Electrodes For High-performance Hybrid Supercapacitors Research Articles

RGO-Induced Flower-like Ni-MOF In Situ Self-Assembled Electrodes for High-Performance Hybrid Supercapacitors.

Currently, the primary bottlenecks that hinder the widespread application of supercapacitors are low energy density and narrow potential windows. Herein, the hybrid supercapacitor with high energy density and wide potential window is constructed via an in situ self-assembly method employing RGO-induced flower-like MOF(Ni). Benefiting from the synergistic effect between RGO and MOF(Ni), the interfacial interactions are effectively improved, and the contact area with the electrolyte is enhanced, which increases the ion transfer kinetics and overall electrochemical performance. The MOF(Ni)@RGO electrode exhibits a specific capacitance of 1267.73 F g-1 at a current density of 1 A g-1. Crucially, the assembled MOF(Ni)@RGO//BC with a broad potential window and good stability employing a MOF(Ni)@RGO anode and biomass carbon cathode, combined with a 2 M PVA-KOH gel-electrolyte, achieves a maximum energy density of 70.16 Wh kg-1 at a power density of 2200.09 W kg-1, outperforming most reported supercapacitors. This hybrid supercapacitor exhibits excellent stability and high energy density, providing a novel strategy for further large-scale applications.

Multifunctional-regions integrated with Mn-Co-Ni ternary hydroxides as self-assembled electrodes for high-performance hybrid supercapacitors

High-performance supercapacitors require elaborate design for electroactive materials with hierarchical structure and multiple components. In the present work, hierarchical nanoarrays composed of MnCoNi LDH@CoNi LDH (MCNL@CNL) with enoki-mushroom-like structure were constructed by integrating the structural regions with complementary functions. The self-assembled electrodes were fabricated upon MCNL@CNL with MnCo LDH@ZIF-67 as precursor and nickel foam as supporter, which achieved a specific capacitance of 2126.7 F/g at 0.5 A/g. The assembled hybrid supercapacitor exhibited the maximum energy density and power density of 51.4 Wh/kg and 7500 W/kg within the voltage range of 0–1.5 V, respectively, and it provided cycling stability with high capacitance retention (104.1%) and Coulombic efficiency (101.1%) after 10,000 cycles. Based on the characterizations results, MCNL@CNL electrode endowed with fast mass transfer, high conductivity and rich electroactive sites was produced, and its induced synergy effect facilitated charge transfer and promoted specific capacitance. Moreover, the hierarchical structure and rough surface of the fabricated MCNL@CNL accelerated the ions/electrons diffusion, and the cross-growing nanosheets on the surface enhanced the affinity. This work provides a novel approach to designing and fabricating self-assembled electrodes with high-performance and lifetime for supercapacitors.

Ag-integrated mixed metallic Co-Fe-Ni-Mn hydroxide composite as advanced electrode for high-performance hybrid supercapacitors

Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices. In this regard, silver (Ag) has attracted great attention in the design of efficient electrodes. Inspired by the house/building process, which means electing the right land, it lays a strong foundation and building essential columns for a complex structure. Herein, we report the construction of multifaceted heterostructure cobalt-iron hydroxide (CFOH) nanowires (NWs)@nickel cobalt manganese hydroxides and/or hydrate (NCMOH) nanosheets (NSs) on the Ag-deposited nickel foam and carbon cloth (i.e., Ag/NF and Ag/CC) substrates. Moreover, the formation and charge storage mechanism of Ag are described, and these contribute to good conductive and redox chemistry features. The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance. The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9 µA h cm−2 at 5 mA cm−2. Moreover, as-assembled hybrid cell based on NF (HC/NF) device exhibited remarkable areal capacity value of 1.82 mA h cm−2 at 5 mA cm−2 with excellent rate capability of 74.77% even at 70 mA cm−2 Furthermore, HC/NF device achieved maximum energy and power densities of 1.39 mW h cm−2 and 42.35 mW cm−2, respectively. To verify practical applicability, both devices were also tested to serve as a self-charging station for various portable electronic devices.

