Composites For Supercapacitors Research Articles

Synthesis of ZnO and NiO nano ceramics composite high-performance supercapacitor and its catalytic capabilities

NiO and ZnO mixed nanocomposites were manufactured using the solution combustion process. As-prepared samples were analyzed using XRD. The XRD shows an average crystallite size of 35–40 nm. The elemental composition determined by EDS indicates a nearly equal proportion of Ni and Zn, with an atomic ratio of Ni/Zn = 0.96. The specific capacitances of NiO is 295.5 Fg-1, ZnO is 117.3 Fg-1 and ZnO/NiO nanocomposites is 561.75 Fg-1 which are more than NiO and ZnO alone. This study shows that constructing binary oxide nanocomposites is an approach for developing high-performance supercapacitor electrode materials. Experimental observations on catalytic activity revealed that NiO/ZnO increased catalytic activity. Furthermore, adding NiO to ZnO in the composite increased the overall amount of oxygen vacancies in the samples. Our research lays the door for a simple, inexpensive, nontoxic, and quick technique to synthesize binary transition metal oxide-based electrode materials for high-performance supercapacitors.

RGO/ZnCo2O4 Composites as an Electrode Material for High-Performance Supercapacitor Application

Recently, composite material-based supercapacitors have attracted a lot of attention due to their enhancedperformance. In this work, we present a facile synthesis of RGO/ZnCo2O4 direct solution-based composites through a hydrothermal route anchored on nickel foam. ZnCo2O4 nanospheres wrapped under ribbon-like RGO nanosheets combine the synergistic properties of both in the form of hybrid electrode material. As a result, the RGO/ZnCo2O4 electrode exhibits a specific capacitance of 755.38 F/g at a scan rate of 5 mV/s with improved cyclic stability up to 2000 cycles. In addition to this, the hybrid electrode material also shows a good value for energy density and power density as 10.75 Wh/kg and 1500 W/kg at a current density of 1 A/g with 93.47% efficiency. This study thus signifies that the synergistic effect of both the electrodes in combination as a hybrid gives a better performance than the individual ones.

Exploiting the potential of mesoporous NiMoO4/TiS2 composite for enhanced electrochemical supercapacitor performance

The mesoporous electrode material offers a high surface area, excellent porous texture, and optimal pore-size distribution, facilitating increased active sites for ion accretion and enhanced ionic diffusion rates. NiMoO4, TiS2, and their composites such as NT-1, NT-2, NT-3, and NT-4 composites have been prepared by hydrothermal approach to enhance the capacitance of supercapacitor electrodes. Different methodologies have been employed to analyze the optical, morphological and structural characteristics of the synthesized materials. X-ray diffraction was utilized to assess the crystalline nature of both the pristine materials and composites. Scanning electron microscopy examination confirmed the formation of mesoporous and irregular nanoparticles with sizes ranging from 50 to 100 nm. Fourier-transform infrared spectroscopy was employed to examine the stretching vibrations of the prepared samples. Through photoluminescence (PL) analysis, the energy band gap of the NT-1 composite was decisive to be 2.78 eV. The NT-1 composite exhibits an impressive specific capacitance of 1257.14 Fg−1 at 1 Ag−1, attributed to its huge surface area, efficient charge transfer, and synergistic effect while demonstrating remarkable stability after 5000 cycles with 92% capacitance retention. Therefore, NT-1 binary metal sulfide composite unleashes high-performance supercapacitors with remarkable specific capacitance and cyclic stability.

