High-performance Supercapacitor Applications Research Articles

NiCo-MOF directed NiCoP and coconut shell derived porous carbon as high-performance supercapacitor electrodes

Bimetallic mickel/cobalt metal-organic frameworks(MOFs) have showed important applications as supercapacitor electrode materials due to their rich redox active sites, regular pore structure and huge specific surface area. But their specific energy and capacitance are limited. In this paper, a MOFs phosphorization strategy was proposed for preparing high-performance NiCo bimetallic phosphide nanosheets (NiCoP) by simple OH− ion etching and phosphorization. The formed nanosheet structure possesses a huge specific surface area, which is beneficial for the Faraday reaction. The as-prepared Ni1Co1-10P nanosheets present significant synergy among transition metal ions, which contributes to enhanced electrochemical performance. Because of structural and composition advantages, the optimized Ni1Co1-10P nanosheets show a superior specific capacitance (1188.4 F g−1 at 1 A g−1) than corresponding hydroxide (Ni1Co1-OH) and Ni1Co1-MOF precursors. The as-assembled asymmetric supercapacitor (ASC) using Ni1Co1-10P nanomaterial as the positive electrode and coconut shell derived porous carbon (EC) with huge surface area and electric double layer capacitor (EDLC) property as negative electrode delivers a high specific capacitance of 135.5 F g−1 at 1 A g−1 and a maximum energy density of 55.01 Wh kg−1 at 849.94 W kg−1 as well as excellent capacitance retention (86.12 % after 10,000 cycles). Therefore, the prepared Ni1Co1-10P electrode materials have a broad application in high-performance supercapacitors.

One-Pot Synthesis of MnO2/Reduced Graphene Oxide Via Hydrothermal Routes for Supercapacitor Applications

Manganese dioxide (MnO2) is a promising supercapacitor electrode material due to its high theoretical capacitance, low cost and environmental compatibility. However, the electrochemical performance of MnO2 is often limited by low electrical conductivity of MnO2. The MnO2/carbon composites have been successfully demonstrated as an effective way to improve overall electrical conductivity of MnO2 based materials.In this study, we report MnO2/reduced graphene oxide (rGO) composites for high performance supercapacitor applications. The MnO2/rGO composites exhibited 381F/g at a charge/discharge current density of 5 A/g, which was significantly higher as compared to that of pure MnO2 (140 F/g at a charge/discharge current density of 5 A/g). This result indicates that improved capacitance of the MnO2/rGO composites benefited from the incorporated rGO properties, such as high electrical conductivity and large surface area.

In-situ synthesis of mixed-phase carbon material using simple pyrolysis method for high-performance supercapacitor

We report a novel mixed phase carbon material that contains both amorphous as well as crystalline phases for supercapacitor application. The amorphous carbon and crystalline carbon nanotubes are present in this mixed phase material which is prepared using an in-situ process in a simple and cost-effective method. In supercapacitor devices, better performance is achievable when there is good surface accessibility in electrode material and decent ion mobility. Amorphous material provides good surface accessibility whereas crystalline offer better electrons and ions mobility. Hence, the prepared mixed-phase carbon material has advantages for the supercapacitor. The material is tested for supercapacitor application where the electrochemical performances are obtained using Cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) and Electrochemical impedance spectroscopy (EIS) measurements. The mixed-phase electrode results in a specific capacitance of 37.54 F g−1 at 1 A g−1 and 36.80 F g−1 at 5 mV/s. The storage performance of this material is further increased by integrating it with a few layers of graphene. The prepared composite with a 30 wt. percentage of few-layer graphene gives the better supercapacitive properties and the maximum capacitance achieved by the composite is 282.52 F g−1 at 1 A g−1 and 281.84 F g−1 at 5 mV/s. The fabricated mixed-phase composite (30 wt% of few-layer graphene) offers excellent cyclic stability and 93 % capacitance is retained even after 10,000 cycles at 1 A g−1. These outcomes suggest the mixed-phase composite electrode could be the best choice for high performance supercapacitor applications.

