 34.8 Wh kg−1 at a power density of 750.0 W kg−1. The results demonstrate feasibility of NiCoP@NiCoP core-shell array on carbon cloth as electrode material for high performance hybrid supercapacitor applications.

Effective synthetic strategy for Zn0.76Co0.24S encapsulated in stabilized N-doped carbon nanoarchitecture towards ultra-long-life hybrid supercapacitors

Fabrication of the stabilized Zn0.76Co0.24S encapsulated in a hollow N-doped carbon multicomponent electrode and the application in hybrid supercapacitors.

A novel ordered hollow spherical nickel silicate–nickel hydroxide composite with two types of morphologies for enhanced electrochemical storage performance

Nickel silicate–nickel hydroxide composite with two morphologies was synthesized for application in high-performance hybrid supercapacitors.

Porous interconnected NiCo2O4 nanosheets and nitrogen- and sulfur-codoped reduced graphene oxides for high-performance hybrid supercapacitors

We demonstrate a facile hydrothermal synthesis of the interconnected porous NiCo2O4 nanosheets for hybrid supercapacitor applications. The as-synthesized NiCo2O4 nanosheets show a high specific capacitance of 3137 F g−1 at a current density of 2 A g−1, which is much greater than 1916 and 1251 F g−1 of Co3O4 and NiO, respectively. Interestingly, the total specific capacitance of the NiCo2O4 is almost close to the sum of the specific capacitance of the NiO and Co3O4. Furthermore, a hybrid supercapacitor is configured with the NiCo2O4 nanosheets and the nitrogen- and sulfur-codoped reduced graphene oxide as the positive and negative electrodes, respectively. This hybrid supercapacitor delivers a maximum energy density of 33.64 W h kg−1 at a power density of 1196 W kg−1 and excellent long-term cyclic stability over 12,000 charge/discharge cycles at the enlarged voltage window of 1.5 V. The remarkable supercapacitive performances of the hybrid device are attributed to the interconnected porous structure of NiCo2O4 nanosheets and three-dimensional continuous macropores of codoped reduced graphene oxides.

Controllable synthesis of nanohorn-like architectured cobalt oxide for hybrid supercapacitor application

We demonstrate a facile and controllable synthesis of horn-like Co3O4 nanostructures through a solvothermal process followed by calcination at different temperatures. The particle sizes and defects of the as-obtained Co3O4 nanohorns are controlled with respect to calcining temperatures, while preserving the horn-like morphology. In particular, the Co3O4 nanohorn electrodes prepared at 300 °C reveal the specific capacitance of ∼2751 F g−1 and the rate capability of 46.8%, which is greater than those of materials obtained at 350, 400, and 450 °C. In order to enlarge the potential window, a hybrid supercapacitor is configured with the Co3O4 nanohorn and activated carbon used as positive and negative electrodes, respectively. The as-fabricated hybrid supercapacitor shows high specific capacitance of ∼101 F g−1 and the rate capability of 80.5%. The energy and power densities of hybrid supercapacitor are ∼31.70 W h kg−1 and 16.71 kW kg−1, respectively, along with 91.37% of capacitance retention over 350,000 cycles. These energy and power densities of the hybrid supercapacitors are approximately 8.5 and 3.5 times greater than values of Co3O4 symmetric supercapacitor.

Electroless Growth of High Surface Area Au Dendrites with Corrugated Edge Structure for Hybrid Supercapacitor Applications

AbstractEnergy storage applications demand for high surface area materials having moderate conducting nature along with redox behavior for increased energy density and power density. We report, development of hybrid material of dendritic Au structure coated with iron oxide with high surface area that combines both electric double layer capacitance and pseudocapacitance. One step electroless method is used for the rapid growth of gold dendritic microstructure followed by sputter coating of Fe2O3 to make hybrid material for supercapacitor application. Time dependent growth evolution reveals that the dendritic stem and lateral branches grow in length as a function of time. The lateral branches are found to be few tens of nm thick with sub 100 nm spacing among each other, providing high surface area as well as high catalytic activity. Electrochemical measurements confirm significant increase in supercapacitive performance including delayed discharging time and improved energy density (3.87 μWhr/cm2). Dendritic Au‐Fe2O3 hybrid materials can be a suitable candidate for energy storage material in normal and harsh operating conditions due to its microstructural stability and noble nature.