Electrode Material For High-performance Supercapacitors Research Articles

Ni-In-oxalate nanostructure as electrode materials for high-performance supercapacitors

Energy storage technologies play a crucial role in addressing the intermittent characteristics of renewable energy sources, improving the stability of electrical grids, and decreasing the release of greenhouse gas emissions. In this study, we presented nickel indium oxalate (Ni1-xInxC2O4) as a promising material with potential applications in the field of electrochemical energy storage. The as-prepared Ni-In- oxalate sample was subjected to different physical characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Regarding the electrochemical energy storage capability, the Ni1-xInxC2O4 electrode material exhibited a specific capacitance of 835 F g-1 (417.5 C g-1) at 1 A g-1. The incorporation of nickel into the indium oxalate nanoplates enhances their electrochemical performance. The presence of nickel in the nanoplates generated from substrate, improving the overall conductivity of the material and enhances its electrochemical reactions, thus leading to improved energy storage capabilities.

Electrochemical analysis of sol-gel and hydrothermal synthesized mesoporous strontium titanate spherical nanoparticles as electrode material for high-performance flexible supercapacitors

Perovskite oxides with large specific surface areas present a promising avenue for enhancing supercapacitor efficiency. This study investigates the remarkable charge storage capabilities of strontium titanate (SrTiO3, STO) synthesized via sol-gel and hydrothermal techniques for electrochemical energy storage applications. The cubic crystal structure of STO, confirmed from X-ray Diffraction analysis, synthesized at lower temperatures through both methods, provides three-dimensional diffusion channels for oxygen anion movement, which is crucial for improving charge storage capacity. X-ray photoelectron spectroscopy confirmed the elements’ oxidation states and their spin-orbit splitting. The spherical nanoparticle morphology was observed in the FESEM images, BET characterization revealed a high specific surface area contributing to more charge storage and mesoporous nature facilitates excellent mass transfer rates of electrolytic ions. Electrochemical measurements and calculations confirmed that sol-gel and hydrothermally synthesized STO electrodes exhibit maximum specific capacitances of 130 F g−1 and 156 F g−1 at 10 mV s−1, respectively. A fabricated flexible supercapacitor device in an aqueous medium maintains a constant voltage of 1.2 V, capable of powering a digital watch. Hence, this study demonstrates the potential of STO electrode-based supercapacitors for a wide range of electrochemical energy storage applications.

High-performance NF-loaded F-NiFe-LDH/rGO nanoflower/nanosheet composite electrode material achieving enhanced specific capacitance and energy density for supercapacitor

High-performance nanostructured F-NiFe-LDH/rGO composite electrode materials with F-NiFe-LDH nanoflowers and rGO nanosheets are synthesized in a controlled hydrothermal method by leveraging the strong synergistic effects between the components, enabling the construction of F-NiFe-LDH/rGO//AC asymmetric supercapacitors. The incorporation of rGO significantly enhances electron transport, resulting in an exceptional specific capacitance of 2860 F g−1 at a current density of 1 A g−1, with a remarkable capacity retention of 102 % after 1000 cycles. This represents a notable improvement in electrochemical energy storage, with surface-controlled capacitance contributing more in alkaline electrolytes for F-NiFe-LDH/rGO composite compared to F-NiFe-LDH alone. The asymmetric supercapacitor device exhibits a specific capacitance of 354 F g−1 at 1 A g−1, maintaining 92.31 % of its initial capacitance after 1000 charge/discharge cycles at 5 A g−1, and achieves an impressive energy density of 110 Wh kg−1 at 1 A g−1. The innovation of this work lies in the controllable preparation of nanostructured F-NiFe-LDH-rGO supercapacitor electrode material with enhanced specific capacitance and energy density by the synergistic effect between F-NiFe-LDH and rGO. This work offers a solid foundation for creating high-performance supercapacitor electrode materials and devices for energy storage applications.

