Electrode For Asymmetric Supercapacitors Research Articles

Facile synthesis of NiMoO4@MnO2 nanoflower and waste biomass-derived N, P, and S self-doped carbon for advanced asymmetric supercapacitor electrode materials

Green energy storage technologies have been demonstrated by the use of sustainable biomass-derived carbon as an electrode. Herein, for a high performance all-solid-state asymmetric supercapacitor, we used biowaste material to derive multi-heteroatom doped carbon as a non-faradaic electrode along with NiMoO4@MnO2 Nano-flower-like hybrid structure on nickel foam as a Faradaic electrode. Due to the combined effect of the large specific surface area, hierarchical porous structure of biomass-derived activated carbon (FDAC3) and the highly specific capacitance of the NiMoO4@MnO2 hybrid, designed all-solid-state asymmetric supercapacitor achieved a remarkable specific capacitance of 109.1 F g−1 at 1.4 A g−1 and maximum specific energy of 54.7 Wh/kg within a voltage window of 1.8 V. Moreover, for the practical application of designed cell devices, two different devices were connected in a series to light up different colors light emitting diodes (LEDs). These findings provide new insights to realize the full utilization of biomass waste and a novel low-cost pathway for producing high-performance materials for energy storage applications.

Rational design and synthesis of a 3D hierarchical NiCo-LDH/C/GF composite foam as advanced electrodes for asymmetric supercapacitors

Rational design and synthesis of a 3D hierarchical NiCo-LDH/C/GF composite foam as advanced electrodes for asymmetric supercapacitors

Co3O4 nanowire modified with carbon nanotubes to be used as improved asymmetric supercapacitor electrode

Co3O4 itself suffers from drawbacks such as poor conductivity and a low active site density, significantly limiting its application in capacitors. To address this issue, this study employs a one-step hydrothermal method to incorporate carbon nanotubes (CNTs) into Co3O4, resulting in the fabrication of Co3O4/CNTs composite nanomaterials. In comparison to the pristine Co3O4 material, this composite exhibits a 69.7 % improvement in specific capacitance. When Co3O4/CNTs and activated carbon (AC) are assembled into asymmetric capacitors, an impressive energy density of 58.46 Wh Kg−1 (461.52 W Kg−1) is achievable at room temperature, with a capacitance retention rate of 83.2 % observed after 65,000 charge-discharge cycles. The addition of CNTs made the Co3O4 nanowire clusters and their binding with nickel foam more tightly, increasing the conductivity of the material and exposing more active sites while improving stability. This study offers valuable insights for further advancements and practical applications of electrode materials in supercapacitors.

ZIF-67 derived high stability CoNi2S4/carbon/MXene composites as an enhanced electrode for asymmetric supercapacitor

Supercapacitors have received widespread attention from scientific researchers due to the advantages of high power density, fast charging/discharging rate and long cycle life. Among them, the development of high performance and high safety electrode materials are important research topics in the field of supercapacitors. Herein, zeolitic imidazolate framework (ZIF) derivatives is a good candidate material for supercapacitors electrode because of its controllable pore rate, constant cavity and larger specific area. However, the reunion phenomenon and the damaged structure during the reaction seriously affected its electrochemical properties, especially its stability. To solve this problem, the few-layer MXene was added into ZIF-67 to inhibit the reunion of single materials and the carbonization process was operated to improve its conductivity and structure stability. In addition, the CoNi2S4/carbon/MXene (CNS/C/MXene) obtained by the solvent thermal method successfully inherited the hollow cages structure and rough surface from the precursor, expressing a better electrochemical performance. In three-electrode system, the CNS/C/MXene electrode can exhibit the specific capacitance of 1221.6 F g−1 (169.7 mAh g−1) at 1 A g−1 and still maintain a high capacitance of 966.4 F g−1 (134.2 mAh g−1) at 20 A g−1 (79.1 % of the former). After assembling it with activated carbon into asymmetric supercapacitor, the device can provide a high energy density of 19.82 Wh kg−1 at a power density of 469.31 W kg−1 and maintain about 71.17 % of the initial capacitance after 30,000 cycles under a current density of 20 A g−1, representing excellent cycle stability and rate capability.