High modulus carbon fiber based composite structural supercapacitors towards reducing internal resistance and improving multifunctional performance

Carbon fibers (CFs) based composite structural supercapacitors (CSSs) are promising multifunctional energy storage composites which can simultaneously realize load bearing and electricity storage. The device power is still low due to the high internal resistance of CSS. Herein, the CFs, electrolytes, monofunctional devices and multifunctional composite devices were investigated to show the attribution of the internal resistances. Both the normally used T300 CF and high modulus M55J CF fabrics were utilized. The electric in-plane and through-the-thickness resistances of CF fabric electrodes were characterized, respectively. The internal resistance of the monofunctional supercapacitor devices which were assembled using liquid electrolyte were evaluated considering the effects of CF sizing. The bicontinuous structural electrolytes (BSEs) composed of epoxy (EP) and ionic liquid (IL) were prepared as the multifunctional matrix of the CSSs. The chemical structure, thermal stability and ionic conductivity of the BSEs were assessed. The activated carbon (AC) loaded CFs and BSEs were used to fabricate the CSSs. Both the tensile and charge/discharge properties of the M55J CF CSSs were higher than those of the T300 CF CSSs. This work could provide new insights into the resistance attribution of CSS and how to simultaneously improve both mechanical and electrochemical performances of CSSs.

Activated carbon synthesized from Jack wood biochar for high performing biomass derived composite double layer supercapacitors

In this study, the electrochemical properties of bioderived activated carbon-based electrodes for supercapacitors formed using a sintered ceramic binder were investigated. Activated carbon derived from Jack wood tree (Artocarpus heterophyllus) with variable amounts of TiO2 nanoparticles as a binder, were used as electrodes in order to get good, activated carbon films on FTO substrates. No other binders were used in this study since most conventional binders devastate the electrical conductivity in the films. Furthermore, TiO2 has higher temperature tolerance compared to polymeric binders thus the electrode prepared can be used in wider applications. A series of electrochemical double-layer capacitors were fabricated and characterized by cyclic voltammetry and galvanostatic charge-discharge measurements. The supercapacitors prepared showed double-layer capacitive behavior. The electrodes that contain 90 % activated carbon and 10 % TiO2 show optimum performance along with an impressive specific capacitance of 147 F g−1 at 2 mV s−1 scan rate. This supercapacitor exhibits a power density of 68.5 W kg−1 while the energy density is 8.02 Wh kg−1. When the power density is as high as 1186.51 W kg−1 the energy density drops to 5.71 Wh kg−1. According to cyclic voltammetry measurements taken for 1000 cycles, the supercapacitor shows excellent cycle stability without any traces of capacitance drop.

Integration Device of Super-Capacitors with Dye-Sensitized Solar Cells

Integration Device of Super-Capacitors with Dye-Sensitized Solar Cells

Achieving enhanced multifunctional performance for structural composite supercapacitors by reinforcing interfaces with polymer coating

Carbon fiber structural composite supercapacitors possess the multifunctionality of storing electrochemical energy and withstanding mechanical loads simultaneously, attracting increased attention in electric vehicles, drones, and aircraft sectors. A polymer-based coating was meticulously constructed at the electrode/electrolyte interface to enhance adhesion and stability between active materials and the carbon fiber fabric collector under diverse conditions, especially mechanical stress. Mechanical testing and corresponding physical characterization substantiated the superior performance of the polymer coating. With the protective polymer coating, the optimized structural composite Zn-ion supercapacitor (SZSC), consisting of carbon fiber@active carbon-P (CF@AC-P) cathode, ionogel electrolyte, and Zn anode, displayed a maximum energy density of 164.6 mWh kg−1, at power density of 563.3 mW kg−1. Moreover, the optimized SZSC demonstrated stable operation over more than 8000 cycles at 0.3 mA cm−2 without capacity degradation. The optimized SZSC exhibited a tensile strength of 399.7 MPa and Young's modulus of 11.5 GPa. Furthermore, employing vacuum infusion techniques, the fabricated three-dimensional (3D) wing skin model shell and tube shell curved-surface structural composite Zn-ion supercapacitor component composites showcased exceptional electrochemical performance. These achievements further validate the practicality of 3D multifunctional composites. Consequently, this research presented a practical and straightforward interface engineering approach to develop multifunctional structural devices with remarkable electrochemical and mechanical properties.