Impact of Co-doping on the microstructural and electrochemical features of mesoporous 3D oval–shaped Ni3-xCoxV2O8 electrodes for high-performance hybrid supercapacitors

Transition metal vanadates have sparked much attention as positive electrode materials for supercapacitors; nevertheless, their poor electronic conductivity, low electroactive sites, and sluggish charge transfer kinetics continue to be problematic. Herein, we incorporate Co dopants in nickel vanadates (NCV) and successfully tailor porous 3D oval-shaped particles using hydrothermal synthesis at 210 °C for 12 h. The interconnected particles, as well as the porous nature of each oval-shaped particle, provide high accessibility to active species and improve charge transfer kinetics. Additionally, the incorporation of cobalt dopants improves electronic conductivity and enriches redox chemistry. As a consequence, NCV delivered a specific capacitance of 391/376 F/g at 0.5/1 A/g current density, with capacitance retention of 98.6 % after 8000 cycles, indicating outstanding cycling stability. Moreover, the micro-spherical layered-structured BiOBr electrode was chosen for the negative electrode and demonstrated a specific capacitance of 132 F/g at a current density of 1 A g−1, in the potential window of −1 to +0 V. Furthermore, the solid-state Ni3-xCoxV2O8//BiOBr hybrid supercapacitor device demonstrated 118 F/g specific capacitance, 25.5 Wh kg−1 energy density, and exceptional cycle stability (85.9 % capacitance preserved after 10,000 cycles).

Unveiling the redox electrochemistry of 1D, urchin-like vanadium sulfide electrodes for high-performance hybrid supercapacitors

Exploring novel versatile electrode materials with outstanding electrochemical performance is the key to the development of advanced energy conversion and storage devices. In this work, we aim to construct new-fangled one-dimensional (1D) quasi-layered patronite vanadium tetrasulfide (VS4) nanostructures by using different sulfur sources, namely thiourea, thioacetamide, and L-cysteine through an ethyleneaminetetraacetic-acid (EDTA)-mediated solvothermal process. The as-prepared VS4 exhibits several unique morphologies such as urchin, fluffy nanoflower, and polyhedron with appropriate surface areas. Among the prepared nanostructures, the VS4-1@NF nanostructure exhibited excellent electrochemical properties in 6 M KOH solution, and we explored its redox electrochemistry in detail. The as-prepared VS4-1@NF electrode exhibited battery-type redox characteristics with the highest capacity of 280 C g−1 in a three-electrode assembly. Moreover, it offered a capacity of 123 F g−1 in a hybrid two-electrode set-up at 1 A g−1 with the highest specific energy and specific power of 38.5 W h kg−1 and 750 W kg−1, respectively. Furthermore, to ensure the practical applicability and real-world performance of the prepared hybrid AC@NF//VS4-1@NF cell, we performed a cycling stability test with more than 5,000 galvanostatic charge–discharge cycles at 2 A g−1, and the cell retained around 84.7% of its capacitance even after 5,000 cycles with a CE of 96.1%.

Assembly of Metal-Organic Frameworks on Transition Metal Phosphides as Self-Supported Electrodes for High-Performance Hybrid Supercapacitors.

In this work, the composite electrode composed of metal-organic frameworks and transition metal phosphides is first assembled on the nickel foam substrate. The as-prepared NiCo-MOF-74@Ni12P5/NF exhibits excellent performances with ultrahigh specific capacitance (12.8 F/cm2 at 1 mA/cm2), stable charge-discharge rate (82.8%), and excellent cycling stability (reserve 73.90% after 5000 charge and discharge cycles at 30 mA/cm2), which are better than those of NiCo-MOF-74@NF without phosphating treatment of nickel foam. The corresponding hybrid supercapacitor (SC) device (NiCo-MOF-74@Ni12P5/NF//AC) delivers high storage capability (44.33 W·h/kg at 800 W/kg) and distinguished operating durability (83.04% after 5000 cycles). In addition, an all-solid-state hybrid SC successfully lit the LED for more than 2 min, which means that there is viable potential for practical applications in energy storage. The improved electrical properties are mainly due to the 3D heterostructure, the positive cooperative binding of nickel and cobalt elements, and the excellent electrical conductivity of the phosphide. As a result, this study proves the possibility of practical applications of NiCo-MOF-74@Ni12P5/NF electrodes for energy storage in hybrid SCs.

Polypyrrole-Assisted Ag Doping Strategy to Boost Co(OH)2 Nanosheets on Ni Foam as a Novel Electrode for High-Performance Hybrid Supercapacitors.