Synthesis of rice husk derived porous carbon as low-cost and high-performance electrode material for supercapacitors

Porous carbon electrode materials derived from agricultural by-products of food processing have attracted widespread interest. Rice husk (RH) is a promising raw material owing to its abundance and low price. In this study, a supercapacitor electrode was prepared by using recycled RH and secondarily activated with ZnCl2 to enhance its electrochemical energy storage performance. RH carbonized at the optimum temperature (i.e., 800 °C) was activated to synthesize RH-800-X (X = 1, 2, 3, 4, or 5, representing the mass ratio of ZnCl2 to RH-800). Sample RH-800-3 exhibited the highest specific surface area (1348.29 m2 g−1) and mesoporous pore volume (0.8375 cm3 g−1) among the samples. In a three-electrode system, the prepared electrodes delivered a high specific capacitance (242 F g−1 at 0.3 A g−1 in 6 M KOH solution). Furthermore, the capacitance retention of RH-800-3 remained at 99.9 % after 17,000 charge/discharge cycles. The results demonstrate the excellent capacitive behavior and superior electrochemical performance of RH-800-3. In addition, symmetrical capacitors prepared using RH-800-3 have an energy density of up to 101 Wh kg−1 at a power density of 900 W kg−1. Therefore, this study presents a simple and effective method for preparing a high-performance electrode material from biomass-derived porous carbon (i.e., recycled RH) and offers a new perspective for the efficient utilization of waste biomass resources.

Marigold flower-like structured battery-type Cu2O/Co(OH)2 composite electrode material for high-performance supercapacitors

Addressing the limitations of individual Cu2O and Co(OH)2 components, this study aims to develop a high-performance supercapacitor electrode by synergistically combining these materials. A composite electrode material of Cu2O/Co(OH)2 was effectively synthesized on nickel foam via a facile hydrothermal method for supercapacitor applications. The as-fabricated Cu2O/Co(OH)2 composite electrode exhibits a hierarchical marigold flower-like morphology that comprises of many interspersed nanoflakes. This unique morphology offers several advantages, including increased surface area, abundant electroactive sites, and enhanced electrolyte accessibility, all of which contribute to superior electrochemical performance. The Cu2O/Co(OH)2 electrode demonstrates exceptional battery-type supercapacitor behavior, characterized by prominent redox peaks in cyclic voltammetry curves and a well-defined potential plateau during galvanostatic charge-discharge measurements. The electrode delivers an outstanding specific capacitance of 90.21 mA h g⁻1 at a current density of 1.25 A g⁻1 and retains a remarkable 81.91 % capacitance at a high current density of 12.5 A g⁻1. Furthermore, the electrode exhibits impressive cycling stability, maintaining approximately 107.84 % of its initial specific capacity value after 200 cycles at 7.5 A g⁻1. Electrochemical impedance spectroscopy measurements reveal low solution resistance and charge-transfer resistance, signifying efficient charge-transfer kinetics within the electrode. These findings highlight the potential of Cu2O/Co(OH)2 composite electrodes as promising candidates for high-performance supercapacitor applications.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

Synthesis of NiFeCo ternary layered hydroxides and their performances of electrochemical energy storage for solar cells

Ternary layered hydroxide are high-performance electrode materials for supercapacitors. In this study, nickel–iron-cobalt ternary layered hydroxides (NiFeCo-LDHs) with different nickel–iron molar ratios were grown on nickel foam using a one-step hydrothermal method. The effect of nickel–iron molar ratio on the electrochemical performance and morphology of NiFeCo-LDHs was investigated, and the electrode material at a nickel–iron molar ratio of 3:7 had better electrochemical performance up to 7.01F/cm2 (at 1 mA/cm2). The specific capacitance of the assembled hybrid supercapacitor reached 1575.00 mF/cm2 at 3 mA/cm2. In addition, the fabricated all-solid-state hybrid capacitor（742.86 mF/cm2 at 4 mA/cm2) was capable of lighting an LED after charged by a solar cell. The results indicated that the electrochemical performance of NiFeCo-LDHs was affected by the nickel–iron mole ratio and demonstrated the potential application of NiFeCo-LDHs in electrochemical energy storage.

Corncob-Derived Activated Carbon as Electrode Material for High-Performance Supercapacitor.

In this study, corncob was explored as a low-cost and abundant precursor for the preparation of activated carbon via carbonization and the KOH activation method. The alkaline/biochar ratios varied from 3:1 to 5:1, and the activation temperatures ranged from 700 to 900 °C. The characterized results reveal that the alkaline/biochar ratios and activation temperatures had a remarkable influence on the morphology and microstructure of as-prepared activated carbon (CACT-R). The CACT-R presented a porous structure with a large number of micropores and a small number of mesopores. The reasonable distribution of micropores and mesopores endows the ideal structure for ion transfer and charge storage. The optimal sample CAC700-4 exhibited the best capacitive performance with a specific capacitance of 260 F/g at 1 A/g. Moreover, the assembled CAC700-4//CAC700-4 symmetric supercapacitor showed a high energy density of 14.3 Wh/kg at a power density of 250 W/kg in 6 M KOH electrolyte. It also has a capacitance retention of 95.5% after 10,000 cycles, indicating its excellent cycle stability. These results indicate that corncob-derived activated carbon provides the possible application of biomass waste in high-performance supercapacitors.