Vertically aligned graphene-MXene nanosheets based electrodes for high electrochemical performance asymmetric supercapacitor

Vertically aligned porous morphologies have attracted much attention due to their long-range ordered channel structures. Here, a novel 3D vertically aligned graphene-MXene nanosheets based electrochemical supercapacitor is designed. Graphene oxide and Ti3C2TX MXene are used to prepare a vertically aligned porous bridge substrate (the pore size of 7 μm) by an ice template directional solidification method. Polyaniline nanowire arrays (PANI NWAs) are in-situ grown on the substrate by a polymerization process (positive electrode) and the substrate with more MXene is used as the negative electrode. After assembling into an asymmetric supercapacitor (ASC), the vertically aligned porous morphology is conducive to accelerating the directional transport of ions, which obviously improves the electrochemical properties of the ASC. The calculated specific capacitance of the ASC is 108F/g (at 1 A/g). The energy density of the ASC can reach 38 Wh/kg (at the power density of 810 W/kg) and the cycle stability is 82 % after 10, 000 cycles at 10 A/g.

Construction of MOFs derived porous carbon based core–shell hetero-structure electrode for superior asymmetric supercapacitor

The design of electrode materials with high performance is very important to improve the energy density of supercapacitors (SCs). The combination of electrical double layer capacitor and pseudo-capacitive materials can significantly improve the electrochemical performance of material, but reasonable structural design can inhibit the slow Faraday dynamic mismatch caused by different storage mechanisms. In this study, NiCoB nanosheets were grown on the surface of cobalt metal-organic frameworks (Co-MOF) derived porous carbon (Co-C) by chemical precipitation method to form a core–shell hetero-structure Co-C@NiCoB electrode. The Co-C@NiCoB electrode has the specific capacitance of 2990 F g−1 at 1 A g−1, which is significantly higher than that of Co-C (416 F g−1) and NiCoB (1052 F g−1). In order to further increase the energy density of the device, the carbon nano-sheets with cactus shape as cathode were obtained by calcination of Co-MOF (CNS). The asymmetric SCs with CNS as cathode and Co-C@NiCoB as anode have a high energy density of 66.03 Wh kg−1 at the power density of 763.35 W kg−1 and exceptional cycling life with capacitance retention of 92.1 % over 10,000 cycles.

Synergistic CuCoS-PANI materials for binder-free electrodes in asymmetric supercapacitors and oxygen evolution.

In advanced electronics, supercapacitors (SCs) have received a lot of attention. Nevertheless, it has been shown that different electrode designs that are based on metal sulfides are prone to oxidation, instability, and poor conductance, which severely limits their practical application. We present a very stable, free-standing copper-cobalt sulfide doped with polyaniline as an electrode coated on nickel foam (CuCoS/PANI). The lightweight nickel foam encourages current collection as well as serving as a flexible support. The CuCoS-PANI electrode had a substantially greater 1659 C g-1 capacity at 1.0 A g-1. The asymmetric supercapacitor (ASC) can provide an impressive 54 W h kg-1 energy density while maintaining 1150 W kg-1 power. Additionally, when employed as an electrocatalyst in the oxygen evolution reaction, CuCoS/PANI exhibited a 200 mV overpotential and 55 mV dec-1 Tafel slope, demonstrating its effectiveness in facilitating the reaction.

Valence state regulation of iron oxide composited with graphene towards negative electrodes in asymmetric supercapacitors

A strategy based on a laser-induced method for the in situ synthesis of LIG/Fe3O4 composites was developed. The Fe3+/Fe2+ ratio was modulated to exhibit optimal electrochemical performance.

Ni0.5Co0.5S nano-chains: a high-performing intercalating pseudocapacitive electrode in asymmetric supercapacitor (ASC) mode for the development of large-scale energy storage devices.

Grid-scale energy storage solutions are necessary for using renewable energy sources efficiently. A supercapattery (supercapacitor + battery) has recently been introduced as a new variety of hybrid devices that engage both capacitive and faradaic charge storage processes. Nano-chain architectures of Ni0.5Co0.5S electrode materials consisting of interconnected nano-spheres are rationally constructed by tailoring the surface structure. Nano-chains of the bimetallic sulfide Ni0.5Co0.5S are presented to have a superior charge storage capacity. The Ni0.5Co0.5S nano-chain electrode presents a capacitance of 2001.6 F g-1 at 1 mV s-1, with a specific capacity of 267 mA h g-1 (1920 F g-1) at 1 A g-1 in 4 M KOH aqueous electrolyte through the galvanostatic charge-discharge (GCD) method. The reason behind the high charge storage capacity of the materials is the predominant redox-mediated diffusion-controlled pseudocapacitive mechanism coupled with surface capacitance (electrosorption), as the surface (outer) and intercalative (inner) charges stored by the Ni0.5Co0.5S electrodes are close to 46.0% and 54.0%, respectively. Additionally, a Ni0.5Co0.5S//AC two electrode full cell operating in asymmetric supercapacitor cell (ASCs) mode in 4 M KOH electrolyte exhibits an impressive energy density equivalent to 257 W h kg-1 and a power density of 0.73 kW kg-1 at a current rate of 1 A g-1.