Current collectors of carbon fiber reinforced polymer for stackable energy storage composites

Energy storage structural composites combine the function of storing energy with that of bearing mechanical load. Electrode and electrolyte components can simply be laminated to fabricate composite energy devices. We advance here a sheet of carbon fiber fabric interlaced with epoxy resin as a bipolar current collector (CC), which becomes a component of bipolar electrode when coated with an active material and dried. The CC is quite light and its specific strength is an order of magnitude higher than the typical metal CCs. We also advance a sheet of glass fiber fabric, a separator, impregnated with a eutectogel electrolyte as a composite separator/electrolyte component. The ionic conductivity of the electrolyte is excellent over a wide range of temperature and is stable up to 100 °C. Composite supercapacitors are fabricated by alternate stacking of the two component sheets. They are used to verify the scalability of the energy device achievable by the simple lamination and to demonstrate the significant enhancement in the power and energy density attainable by reducing the device weight through the utilization of the bipolar CCs. Practical utility of the stacked supercapacitors is demonstrated.

MXene/PANI composite fiber-based asymmetric supercapacitors for self-powered energy storage system

Fiber-shaped supercapacitors (FSSCs) have attracted tremendous attention for their various potential applications in portable and wearable electronics. However, the low energy density of FSSCs hinders their wide applications in wearable electronics. Herein, we develop an in-situ chemical polymerization method to construct MXene/polyaniline-based asymmetric FSSCs, which delivers an excellent electrochemical performance, including excellent rate capability, high area specific capacitance (510 mF cm−2) and energy density (15.71 μWh cm−2). This work provides a new strategy for fabricating high-performance flexible supercapacitors and paves the way for the development of wearable energy storage devices.

A robust approach for designing a quaternary hybrid (NiMn2O4/NiWO4/NGO/PANI) as novel electrode material with enhanced stability for supercapacitor applications

The urge for energy storage and the advancement of state-of-the-art supercapacitor technology necessitates the exploration of robust electrodes with superb specific capacitance (Cs) and excellent cyclic life. In this perspective, an anomalous quaternary hybrid material (NiMn2O4/NiWO4/NGO/PANI) is synthesized through polymerization of aniline in the presence of a ternary hybrid (NiMn2O4/NiWO4/NGO), while the ternary (NiMn2O4/NiWO4/NGO), binary (NiMn2O4/NiWO4), and pristine (NiMn2O4 and NiWO4) materials are synthesized by hydrothermal route. The electrochemical performance as well as the physiochemical peculiarities of all the hybrids and pristine materials are analyzed. Electrochemical experimentation reveals that among all prepared electrodes, the quaternary electrode (NiMn2O4/NiWO4/NGO/PANI) possesses remarkable Cs = 636 F/g at 2 mV/s, with minimum ohmic (0.6125 Ω) and charge transfer (0.357 Ω) resistances. Moreover, the proposed quaternary electrode exhibits Cs = 682 F/g at 0.5 A/g with superior energy density (28.68 Wh/kg at 0.5 A/g), power density (5499.92 W/kg at 20 A/g), and 94.11 % capacitive retention over continuous 10,000 charge/discharge cycles at 30 A/g, through GCD experiment. Optimized composition, morphology, mesoporosity, and quasi-crystalline nature of NiMn2O4/NiWO4/NGO/PANI recommend the novel quaternary hybrid as a distinctive electrode for composite hybrid-type supercapacitor applications.

A flexible composite film electrode and supercapacitor based on combined effect between graphene oxide and graphene

Graphene film has drawn great attention in flexible supercapacitors for its large specific surface area and high conductivity, but the trade-off between capacitance (positively correlated with structural defects) and electrical conductivity (negatively correlated with structural defects) still hinder its application. Herein, a graphene-based composite film is fabricated by cooperating graphene oxide with highly conductive graphene flakes. With the combined effect, graphene flakes endow the composite films with high electrical conductivity, while graphene oxide provides extra pseudocapacitance. The composite film shows a high specific capacitance of 191.1 F g−1, which is far beyond that of pure graphene film (6.7 F g−1). The assembled flexible supercapacitor shows no capacitance decline when bent at different angles, and the capacitance retention of the supercapacitor keeps at 55.8% after 4500 bending-releasing cycles (0–180°). The excellent mechanical and electrochemical performance of reduced graphene oxide/graphene composite film makes it a promising candidate in flexible supercapacitors.