Battery-type electrode materials have attracted much attention as efficient and unique types of materials for hybrid battery supercapacitors due to their multiple redox states and excellent electrical conductivity. Designing composites with high chemical and electrochemical stabilities is beneficial for improving the energy storage capability of battery-type electrode materials. We report on an interfacial engineering strategy to improve the energy storage performance of a Co(OH)2-based battery-type material by constructing polypyrrole-assisted and Ag-doped (Ag-doped@Co(OH)2@polypyrrole) nanosheets (NSs) on a Ni foam using a hydrothermal process that provides richer electroactive sites, efficient charge transportation, and an excellent mechanical stability. Physical characterization results revealed that the subsequent decoration of Ag nanoparticles on Co(OH)2 nanoparticles offered an efficient electrical conductivity as well as a reduced interface adsorption energy of OH- in Co(OH)2 nanoparticles as compared to Co(OH)2@polypyrrole-assisted nanoparticles without Ag particles. The heterogeneous interface of the Ag-doped@Co(OH)2@polypyrrole composite exhibited a high specific capacity of 291.2 mAh g-1 at a current density of 2 A g-1, and showed a good cycling stability after 5000 cycles at 5 A g-1. The specific capacity of the doped electrode was enhanced approximately two-fold compared to that of the pure electrode. Thus, the fabricated Ag-doped@Co(OH)2@polypyrrole nanostructured electrodes can be a potential candidate for fabricating low-cost and high-performance energy storage supercapacitor devices.

Facile solvothermal synthesis of Co1−xS@CNTs/AC nanocomposite as integrated electrode for high-performance hybrid supercapacitors

Transition metal sulfides are considered attractive electrode materials for energy storage and conversion devices due to their excellent electrochemical activity, especially for cobalt-based sulfide with low-cost, high stability and high specific capacity. Herein, we successfully synthesized a novel nanocomposite of carbon nanotube and activated carbon co-modified non-stoichiometric cobalt sulfide (Co1−xS@CNTs/AC) by a facile solvothermal method. Benefiting from the positive effects of CNTs and AC materials on the growth and nucleation of Co1−xS materials, as well as the construction of carbon materials that facilitate fast ion/electron diffusion and transport channels, the as-fabricated optimal Co1−xS@CNTs/AC electrode exhibits a high specific capacitance of 656.51 F g−1 at 0.6 A g−1 and an excellent rate capability, showing significantly better electrochemical properties than bare Co1−xS, Co1−xS@CNTs, and Co1−xS@AC electrodes. Besides, the assembled Co1−xS@CNTs/AC//AC hybrid supercapacitor delivers an excellent energy density of 20.50 Wh kg−1 at a power density of 241.26 W kg−1, and a satisfactory cycling stability of 95.96% capacitance retention after 16,000 cycles at 80 mV s−1. These excellent electrochemical properties demonstrate that the integrated electrode material modified with carbon material is a promising candidate for desiring high-performance green energy storage devices.

Rational design of Cu-doped Co3O4@carbon nanocomposite and agriculture crop-waste derived activated carbon for high-performance hybrid supercapacitors

Development of structurally stable transition metal-oxides and cost-effective biomass-based carbon materials have attracted considerable attention in the fabrication of hybrid supercapacitors. In this work, we designed spinal copper-doped cobalt oxide (Cu-Co3O4) nanoboxes decorated functionalized-carbon nanotubes (f-CNTs) as hybrid redox-type material and agriculture crop-waste derived mesoporous activated carbon as capacitive-type electrode for high-performance hybrid supercapacitors. Structural properties reveal that the Cu-Co3O4has a cubic spinel structure and Raman spectra results confirm the presence of f-CNTs. The hybrid composite material demonstrates superior redox behavior with excellent structural durability. The hybrid electrodes exhibit maximum specific capacity of 130.7 mAh g−1 at 0.5 A g−1 with 86.7 % capacitance retention over 10,000 cycles. Besides, the crop waste-derived activated carbon demonstrates high surface area (1549 m2g-1), mesoporous characteristics and excellent capacitive behavior. The high voltage hybrid supercapacitor is further fabricated with Cu-Co3O4@F-CNTs as battery-type and biomass-derived activated carbon as capacitive-type electrodes, which demonstrate high energy density of 30.8 Wh kg−1 at 5972 W kg -1 power density. The augmented results indicate that the hybrid composites with biomass-derived carbon materials pave the way for design of eco-friendly energy storage applications.