Facile hydrothermal synthesis of ZnFe2O4 nanostructures for high-performance supercapacitor application

Nowadays, binary transition metal oxides have attracted wide attention as an electrode material for supercapacitor applications. In this respect, we report a facile and cost-effective hydrothermal route for the synthesis of ZnFe2O4 nanostructures on nickel foam using a binder-free approach. The as-synthesized ZnFe2O4 nanostructures were characterised to study the structural, morphological and electrochemical properties. When utilized as an electrode for supercapacitor, ZnFe2O4 delivered superior specific capacitance of 552 F/g at a scan rate of 5 mV/s with a long term cyclic stability for 1000 cycles. This excellent electrochemical performance ZnFe2O4 electrode material suggests its potential use for next-generation supercapacitors.

Titanium dioxide nanobelts modified with manganese dioxide nanoflakes for high-performance supercapacitor applications

Titanium dioxide nanobelts modified with manganese dioxide nanoflakes for high-performance supercapacitor applications

Enhanced electrochemical properties of zinc and manganese co-doped NiO nanostructures for its high-performance supercapacitor applications

In electrochemical energy storage devices, improving the availability of ions in the electrodes for charge storage and rate performance is a challenging task in the present era. So, in this report, an attempt was made to prepare Zn and Mn co-doped NiO nanostructures with improved electrochemical performance. The structural study revealed pure, and co-doped NiO nanostructures crystallize into face-centred cubic geometry with space group Fm3m. A prominent decrease in grain size was noticed with the increase in Mn concentration, showing an inverse relation with the optical bandgap. The room temperature ferromagnetism was improved by Mn doping. The electrochemical study proves the pseudocapacitive nature, with enhanced specific capacitance (846.71 Fg−1) in Ni0.9Zn0.04Mn0.06O nanoparticles. The galvanostatic charge–discharge study revealed a power density of 8900 W/kg at an energy density of 12.47 Wh/kg in Ni0.9Zn0.04Mn0.06O nanostructures. The improved specific capacitance, fascinating charging-discharging ability, and high-power density of Ni0.9Zn0.04Mn0.06O nanostructures makes it a special candidate for high-performance supercapacitor.

Preparation of three-dimensional Co3O4@NiMoO4 nanorods as electrode materials for supercapacitors

Co3O4@NiMoO4 composite electrode material with Co3O4 nanowire as precursor has been successfully prepared by hydrothermal method and treatment of thermal annealing. The results of this work show the phase characterization, morphology characterization and electrochemical testing. At the current density of 1 mA/cm2, the specific capacitance of the Co3O4@NiMoO4 electrode material is 3940 mF/cm2 and exceptional cycling stability is 84% after 10000 cycles. Furthermore, the Co3O4@NiMoO4//AC device demonstrates an outstanding energy density of 102.52 mWh/cm3 at power density of 2703.82 mW/cm3 and outstanding long-term cycling stability of 78.2% after 12000 cycles. These remarkable results indicate that the unique Co3O4@NiMoO4 nanorod structure is a promising cathode electrode material in high-performance supercapacitors applications.

Synergistic effect of La2o3 -Nio nanocomposite based electrode for electrochemical high-performance asymmetric supercapacitor applications