Sulfonated hypercrosslinked polymer enhanced structural composite supercapacitors

Structural supercapacitors are multifunctional devices able to bear mechanical load while storing electrical energy. Carbon fibres can be used as a bifunctional component within structural supercapacitors, acting both as current collector and mechanical reinforcement. A promising route to such devices is to increase the surface area of carbon fibres, which can be achieved by the deposition of active materials, and embed them into a structural electrolyte. A highly sulfonated, high porosity hypercrosslinked polymer was deposited onto carbon fibres by electrophoretic deposition from an aqueous suspension. We investigated the effect of polymer and binder concentration in the deposition suspension on the electrochemical properties of the coated carbon fibre electrodes. Multifunctional structural composite supercapacitors had a fibre volume fraction of only 21% and possessed a tensile strength and Young's modulus of 495 MPa and 49 GPa, respectively. A specific capacitance of 1.2 F/g was reached, comparable to graphene coated carbon fibre electrodes. At room temperature and ambient humidity an energy density of 39 mWh/kg and a power density of 15 W/kg were measured. We demonstrate that moisture plays a major role in the energy storage mechanism in these SCs.

Symmetrical Composite Supercapacitor Based on Activated Carbon and Cobalt Nanoparticles with High Cyclic Stability and Current Load

Supercapacitors play an important role in a future clean-energy landscape to meet the challenges of existing energy-storage/delivery systems. They suffer from low energy density and are mainly used for the storage/delivery of electrical energy in high power demands. However, improvement of their energy density is vital to develop energy storage systems that can respond to the energy demands of emerging technologies requiring a wider energy/power spectrum. In this article, a symmetrical capacitor is developed from a composite consisting of synthesized activated carbon and cobalt oxide to improve the energy storage performance of the supercapacitor. Uniform distribution and immobilization of cobalt nanoparticles within the composite is achieved by embedding cobalt acetate into the initial resorcinol formaldehyde polymeric aerogels, followed by the pyrolysis of the gel in Ar atmosphere and activation of the carbon in CO2 atmosphere at 800 °C. The activated carbon/cobalt composite is used as the electroactive material in electrode formulation. The electrochemical characteristics of the synthesized electrode materials demonstrates an optimized specific capacitance of 235 F g−1 at a sweep rate of 10 mV s−1 in a three-electrode system. The symmetrical capacitor has a capacitance of 66 F g−1 at 1 A g−1, a very high rate of performance in 10,000 cycle tests, and a rate capability of 24% at 30 A g−1. The capacitor shows a power density of up to 15 Wh k g−1. The presence of cobalt spices makes it possible to optimize the capacitance of a symmetrical capacitor, while the capacitance of a symmetrical activated carbon capacitor cannot be optimized.

Study on the Application of Nitrogen-Doped Holey Graphene in Supercapacitors with Organic Electrolyte.

We present a facile low-cost method to produce nitrogen-doped holey graphene (N-HGE) and its application to supercapacitors. A composite of N-HGE and activated carbon (AC) was used as the electrode active material in organic-electrolyte supercapacitors, and the performances were evaluated. Melamine was mixed into graphite oxide (GO) as the N source, and an ultra-rapid heating method was used to create numerous holes during the reduction process of GO. X-ray photoelectron spectra confirmed the successful doping with 2.9-4.5 at.% of nitrogen on all samples. Scanning electron micrographs and Raman spectra revealed that a higher heating rate resulted in more holes and defects on the reduced graphene sheets. An extra annealing step at 1000 °C for 1 h was carried out to further eliminate residual oxygen functional groups, which are undesirable in the organic electrolyte system. Compared to the low-heating-rate counterpart (N-GE-15), N-HGE boosted the specific capacity of the supercapacitor by 42 and 22% at current densities of 0.5 and 20 A/g, respectively. The effects of annealing time (0.5, 1, and 2 h) at 1000 °C were also studied. Longer annealing time resulted in higher capacitance values at all current densities due to the minimized oxygen content. Volumetric specific capacitances of 49 and 24 F/cm3 were achieved at current densities of 0.5 and 20 A/g, respectively. For the high-power-density operation at 31,000 W/kg (or 10,000 W/L), an energy density as high as 11 Wh/kg (or 3.5 Wh/L) was achieved. The results indicated that N-HGE not only improved the conductivity of the composite supercapacitors but also accelerated ion transport by way of shortened diffusion paths through the numerous holes all over the graphene sheets.