Activated biomass-derived 3-dimensional porous graphene-like carbon for high-performance energy storage electrode materials

This article reports studies on the fabrication of active material for supercapacitor electrodes, from 3D porous graphene-like carbon (GLC), synthesized by carbonization from coffee waste (CW) and tea waste (TW) at 550 °C, followed by thermochemical activation in KOH at 850 °C in a quartz tubular furnace. The microstructure of coffee and tea waste shows the form of micro- and mesopores during carbonization and further chemical activation forms hierarchically highly porous 3D graphene-like carbon. GLC-CW exhibited a higher specific surface area (SSA) of 3486 m2/g according to the Brunauer-Emmett-Teller (BET) method, compared to GLC-TW, which had an SSA of 2407 m2/g. These results highlight the effectiveness of graphene-like carbon derived from coffee and tea waste, demonstrating its potential as a promising material for high-capacity supercapacitors. The electrochemical characteristics of the assembled supercapacitors using GLC-CW and GLC-TW revealed significantly higher specific capacitance values of 214 F/g and 182 F/g respectively, along with cycling stability of 98 % and 95 % during 5000 cycles of charge and discharge at 2 A/g current density. This approach can produce high-performance electrode materials for supercapacitors at a reasonable cost and with easy scalability.

Luffa vines-derived N, O doped porous carbon with high surface area for supercapacitors

Considerable attention has been devoted to creating porous carbons with exceptional surface area and porosity from biomass waste for energy storage devices. Herein, we employed a straightforward high-temperature carbonization and KOH activation method to synthesize nitrogen (N) and oxygen (O) co-doped porous activated carbons derived from luffa vines (LVACs). The impact of varying KOH concentrations on the morphology, structure, and electrochemical properties of LVACs was thoroughly investigated. The optimal mass ratio of KOH to LVACs at 1:6 achieved the maximum specific surface area of 3369 m2 g−1. At a current density of 1 A g−1, the LASC-6 electrode exhibits an impressive specific capacitance of 348.5 F g−1. It also demonstrates exceptional rate performance, retaining 70.6 % of its capacitance at a current density of 20 A g−1. The electrode possesses robust cycling stability, retaining 90 % of the initial capacitance after 5000 cycles. We assessed the practicality of LVAC-6 by constructing symmetric supercapacitors (SSCs) using KOH and [BMIM]BF4 electrolytes. The KOH and [BMIM]BF4 SSCs achieved specific capacitances of 86.75 and 50.31 F g−1, respectively, at a current density of 0.25 A g−1. Moreover, the [BMIM]BF4 SSC exhibited an impressive energy density of 51.05 Wh kg−1 at a power density of 346.15 W kg−1. Therefore, we propose a simple and cost-effective strategy to produce porous carbon materials with excellent electrochemical performance from discarded biomass waste, facilitating the preparation of environmentally friendly electrode materials for high-performance supercapacitors.

NiCo layered double hydroxides/carbon dots composites with S-doing for high-performance asymmetric supercapacitors

The pursuit of high-performance electrode materials for supercapacitors has led to the exploration of transition metal layered double hydroxides (LDH), which boast an impressive theoretical specific capacitance. However, their intrinsic limitations, such as poor electronic conductivity and slow diffusion kinetics, have posed significant challenges for their practical implementation. In this work, a NiCo LDH/carbon dots (CDs) composite with S-doping has been meticulously designed to overcome the aforementioned limitations through a synergistic combination of heteroatom doping and carbon incorporation. Utilizing a one-pot hydrothermal method, the composite electrode for the application of asymmetric supercapacitors have been in-situ growth on Ni foam substrate, which not only serves as a robust support but also contributes to the formation of NiCo LDH by providing a uniform Ni source, thereby ensuring strong adhesion and structural integrity. The morphology and microstructures of composites could be finely modulated by adjusting CDs amount. With moderate CDs contents, the optimum electrode S-LDH/CDs-2 exhibits distinctive 3D needle-like spherical morphology, coupled with the ample space for ion diffusion. Consequently, the electrode demonstrates outstanding electrochemical performance, featuring a high areal capacitance of 5157 mF cm−2 at a current density of 2 mA cm−2. Additionally, it exhibits noteworthy rate performance and maintains excellent cycling stability. Integrating the innovative electrode into asymmetric supercapacitors configuration, superior energy density (0.24–0.45 mWh cm−2) and power density (4–20 mW cm−2) as well as good stability have been achieved for the S-LDH/CDs-2//AC device. These results indicate that S-doped NiCo LDH/CDs composite electrode has the desirable potential to be a candidate for energy storage devices.