Global economic growth and rapid industrial development have resulted in a severe energy problem. Renewable energy sources have been replaced by alternative and sustainable energy sources. Super capacitors are one of the most important types of energy storage devices. The development of supercapacitor electrodes with maximum performance is currently the most important research topic in this area. Here we present the results of hydrothermal research on rare earth-based nanocomposites of Lanthanum-Nickel La2O3 -NiO-based electrodes for electrochemical super capacitor applications. XRD, FTIR, TG/DTA, SEM, TEM and EDAX techniques are used to examine the physico-chemical characteristics such as crystallographic structure, vibrational characteristics, thermal stability morphology, chemical composition, and its features respectively. According to the cyclic voltammetry (CV) investigation, the prepared nanocomposite materials have a Specific capacitance of 704 F/g at scan rate of 5 mV/s. EIS analysis demonstrates the RsValues ofLa2O3 (0.11549 Ω) NiO(0.1937 Ω) La2O3 -NiO(0.641 Ω) increased conductivity of nanocomposite material. According to galvanostatic charge–discharge (GCD) tests, the La2O3 -NiO electrode has a maximum specific capacitance of 564 F/g at 1 A/g current density in 1 M KOH electrolyte. This result proved that the prepared (La2O3 -NiO Nanocomposite), electrode material used for practical application, which shows good capacitive retention of 93.4%even after 2000 cycles. More ever asymmetric device constructed superior cyclic stability of 77.2%of capacitive retention even after 2000 charge discharge cycle.

Low temperature thermally reduced graphene oxide directly on Ni-Foam using atmospheric pressure-chemical vapour deposition for high performance supercapacitor application

A binder free approach was use to prepare thermally reduced graphene oxide (TRGO) at 200 °C directly on Ni-Foam (NF) (current collector) via atmospheric pressure-chemical vapour deposition (AP-CVD) and used as a positive electrode for supercapacitor application. The TRGO/NF electrode preparation method is simpler, quicker, cheaper and more effective compared to other method. The half-cell electrochemical performances in 6 M KOH showed a maximum specific capacity of 52.64 mA h g−1 at 0.5 A g−1. The device: TRGO/NF//PAC showed a specific energy and power of 18.72 Wh kg−1 and 547.52 W kg−1 respectively at 1 A g−1; and 14.10 Wh kg−1 and 2.5 kW kg−1 respectively at 5 A g−1. The high coulombic efficiency (99.9%) and capacitance retention (70%) indicate outstanding stability. These results represent a significant progress in the fabrication of binder and conductive enhancement free positive electrode for electrochemical energy storage devices.

Electrodeposition of CoxNiVyOz Ternary Nanopetals on Bare and rGO-Coated Nickel Foam for High-Performance Supercapacitor Application.

We report a simple strategy to grow a novel cobalt nickel vanadium oxide (CoxNiVyOz) nanocomposite on bare and reduced-graphene-oxide (rGO)-coated nickel foam (Ni foam) substrates. In this way, the synthesized graphene oxide is coated on Ni foam, and reduced electrochemically with a negative voltage to prepare a more conductive rGO-coated Ni foam substrate. The fabricated electrodes were characterized with a field-emission scanning electron microscope (FESEM), energy-dispersive X-ray spectra (EDX), X-ray photoelectron spectra (XPS), and Fourier-transform infrared (FTIR) spectra. The electrochemical performance of these CoxNiVyOz-based electrode materials deposited on rGO-coated Ni foam substrate exhibited superior specific capacitance 701.08 F/g, which is more than twice that of a sample coated on bare Ni foam (300.31 F/g) under the same experimental conditions at current density 2 A/g. Our work highlights the effect of covering the Ni foam surface with a rGO film to expedite the specific capacity of the supercapacitors. Despite the slightly decreased stability of a CoxNiVyOz-based electrode coated on a Ni foam@rGO substrate, the facile synthesis, large specific capacitance, and preservation of 92% of the initial capacitance, even after running 5500 cyclic voltammetric (CV) scans, indicate that the CoxNiVyOz-based electrode is a promising candidate for high-performance energy-storage devices.