A 3D hydrangea-like NiMoO4/rGO/PANI hybrid composite for high performance asymmetric supercapacitor

Development of electrode materials exhibiting exceptional stability and possessing a high specific capacitance is the important task within the realm of supercapacitor research. In this study, a novel micro-architecture of NiMoO4 (NMO) resembling a hydrangea in three dimensions (3D) has been developed. The surface of NMO was modified by anchoring PANI nanoparticles and reduced graphene oxide (rGO) resulting in the formation of a composite material designated as NiMoO4/rGO/PANI (NMORP). The NMORP composite demonstrates a notable increase in specific-capacity, reaching 1150 C g−1 when tested at 1 A g−1. The observed capacity retention percentage of 97.5 % after undergoing 5000 cycles on a notable current density (10 A g−1) provides substantial proof of exceptional cycling performance within the cycling domain. The remarkable outcomes observed can be attributed to the synergistic impact of the structural and componential characteristics of the NMORP composite. The higher cycling stability of the NMORP composite electrode may be ascribed to the 2D–2D coupling phenomenon occurring at the interface of reduced graphene oxide (rGO) and NMO nanosheets, together with the stable 3-D design reminiscent of hydrangea flowers. Furthermore, the NMORP composite, characterized by a pore structure ranging from 10 to 20 nm and higher conductivity, demonstrates enhanced capabilities regarding the transfer of charge and diffusion of ions. In addition, the NMORP//AC supercapacitor shows a remarkable energy density of 82.43 Wh kg−1 at 850 W kg−1 power density. Furthermore, it shows exceptional cycling performance, retaining 94.5 % of its capacity with 10 A g−1 current density upon the completion of 10,000 cycles. The fabrication of a composite material, referred to as NMORP, presents a viable approach to address the challenges associated with the inadequate electrochemical durability and sluggish electron/ion transfer exhibited by NMO composite when utilized as an electrode in asymmetric supercapacitors (device).

Diffusion-dominated redox performance of hydrated copper molybdate for high-performance energy storage

High-performance hydrated phase copper molybdate with improved electrochemical performance is reported for hybrid supercapacitors.

A new binder-free ZnS-CuO microsphere: A battery-type electrode material for asymmetric supercapacitor

The supercapacitor has emerged as a viable solution to address the energy demands of industries and mitigate the environmental concerns associated with fossil fuel utilization. Hence, in this study, binder-free ZnS-CuO microspheres are reported for the first time and directly utilized as a battery-type electrode for asymmetric supercapacitor (ASC) applications. The current study demonstrates an exceptional electrochemical performance by optimizing the composition, structure, and morphology. The increased surface area and abundance of active sites contribute to the enhanced ion transfer efficiency between the electrolyte and the electrode, promoting rapid ion exchange. The electrochemical properties reveal a maximum capacitance of 561 F/g with excellent charge storage capacity, and good rate capability. The CuO-ZnS||AC ASC was built that operates in a broad voltage window of 1.6 V, and a capacitance of 175 F/g in an aqueous solution. It delivers the highest specific energy of 62 Wh/kg with an excellent power delivery of 8640 W/kg and remarkable stability of 93.2 % after 5000 cycles. Nevertheless, there is a prevailing optimism regarding the potential for optimizing synthesis procedures, which may ultimately result in the practical implementation of these innovative materials for efficient energy storage in the near future.

Facile synthesis of layered reduced graphene oxide/polyaniline (rGO/PANI) composite electrode for flexible asymmetric solid-state supercapacitor

For supercapacitors, composite electrodes with a combination of reduced graphene oxide and polyaniline (rGO/PANI) have gained a lot of attention due to their synergistic effects. In this study, rGO-PANI composite thin films were deposited on a stainless steel substrate with various mass loadings by successive ionic layer adsorption and reaction (SILAR) method. The specific surface area rises from 13 m2 g−1 to 30 m2 g−1 with the introduction of rGO. Due to the composition modification and specific surface area enhancement, the specific capacitance (capacity) of 1348 F g−1 (1255C g−1) was obtained at 0.89 mg cm−2 mass deposition. Additionally, rGO/PANI/PVA-H2SO4/AC flexible asymmetric solid-state supercapacitor (ASSS) showed specific energy of 20 Wh kg−1 at specific power of 1198 W kg−1. The device maintained almost 96 % of Cs at bending angle of 160° and 75 % over 5000 cycles. This work illustrates a simple way to improve the capacity and stability of PANI via rGO composition for supercapacitor applications.