Core-shell structured MgCo2O4@Ni(OH)2 nanorods as electrode materials for high-performance asymmetric supercapacitors

In the field of energy storage, supercapacitors have received extensive attention in recent years. However, achieving the expected electrochemical performance and energy density of supercapacitors is still a huge challenge. The design and synthesis of binder-free composite electrode with core–shell structure is an effective strategy to improve the electrochemical performance of supercapacitors. In this paper, a heterogeneous core–shell structured and binder-free electrode material MgCo2O4@Ni(OH)2 (MCO@NH) grown on nickel foam (NF) is prepared by a simple hydrothermal and oil bath method. The unique core–shell structure makes the MCO@NH have a large specific surface area, which provides abundant active sites for ion transport and storage, thereby improving the electrochemical performance. The MCO@NH/NF nanocomposite demonstrates a high specific capacitance (Cs) of 1583 F g−1 at 1 A/g. A solid-state asymmetric supercapacitor (ASC) assembled with MCO@NH/NF and active carbon (AC) exhibits excellent energy density (45 Wh kg−1 at 457.5 W kg−1) and outstanding capacitance (89.51 %) and coulombic efficiency (97.8 %) after 12,000 cycles, evidencing its good operation stability and potential practical applications. Therefore, the prepared core–shell MCO@NH/NF electrode can be a promising candidate for energy storage devices.

Mangenese Copper Selenide Nanosheet Arrays Derived from Metal-Organic Frameworks for Efficient Solid-State Asymmetric Supercapacitors

Metal chalcogenide nanostructures, particularly metal selenides, have unique properties, such as high electrical conductivity, large specific surface area, exclusive porous networks, and exceptional electrochemical properties compared to traditional nanostructures.1 2 A novel strategy is proposed to design and fabricate hierarchical Manganese copper selenide nanosheet (MnCuSe NS) arrays from metal-organic frameworks (MOFs). The hierarchical MnCuSe NS arrays can deliver enriched electroactive sites and shorten the ion/electron diffusion pathways. When evaluated as positive electrodes for supercapacitor (SC), the MnCuSe NS electrode displayed remarkable electrochemical properties with ultra-high specific capacity of ≈350.4 mA h g− 1 and an areal capacity of ≈0.94 mA h cm− 2 at a current density of 3 mA cm− 2, exceptional rate capability (≈79.5% of the capacity retention at a higher current density of 50 mA cm− 2), and outstanding cyclic stability (≈95.4 % of capacity retention after 10 000 cycles). Most importantly, the assembled MnCuSe NS//FeMnO/NG solid-state asymmetric SC exhibited a wide operating potential window of 1.6 V with an ultra-high volumetric capacity of ≈2.4 mA h cm− 3 at a current density of 3 mA cm− 2, an excellent energy density of ≈71.6 Wh Kg− 1 at a power density of ≈794 W Kg− 1, and ultra-long cycle life (≈93.4 % of capacity retention after 10 000 cycles). This proposed method provides a general protocol to design and fabricate metal selenide nanosheet arrays with superior electrochemical energy storage properties and exceptional cyclic stability, holding significant potential for future energy storage devices in commercial aspects. Keywords: Hierarchical, Metal-organic frameworks, Metal chalcogenide, Energy density, Asymmetric supercapacitorsReference:(1) Han, J. H.; Kwak, M.; Kim, Y.; Cheon, J. Recent Advances in the Solution-Based Preparation of Two-Dimensional Layered Transition Metal Chalcogenide Nanostructures. Chem. Rev. 2018, 118 (13), 6151–6188. https://doi.org/10.1021/acs.chemrev.8b00264.(2) Karuppasamy, K.; Vikraman, D.; Hussain, S.; Kumar Veerasubramani, G.; Santhoshkumar, P.; Lee, S.-H.; Bose, R.; Kathalingam, A.; Kim, H.-S. Unveiling a Binary Metal Selenide Composite of CuSe Polyhedrons/CoSe2 Nanorods Decorated Graphene Oxide as an Active Electrode Material for High-Performance Hybrid Supercapacitors. Chemical Engineering Journal 2022, 427, 131535. https://doi.org/10.1016/j.cej.2021.131535.