Novel synthesis of layeredMoS2/TiO2/CNTnanocomposite as a potential electrode for high performance supercapacitor applications

This work is aimed to synthesize hybrid nanocomposite electrode materials for supercapacitor applications. The carbon nanotubes (CNTs) are incorporated into MoS2 as well as TiO2 to form different hybrid electrode materials such as MoS2/CNTs, TiO2/CNTs, and MoS2/TiO2/CNTs in an effort to improve the electrochemical performance. The resulting hybrid electrode materials are examined by SEM, TEM, XRD, XPS, and Raman studies. Cyclic voltammetry and galvanostatic charge-discharge tests are used to evaluate the specific capacitance and charge-discharge stability of the synthesized MoS2/TiO2/CNTs. Among the hybrid electrode materials investigated, the MoS2/TiO2/CNTs exhibits superior electrochemical performance with specific capacitance of 1252.57 mA h/g at a scan rate 20 mV/s as compared with MoS2/CNTs (810.53 mA h/g), TiO2/CNTs (607.10 mA h/g), and CNTs (204.35 mA h/g). All electrochemical tests were carried out in a solution of 1 M KOH. The Rct and Rf for the MoS2/TiO2/CNTs electrode were found to be 1.7 Ω.cm2 and 2.1 Ω.cm2, respectively, which were significantly lower than the corresponding Rct (40.2 Ω.cm2) and Rf (51.1 Ω.cm2) for the CNTs electrode, indicating that the MoS2/TiO2/CNTs has a significantly lower overall impedance, which could be one of the key factors responsible for the improved electrochemical performance of the MoS2/TiO2/CNTs. Moreover, this MoS2/TiO2/CNTs hybrid electrode displays good cycling stability with the capacitance retention of 98.83% after 10 000 cycles of charge-discharge at 1 A/g. The energy density and power density of MoS2/TiO2/CNTs composites are found to be 757.80 Wh/kg and 4546.80 W/kg respectively.

Embedding NiS nanoflakes in electrospun carbon fibers containing NiS nanoparticles for hybrid supercapacitors

Carbon fibers consistently suffer from low specific capacitance due to underutilized structure, severely hindering their application in high-performance supercapacitors. In this work, a novel and scalable “inner-outer synergistic strategy” is developed for superior electrode materials via embedding NiS nanoflakes in electrospun carbon fibers containing NiS nanoparticles (NiSNF/CF@NiSNP). Uniformly sized NiS nanoparticles are encapsulated in the inner region of the carbon fibers as redox active agent, which impart additional Faraday capacitance to the electrode while efficiently avoiding the aggregation of the nanoparticles. Simultaneously, the evenly distributed NiS nanoflakes firmly immobilized on the outer surface of the carbon fibers by the impregnating-sulfurization procedure significantly expand the accessible area of ions and alleviate the volume expansion by preventing stacking. Profiting from the felicitous designed architecture, the NiSNF/CF@NiSNP-3 electrode delivers a reversible specific capacitance of 1691.1F g−1 at 1 A g−1 and remarkable coulombic efficiency of 98.5 %. Furthermore, the hybrid supercapacitor demonstrates a maximum energy density of 31.2 Wh kg−1 and a power density of 4004.3 W kg−1 along with impressive cycling durability of 87.8 % retention for up to 5000 cycles. This demonstrated “inner-outer simultaneous exploitation” engineering provides an appealing and instructive insight for enhanced electrochemical performance of fibrous materials, and can be extended to a variety of energy material systems.

Construction of Cu-Doped Ni–Co-Based Electrodes for High-Performance Supercapacitor Applications

Construction of Cu-Doped Ni–Co-Based Electrodes for High-Performance Supercapacitor Applications

Nitrogen-Doped High Surface Area Porous Carbon Material Derived from Biomass and Ionic Liquid for High-Performance Supercapacitors

In this work, bioderived high surface area, porous activated carbons (ACs) are synthesized from dried Sterculia foetida (SF) fruit shells via KOH activation. Further, for high-performance supercapacitor (SC) application, the nitrogen-doped AC (NAC) has been derived by pyrolysis of a nitrogen-enriched ionic liquid (IL) and AC mixture. Herein, aprotic 1-ethyl-3-methyl-imidazolium dicyanamide ([EMIM][DCN]) IL is used as a nitrogen precursor. A series of NACs has been successfully developed by tuning the weight ratio of IL and AC. The optimized NAC (2:1) exhibits suitable graphitization degree, hierarchical micromesopores to ensure effective electrolyte diffusion, high surface area, and enhanced wettability. Further, in a three-electrode configuration, the NAC (2:1) electrode shows a high specific capacitance of 567 F g–1 at 0.5 A g–1. Moreover, a symmetric two-electrode SC device was constructed, providing excellent specific energy of 13 Wh kg–1 at 300 W kg–1. Overall, this study presents the positive aspects of an IL as a nitrogen precursor to synthesize high surface area NACs as a promising electrode material for SC applications.