A composite structural supercapacitor based on Ni–Co-layered double hydroxide–coated carbon cloth electrodes

Composite structural supercapacitors (CSSs) are valuable for their use in structural optimization because they can provide energy storage capacity while bearing mechanical loads, thereby enabling weight and volume reduction. Herein, flexible energy storage devices are embedded into carbon fiber reinforced polymer (CFRP) to form a CSS. In the flexible device, a positive electrode (carbon cloth coated with Ni–Co-layered hydroxide, NiCo-LDH@CC), a negative electrode (activated carbon–coated carbon cloth, AC@CC), and a separator (glass fabric) are bonded together by PVA-KOH gel electrolyte. The CSS (5:5 NiCo-LDH-CSS) provides competitive electrochemical properties (specific capacitance of 610 mF g−1, energy density of 191 mWh kg−1, and power density of 1,508 mW kg−1) and good mechanical properties (flexural strength of 495 MPa and flexural modulus of 125 GPa). The study conducts a systematic analysis of capacity decay during the electrochemical cycling process of 5:5 NiCo-LDH-CSS. In-situ mechano-electrochemical tests are also performed to verify the stable electrochemical behavior under external dynamic and static loads, which is a rarely studied aspect in other reports. This investigation provides assurance for the safety and reliability of future CSS applications. The study findings suggest that the 5:5 NiCo-LDH-CSS possesses good multifunctionality, and can provide a new idea for further development in CSSs.

Novel approach to utilise highly conductive but electrochemically unstable current collector materials in textile supercapacitor electrodes

Metal-based materials, such as silver or copper, are highly desired as current collector materials for flexible energy storage due to their excellent electrical properties but lack the long-term operational electrochemical stability. Herein we report a method to prevent the corrosion of such materials, while fully exploiting their electrical properties. This was achieved by covering the current collector with an electrochemically stable conductive carbon-based layer. The barrier layer allows the flow of charge between the electrically conductive elements of the textile composite electrodes, while protecting the current collector from contacting the electrolyte. The areal power and energy densities obtained after 1000 bending cycles were 29.88 and 0.01 mWh cm−2, respectively, with no evident degradation. Additionally, patterned current collectors were designed to deposit lower quantities of ink, without detriment to electrochemical performance. After 1000 bending cycles, the textile composite supercapacitors (TCSs) having 50% less current collector material demonstrated an areal power and energy density of 28.08 and 0.01 mWh cm−2, respectively. The proposed strategy is essential in enabling the utilisation of highly conductive metal-based inks, improving the rate capabilities and long-term operation of wearable energy storage devices, while maximising specific power and energy densities of TCSs, and decreasing the manufacturing cost.

Core@shell nanorods for enhancing supercapacitor performance: ZnWO4 nanorods decorated with colloidal SnO2 quantum dots

In this study, a novel composite supercapacitor electrode material, ZnWO4 nanorods decorated with colloidal SnO2 quantum dots, was synthesized via a facile sonochemical method. The synthesized material was systematically characterized to confirm the successful construction of core@shell nanorods. SnO2 surface encapsulation on ZnWO4 nanorods improves electrochemical performance by enhancing conductivity and adding storage sites. ZnWO4 nanorods@colloidal SnO2 quantum dots, displayed an electrochemical performance of 162 F/g specific capacitance, 98% capacity retention after 5000 cycles.