Cobalt-Nickel Layered Double Hydroxides on Electrospun MXene for Superior Asymmetric Supercapacitor Electrodes.

Flexible electrodes for energy storage and conversion require a micro-nanomorphology and stable structure. Herein, MXene fibers (MX-CNF) are fabricated by electrospinning, and Co-MOF nanoarrays are prepared on the fibers to form Co-MOF@MX-CNF. Hydrolysis and etching of Co-MOF@MX-CNF in the Ni2+ solution produce cobalt-nickel layered double hydroxide (CoNi-LDH). The CoNi-LDH nanoarrays on the MX-CNF substrate have a large specific surface area and abundant electrochemical active sites, thus ensuring effective exposure of the CoNi-LDH active materials to the electrolyte and efficient pseudocapacitive energy storage and fast reversible redox kinetics for enhanced charging-discharging characteristics. The CoNi-LDH@MX-CNF electrode exhibits a discharge capacity of 996 F g-1 at a current density of 1 A g-1 as well as 78.62% capacitance retention after 3,000 cycles at 10 A g-1. The asymmetric supercapacitor (ASC) comprising the CoNi-LDH@MX-CNF positive electrode and negative activated carbon electrode shows an energy density of 48.4 Wh kg-1 at a power density of 499 W kg-1 and a capacity retention of 78.9% after 3,000 cycles at a current density of 10 A g-1. Density-functional theory calculations reveal the charge density difference and partial density of states of CoNi-LDH@MX-CNF confirming the large potential of the CoNi-LDH@MX-CNF electrode in energy storage applications.

Attaining high energy density using metal-organic framework-derived NiO/Co3O4/NiCo2O4 as an electrode in asymmetric hybrid supercapacitor

This study investigates the potential of hybrid NiO/NiCo2O4/Co3O4 composite as electrode for high-performance supercapacitors. Hydrothermally synthesized Ni(BDC) and Co(BDC) as sacrificial templates with different mass ratios are used to obtain NiO/NiCo2O4/Co3O4 nanocomposite. Notably, the electrochemical studies revealed that NiO/NiCo2O4/Co3O4 derived from a 4:1 mass ratio of Ni-MOF and Co-MOF displayed the highest specific capacity value of 1108.9C g−1 at 2 A g−1 with enhanced rate capability and excellent electrochemical stability, with 95.3 % retention up to 5000 cycles at 10 A g−1. The enhancement of specific capacity is attributed to the multiple metal oxidation states (Ni2+, Ni3+, Co2+, Co3+), surface oxygen defects, and the reduced solvation effect due to mesoporous structure and higher specific surface area. The assembled hybrid asymmetric supercapacitor (NiO/NiCo2O4/Co3O4 //Carbon Black) demonstrated a remarkable specific capacity of 416.95C g−1 at 0.5 Ag−1 with 89.1 % retention up to 5000 cycles at 10 A g−1 and an exceedingly high energy density of 89.81 W h kg−1 at a power density of 387.49 W kg−1. Even at a high-power density value of 7740 W kg−1, the device maintained an impressive energy density of 72.43 W h kg−1.

Self-assembled microflower-like NiCo2X4 (X = O, S, Se) as electrodes for asymmetric supercapacitors

The substitution of chalcogen elements has a notable influence on the microstructure and electrochemical properties of transition metal oxides. However, the underlying mechanism necessitates clarification. In this investigation, self-assembled microflower-like NiCo2X4 (X = O, S, Se) structures were successfully synthesized, and their microstructures and electrochemical performance were systematically examined using both theoretical and experimental approaches. Theoretical analysis demonstrated that the replacement of chalcogen elements significantly enhances the energy band structure of the material, thus effectively improving its electrochemical performance. Experimental results revealed that, in comparison to NiCo2O4 and NiCo2S4, NiCo2Se4 displayed remarkable electrochemical performance, with a specific capacitance of 1899 F g–1 at a current density of 1 A g–1 and a promising rate capability (with a capacitance retention increase of up to 71.9% when the current density was elevated from 1 A g–1 to 10 A g–1). Additionally, the asymmetric device (NiCo2Se4//AC), composed of NiCo2Se4 as the positive electrode and activated carbon (AC) as the negative electrode, exhibited an energy density of 42.44 Wh kg–1 at a power density of 1600 W kg–1. As a result, this study offers novel insights into the fabrication of transition metal compounds for energy storage applications.