Flower-like nickel hydroxide@tea leaf-derived biochar composite for high-performance supercapacitor application

Renewable and sustainable high-performance energy storage devices are desirable to fulfill the demands of next-generation power sources. In this study, we report a flower-like nickel hydroxide/spent tea leaf-derived biochar (NiNF@TBC) composite for high-performance supercapacitor application. The tea leaf-derived biochar (TBC) with a specific surface area of 1340 m2 g−1 is used as the Ni(OH)2 support to fabricate NiNF@TBC composites. The highly porous and hierarchical structure of the as-synthesized NiNF@TBC composite facilitates the electrolyte ion and electron diffusion and transport more readily. As a result, the decrease in diffusion path and the increase in conductivity of NiNF@TBC for energy storage applications. The NiNF@TBC electrode shows excellent electrochemical properties with a specific capacitance of 945 F g−1 at 1 A g−1 in a three-electrode cell and high stability of 95% after 10,000 cycles. Moreover, the symmetric supercapacitor fabricated with NiNF@TBC delivers a specific capacitance of 163 F g−1 in 1 M Na2SO4 solution. The Ragone plot of the symmetric device exhibits energy density in the range of 19 – 58 Wh kg−1 with power density in the scale of 826 – 6321 W kg−1. An excellent long-term cyclic stability of 94% is obtained after 10,000 charge–discharge cycles. Such an excellent performance has demonstrated the feasibility of utilizing agricultural wastes as green carbon sources, which can combine with various metal hydroxides to produce hybrid nanomaterials as a highly potential electrode material for green sustainable supercapacitor applications.

Structure control of heteroatoms’ self-doped porous carbon materials derived from cyclomatrix polyphosphazene for high-performance supercapacitor application

Structure control of heteroatoms’ self-doped porous carbon materials derived from cyclomatrix polyphosphazene for high-performance supercapacitor application

Synthesis and characterization of mixed ternary transition metal ferrite nanoparticles comprising cobalt, copper and binary cobalt–copper for high-performance supercapacitor applications

Metal ferrites have outstanding electrochemical characteristics owing to the numerous oxidation states of the metal ions, making them promising materials for addressing both sustainable energy conversion and storage and growing environmental issues. Therefore, three nanocrystallites transition metal ferrites, CoFe2O4, CuFe2O4 and Co/CuFe2O4, were synthesized using citrate precursors and used as electrode materials for supercapacitor applications. Mixed transition metal ferrite nanoparticles were characterized by Fourier transform infrared (FT-IR), scanning electron microscope (SEM) complemented with energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), Raman spectroscopy and thermal analysis (TGA). The findings illustrated the formation of a single-phase spinel ferrite as proved from XRD data. In addition, the particle shape and particle size obtained from TEM analysis revealed that the as-synthesised nanomaterial exhibited spherical shape with a size ranging from 30 to 50 nm. The result demonstrated that while using a three-electrode configuration, the electrochemical performance of the ferrite nanoparticles achieved a remarkable maximum specific capacitance of 893 Fg−1 at a scan rate of 5 mV s−1. At a current density of 1 Ag−1, Co–Cu ferrite exhibited outstanding cycling stability for 3000 cycles with 90% capacity retention. Based on the aforementioned data, it can be considered that the remarkable electrochemical performance of the Co–Cu ferrite nanocomposites can be considered as promising materials to be used for supercapacitor electrodes.