Facile synthesis of MnMoO4 nanostructures arrays as novel electrode materials for high-performance symmetric and asymmetric supercapacitor

Facile synthesis of MnMoO4 nanostructures arrays as novel electrode materials for high-performance symmetric and asymmetric supercapacitor

Biomass-tar-derived oxygen-enriched porous carbon as a high-performance carbon electrode material for double electric layer and zinc-ion hybrid supercapacitor

Carbon-based capacitor electrodes have the advantages of high capacitance value, superior recyclability, and inexpensive raw materials, which fuel the application of capacitors in large-scale energy storage. Biomass tar is a hazardous waste that can be recycled as a low-cost carbon electrode precursor for capacitors, due to its retaining biomass-based heteroatom. In this study, hierarchically porous carbon with cross-linked structure was fabricated by using a nano-Al2O3 template combined with the KOH activation technique, in which the γ-Al2O3 has a size of only 10 nm with high specific surface area, thus optimizing the pore structure of the carbon material. The resulting optimal material, BTC-0.2-2-800, contains abundant pore structure and extremely high oxygen content, delivers low resistance and excellent rate performance with high specific capacitance of 292.1 F g−1 and 221.7 F g−1 at 1 A g−1 and 20 A g−1, respectively, in double electric layer supercapacitors (EDLCs). Besides, no significant capacity degradation after 10,000 charging and discharging cycles at 10 A g−1 was found. The two-electrode device prepared using Na2SO4 electrolyte achieves a high energy density of 43.18 Wh kg−1 at the power density of 1000 W kg−1, which can light up a 2 V LED lamp. Moreover, Zinc-ion hybrid supercapacitor (ZIHSC) fabricated with BTC-0.2-2-800 carbon electrode accounts for the energy densities of 69.82 Wh kg−1 and 49.39 Wh kg−1 at the power densities of 40 W kg−1 and 400 W kg−1, respectively. This study reveals the great potential of biomass-tar-derived carbon as a high-performance electrode material, which may provide an opportunities for the resource utilization of hazardous wastes.

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.

Novel three-dimensional architectured ZnMgAl ternary layered double hydroxide@reduced graphene oxide nanocomposites as electrode material for high-performance supercapacitor

Ternary layered double hydroxides (LDH) have recently attracted immense attention owing to their stupendous features, such as fine compositional tuning, multiple valence states, and superior electrochemical activity. Moreover, their intriguing structures and distinctive physiochemical properties delineate them as an exemplary material to serve as electrodes for high-performance supercapacitors (SCs). The present work reports the in-situ synthesis of Zinc Magnesium Aluminium LDH (ZMA) integrated with reduced graphene oxide (rGO) through a single-step hydrothermal approach. The resulting novel ternary ZMA@rGO nanocomposite (ZMAG) possesses a unique architecture incorporating hierarchical 3D nanoflowers of ZMA embedded on graphene nanosheets. The porous morphology of LDH improves interfacial charge transport, which results in more faradaic reactions at the electrochemically active sites. In addition, the conductive graphene nanosheets render a high specific surface area, endowing excellent capacitive behavior. The amalgamated electrochemical properties of ZMA and rGO develop a competent electrode material (ZMAG) for SCs. The ZMAG2 nanocomposite having ZMA and rGO in 1:1, evinces a specific capacitance (Cs) of 656.7 F/g at a current density (Id) of 1 A/g. Furthermore, the asymmetric supercapacitor (ASC) features admirable cycle stability (retains 89% of initial capacitance after 15,000 charge/discharge cycles). Herein, the real-time application of ZMA@rGO//AC ASC has also been demonstrated. Therefore, hierarchical porous nanostructure proclaims new prospects for fabricating proficient electrode materials for energy storage devices.

Ni3V2O8 Marigold Structures with rGO Coating for Enhanced Supercapacitor Performance.