Flexible and sewable electrode based on Ni-Co@PANI-salphen composite-coated on textiles for wearable supercapacitor

Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that exhibit exceptional capacitive performance. Herein, we have prepared Ni-Co nanoparticles at the surface of polyaniline-salphen (Ni-Co@PS). Then, followed by casting Ni-Co@PS on a conductive carbon cloth (CC) as a substrate through a facile in-situ polymerization strategy. The morphologies of Ni-Co@PS composite were characterized by different methods such as FE-SEM, XPS, XRD, BET, and electrochemical methods. This nanocomposite showed high tolerability and a large surface area with excellent behavior as a new nanomaterial for supercapacitor application. Thus, the optimum composite designed with a metal ratio (nickel–cobalt 3:1 w/w) satisfactorily possesses a specific capacitance of up to 549.994 C g−1 (1447.2 F g−1) under 0.5 A g−1 and long-term cyclic stability featuring capacity retention of 95.9% after 5000 cycles at a current density of 9.0 A g−1. The Ni-Co@PS-CC, is a material with great potential as an electrode in asymmetric wearable supercapacitor (AWSC) apparatus, demonstrating a remarkable specific capacity of 70.01, and accompanied by an energy density of 23.46 Wh k g−1 at a power density of 800 W k g−1.

Uniform Co9S8 nanosheets on carbon nanotube arrays grown on Ni mesh as free-standing electrodes for asymmetric supercapacitors

A free-standing 3D core/shell composite material CNTs@Co9S8 on nickel mesh has been prepared by a simple two-step method. Carbon nanotubes (CNTs) grown vertically on the surface of nickel mesh by chemical vapor deposition (CVD) method act as conductive skeleton. Then Co9S8 nanosheets uniformly aligned on the surface of the CNTs by solvothermal method are interconnected to form a honeycomb structure. Owing to the close contact of the CNTs@Co9S8 hybrid with the nickel mesh and the hierarchical 3D porous structure, the prepared Ni@CNTs@Co9S8 electrodes exhibit low resistance and excellent charge storage capability with a specific capacitance of 1305.4 F g−1 at 1 A g−1. The composite delivers an excellent rate capability with 84.3 % capacitance retention at 10 A g−1. An asymmetric supercapacitor composed of Ni@CNTs@Co9S8 and nitrogen-doped carbon nanotubes (NCNTs) shows an energy density of 23.8 Wh kg−1 and a high power density of 8007.4 W kg−1. The specific capacitance of the ASC device remained 87.31 % after 10,000 charge-discharge cycles and two tandem ASCs can power two red LED diodes for at least 7 min, suggesting the potential application of the obtained free-standing electrode for supercapacitors.

N-doped bimetallic sulfides hollow spheres derived from MOF as battery-type electrode for asymmetric supercapacitors

Despite the significant progress in bimetallic MOFs electrodes, strategies to seamlessly interconnect of hollow spherical structure MOFs and electrically conductive substrate materials without adhesives are still deficient. In this study, we designed an original method for in situ synthesis of hollow spherical bimetallic MOF-derived sulfides (HN2CMS) on nickel foam by using self-grown ZIF-67 on nickel foam as precursor and template followed by two simple hydrothermal reactions. The prepared electrodes exhibit a high specific capacitance of 938.1C g−1 at the current density of 1 A g−1, low electrochemical resistance and excellent cycling stability (85.0 % after 5000 cycles) in a 3 M KOH aqueous electrolyte. More importantly, an assembled asymmetric supercapacitor based on HN2CMS provides an ultra-high energy density of 51.2 Wh kg−1 with a power density of 800 W kg−1. And it exhibits an outstanding lifetime of 81.1 % capacity remained after 5000 cycles, demonstrating that hollow spherical bimetallic MOF-derived sulfides are a prospective candidate for SC electrode materials. This synthesis method breaks a new path to developing binder-free electrodes with hollow structures based on bimetallic MOFs, thus improving the electrochemical performance of asymmetric SC.

Azopyridine as a Linker Molecule in Polyaniline-Grafted Graphene Oxide Nanocomposite Electrodes for Asymmetric Supercapacitors

Azopyridine as a Linker Molecule in Polyaniline-Grafted Graphene Oxide Nanocomposite Electrodes for Asymmetric Supercapacitors