Flexible Hf6Ta2O17@ acidified carbon nanotube composite films with enhanced interfacial interaction for high-performance supercapacitors

Recently, various transition metal oxides (TMOs) have been introduced to modify carbon nanotubes (CNTs), demonstrating great potential for high energy storage performance. Herein, we designed a novel flexible composite film based on Hf6Ta2O17 (HTO) and CNTs to leverage their complementary advantages. HTO nanocrystals were prepared by the polymer derived ceramics (PDC) method, which could be uniformly distributed and firmly embedded on the surface of carboxy functionalized single-wall carbon nanotubes (SWCNTs). More importantly, we developed a new way to enhance the interfacial interaction between the TMOs and the carbon materials to optimize the energy storage performance of the resulting composites. Finally, the composite supercapacitor showed the maximum specific capacitance of 5862.5 mF cm−2 at the current density of 5 mA cm−2 with a potential window of 2 V, which was much higher than those obtained from the two materials alone. Furthermore, the synergistic effect was confirmed to efficiently reduce the work function of the composite as well as the energy required by the electronic transition. Our results implied that the composite materials based on TMO and carbon materials (e.g. nanotubes or graphene), including the flexible HTO@ acidified carbon nanotube composite film, holds real promise for the applications as promising energy storage materials.

Energy Storage Performance of Environmentally Friendly Lotus Petiole–Porous Carbon Composites

Waste management is essential to achieve sustainable development and protect the environment. Herein, a strategy was tested to utilize large volumes of lotus petiole waste. In this work, a composite supercapacitor electrode of lotus petiole with a porous structure and MoO2 with an ice flower structure was fabricated via an in situ hydrothermal growth method. The prepared PC-50 lotus petiole–porous carbon material exhibited a unique hierarchical porous structure and a high specific surface area (1887 m2 g–1). The composite electrode exhibits high reversible capacity (515.10 mAh g–1 at 2 A g–1) in the three-electrode system. The maximum gravimetric energy density reached 30.10 W h kg–1 at a power density of 387 W kg–1, and a favorable energy density of 20.19 W h kg–1 was retained even at a high power density of 3.69 kW kg–1 in the symmetric device. Moreover, the symmetric device shows superior cycling stability (91.60% capacity retention in 2000 cycles). Electrochemical impedance spectroscopy was used to study the electrochemical interface characteristics and verify the electrochemical performance of the composite electrodes. The research results provide guidance for the design of high-performance metal oxide–biomass carbon composites and the comprehensive utilization of waste biomass.

Preparation and electrochemical properties of thieno-[3,4-b] pyrazine conjugated polymer composite supercapacitor carbon powder electrode materials for Li-organic battery

In this work, two D-A monomers 2,3-di(5-methylfuran-2-yl)-5,7-di(thiophene-2-yl) thiopheno[3,4-b] pyrazine (MFTTP) and 2,3-di(5-methylfuran-2-yl)-5,7-di(4-methoxythiophen-2-yl) thiopheno [3,4-b] pyrazine (MFMOTTP) were first obtained by Stille Coupling reaction, and then the corresponding composites were obtained by in-situ oxidative polymerization method with supercapacitor carbon. The surface morphology, chemical structure, and the element valence states of two materials were characterized by scanning electron microscopy, infrared and XPS, respectively. The specific surface areas of PMFTTP@SC and PMFMOTTP@SC are measured as 756.5 and 954.9 m2/g, respectively. The CV curves were used to determine the initial oxidative and initial reduction potentials, both polymers have a narrow band gap with Eg values below 1.5 eV, electron clouds in the HOMO and LUMO orbits of the polymer are mainly distributed on the aromatic rings of the polymer backbone. Polymer composite materials were used as the anode materials and the lithium sheets were used as counter electrode, and then lithium ion batteries are assembled. The first discharge specific capacities of PMFTTP@SC and PMFMOTTP@SC are 741.9 and 951.3 mAh/g at a current density of 100 mA/g, and as the electrodes are activated in the subsequent cycles, their coulomb efficiencies can reach more than 92% from the third cycle. In contrast, PMFMOTTP with methoxy-thiophene as the donor unit has higher conductivity and lower corresponding impedance due to its stronger electron donating ability and abundant pore structure, which is also more conducive to the lithiation/delithiation redox process.