In this work, Ni3V2O8 (NVO) and Ni3V2O8-reduced graphene oxide (NVO-rGO) are synthesized hydrothermally, and their extensive structural, morphological, and electrochemical characterizations follow subsequently. The synthetic materials' crystalline structure was confirmed by X-ray diffraction (XRD), and its unique marigold-like morphology was observed by field emission scanning electron microscopy (FESEM). The chemical states of the elements were investigated via X-ray photoelectron spectroscopy (XPS). Electrochemical impedance spectroscopy (EIS), Galvanostatic charge-discharge (GCD), and cyclic voltammetry (CV) were used to assess the electrochemical performance. A specific capacitance of 132 F/g, an energy density of 5.04 Wh/kg, and a power density of 187 W/kg were demonstrated by Ni3V2O8-rGO. Key electrochemical characteristics were b = 0.67; a transfer coefficient of 0.52; a standard rate constant of 6.07 × 10-5 cm/S; a diffusion coefficient of 5.27 × 10-8 cm2/S; and a series resistance of 1.65 Ω. By employing Ni3V2O8-rGO and activated carbon, an asymmetric supercapacitor with a specific capacitance of 7.85 F/g, an energy density of 3.52 Wh/kg, and a power density of 225 W/kg was achieved. The series resistance increased from 4.27 Ω to 6.63 Ω during cyclic stability tests, which showed 99% columbic efficiency and 87% energy retention. The potential of Ni3V2O8-rGO as a high-performance electrode material for supercapacitors is highlighted by these findings.

Facile synthesis of samarium (Sm3+) doped cobalt-iron oxide nano ferrite as an advanced electrode material for possible supercapacitor applications

Herein, we present design and fabrication of Samarium (Sm3+) doped cobalt-iron oxide ferrites nanocomposite electrode as an efficient energy storage material for supercapacitors. We employed a simple, low cost and quick one step solution combustion method to synthesize CoFe2-xSmxO4 (x = 0.0, 0.050, 0.075 and 0.1) ferrites. The morphological and structural features of synthesized CoFe2-xSmxO4 ferrites were analysed through various analytical and spectroscopic characterization methods such as scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). These analytical techniques confirm the successful doping of Samarium (Sm3+) into cobalt-iron ferrite, and the doping does not affect the crystalline structure of pure ferrite. The electrochemical properties of the synthesized ferrites were significantly improved after Samarium (Sm3+) doping into the host cobalt-iron-oxide. The highest specific capacity about 314 F/g was achieved for CoFe2-xSmxO4 (x = 0.1) composite electrode material, in comparison to pure CoFe2-xSmxO4 (x = 0) which is about 125 F/g. However, CoFe2-xSmxO4 (x = 0.1) ferrite shows a superior capacitance retention of the order of 98 % even after 5000 cycles of operation at a scan rate of 250 mV/s. The electrode material fabricated by using CoFe2-xSmxO4 ferrite renders an energy density of 30.16 W h/kg at a power density of 400 W h/kg. The results obtained in presented studies opens new avenues for the fabrication high-performance electrode material for supercapacitor that could be well suited for light weight electronic devices, electric vehicles, and forthcoming generation supercapacitor applications.

Dense graphene composite hydrogels as advanced electrode materials for high-performance supercapacitors

In this work, alanine functionalized nanocellulose/graphene composite hydrogels (NCGHalas) were prepared via an easy hydrothermal reaction using alanine, GO, and nanocellulose as reactant. Thanks to this synthesis strategy, NCGHalas exhibited large bulk density, abundant heteroatom functional groups, reasonable porous structure and moderate specific surface area. Based on the above characteristics, the aqueous symmetric supercapacitors (ASSC) assembled by NCGHala25 presented high gravimetric and volumetric specific capacitance of 276.5 F g−1 and 320.8 F cm−3 at 0.3 A g−1, excellent rate performance (77.9 % at 10 A g−1), and long working life of 95.4 % retention after 10,000 cycles at 10 A g−1. Furthermore, the NCGHala25 based ASSC also exhibited large gravimetric and volumetric specific energy densities of 9.6 Wh kg−1 and 11.1 Wh L−1. More importantly, the flexible solid-state supercapacitors (FSSC) fabricated by NCGHala25 and PVA-KOH electrolyte delivered high specific capacitance (178.2 F g−1, 0.3 A g−1), and this value can be maintained for 74.2 % even at 10 A g−1.