Electrodeposited Bi(OH)3@Mo(OH)4 nanostructured electrode for high-performance supercapacitor application

Energy storage devices play a vital role in the current modern world to fulfill the needs of high-power triggered electronic appliances. Supercapacitors are emerging devices with the potential to lead the energy storage era. Herein, Bi(OH)3@Mo(OH)4 nanostructured active materials were coated on nickel foam electrodes using a versatile electrochemical deposition technique for high-performance supercapacitor applications. Through the synergistic effect of the elements of Bi and Mo, the nanostructured morphology, charge transfer capability, capacitor performance, and rate capability of the developed capacitor were significantly improved compared to those of Bi(OH)3 and Mo(OH)4 electrodes. The active electrodes exhibited a high areal specific capacitance of 759.5 mF/cm2 at a current density of 1 mA/cm2 in 1 M KOH electrolyte. At scan rates exceeding 3 mV/s, the surface-controlled process contributed more than 60% capacity. Nyquist plots were obtained, and stability of the electrodes was also conducted. The electrodes demonstrated excellent charge transfer capabilities and cycling stability with 82.6% capacitance retention at a current density of 10 mA/cm2 for 3,000 cycles. Hence, Bi(OH)3@Mo(OH)4 nanostructured active materials are potential candidates for high-performance supercapacitors.

Synthesis of Micron-Sized NiAl/NiCoAl-Layered Double Hydroxides via a Facile Double Hydrolysis Dropping Method for Supercapacitor Applications

The transition metal-based layered double hydroxides (LDHs) for high-performance supercapacitor applications were synthesized by the double hydrolysis dropping method. We found that the dropping sequence of the cation and anion solutions has a strong influence on the microstructural and electrochemical properties of LDHs. The NiAl LDHs obtained by dropping the Ni2+ solution into the AlO2- solution have obvious layered structures with a particle size of the order of micrometers. They are different from those LDHs prepared by the conventional double hydrolysis method and hydrothermal method. The specific capacity of the NiAl LDHs is about 615 C g−1 at 0.5 A g−1, which is almost twice that of the sample synthesized by the traditional double hydrolysis method (339 C g−1). It is indicated that the performance of the NiAl LDHs is improved by the dropping method. Moreover, an excellent cyclic stability of 83.3% capacitance retention after 1000 cycles at 3 A g−1 was achieved. In addition, the trimetallic NiCoAl LDHs have been synthesized successfully by the dropping method. The results showed that the addition of Co effectively enhanced the electrochemical properties of LDHs. The optimal NiCoAl LDHs display an excellent specific capacity of 990 C g−1 at 0.5 A g−1. This work offers an efficient and facile route, without hydrothermal treatment or adscititious alkali sources, to fabricating LDHs for boosting energy storage capabilities.

One-Dimensional Nanoscale Si/Co Based on Layered Double Hydroxides towards Electrochemical Supercapacitor Electrodes.

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing nanofibers of Si/Co LDHs through the intercalation of cyanate anions as pillars for building nanolayered structures. Additionally, nanoparticles were observed by controlling the preparation conditions and the silicon percentage. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal analyses have been used to characterize the nanolayered structures of Si/Co LDHs. The electrochemical characterization was performed by cyclic voltammetry and galvanic charge–discharge technique in 2M KOH electrolyte solution using three-electrode cell system. The calculated specific capacitance results indicated that the change of morphology from nanoparticles or plates to nanofibers had a positive effect for improving the performance of specific capacitance of Si/Co LDHs. The specific capacitance enhanced to be 621.5 F g−1 in the case of the nanofiber of Si/Co LDHs. Similarly, the excellent cyclic stability (84.5%) was observed for the nanofiber. These results were explained through the attribute of the nanofibrous morphology and synergistic effects between the electric double layer capacitive character of the silicon and the pseudo capacitance nature of the cobalt. The high capacitance of ternary Si/Co/cyanate LDHs nanocomposites was suggested to be used as active electrode materials for high-performance supercapacitors applications.