Facile growth of nickel foam-supported MnCo2O4.5 porous nanowires as binder-free electrodes for high-performance hybrid supercapacitors

In this work, porous MnCo2O4.5 nanowires (NWs) were directly grown on nickel foam (NF) via an initial hydrothermal route with an extra annealing treatment of precursor. Another comparative experiment was conducted with a lower amount of urea to obtain particle-based MnCo2O4.5 films. These binder-free MnCo2O4.5@NF electrodes exhibited battery-type electro-chemical response with superior electro-chemical performance. Especially, the MnCo2O4.5-NWs@NF delivered a huge capacity of 288.47 C g−1 at 1 A g−1 and 78.07% of capacity retention at 10 A g−1. Moreover, a hybrid supercapacitor (HSC) that was assembled using activated carbon (AC) as an anode could operate over a voltage of 1.7 V. The MnCo2O4.5-NWs@NF//AC HSC delivered an energy density of up to 29.57 W h kg−1 at the power density of 914.28 W kg−1, and it could still hold 20.82 W h kg−1 since the power density was improved to 8.24 kW kg−1. In addition, both these MnCo2O4.5 NWs- and films-based HSCs showed an impressive cyclic stability over continuous 6000 cycles at a high current density of 6 A g−1, but only a little capacity decay was observed. Such extraordinary electro-chemical performance makes the binder-free MnCo2O4.5-NWs@NF electrode material promising and very feasible to be applied for electro-chemical energy storage devices such as batteries, supercapacitors, and so on.

Unlocking the potential of a novel hierarchical hybrid (Ni–Co)Se2@NiMoO4@rGO–NF core–shell electrode for high-performance hybrid supercapacitors

Nano-hybridization of a core–shell structure integrating a transition metal selenide with oxides results high-capacity electrode materials for energy storage devices thanks to the ample electroactive sites and relatively high electronic conductivity.

Engineering hierarchical porous ternary Co-Mn-Cu-S nanodisk arrays for ultra-high-capacity hybrid supercapacitors

Transition-metal sulfides have been recognized as one of the promising electrodes for high-performance hybrid supercapacitors (HSCs). However, the poor rate performance and short cycle life heavily impede their practical applications. Herein, an advanced electrode based on hierarchical porous cobalt-manganese-copper sulfide nanodisk arrays (Co-Mn-Cu-S HPNDAs) on Ni foam is fabricated for high-capacity HSCs, using metal-organic frameworks as the self-sacrificial template. The synergistic effects of ternary Co-Mn-Cu sulfides and the hierarchical porous structure endow the as-obtained electrode with fast redox reaction kinetics. As expected, the resultant Co-Mn-Cu-S HPNDAs electrode delivers an ultrahigh specific capacity of 536.8 mAh g−1 (3865 F g−1) at 2 A g−1 with a superb rate performance of 63% capacity retention at 30 A g−1. Remarkably, an energy density of 63.8 W h kg−1 at a power density of 743 W kg−1 with a long cycle life is also achieved with the quasi-solid-state Co-Mn-Cu-S HPNDAs//ZIF-8-derived carbon HSC. This work offers a new pathway to fabricate high-performance multiple transition-metal-sulfide-based electrode materials for energy storage devices.

Controllable nitrogen-doped carbon layers coated on NiCoO2 as electrodes for high-performance hybrid supercapacitors

Controllable nitrogen-doped carbon layers coated on NiCoO2 (NiCoO2@N-C) as anode materials are successfully synthesised by facile hydrothermal method and post-annealing treatment. Benefiting from the synergistic merits of carbon and nitrogen, the as-synthesised NiCoO2@N-C delivered an excellent capacitance of 1000 F g−1 at 1 A g−1 and a high specific capacitance of 491 F g−1 at 50 A g−1. After 5000 cycles at 10 A g−1, the cyclic stability remains 91% of the initial capacitance. Moreover, the assembled asymmetric supercapacitor exhibits a high energy density of 45.9 Wh kg−1 at a power density of 375 W kg−1. The NiCoO2@N-C hybrid nanostructure was investigated by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques. In situ X-ray absorption near edge structure (XANES) spectroscopy was used to track the changes of NiCoO2@N-C electrode under electrochemical working conditions and confirmed that Ni had more significant electrochemical activity than Co. These findings provide new insights into the role of heteroatom doping for high-performance supercapacitors in future applications.

Tin-based metal-phosphine complexes nanoparticles as long-cycle life electrodes for high-performance hybrid supercapacitors

New tin-based metal-phosphine complexes of [Sn(OH)4(PPh3)2] and [Sn(OH)2(PPh3)2] have been successfully synthesized and used as supercapacitor electrodes for the first time, exhibiting a high specific capacitance, a good rate capability, and an excellent cycling stability. The specific capacitances (highest specific capacitance for tin-based materials) of 1204F g−1 and 764F g−1 for two samples at a current density of 1 A g−1 in 6 M KOH can respectively be achieved, and their capacitance retention remained at 95.1% and 89.2% even after 15,000 cycles at a current density of 10 A g−1. Furthermore, a flexible quasi-solid-state asymmetric supercapacitor composed of Sn(OH)2(PPh3)2 and activated carbon was assembled and exhibited a specific capacitance of 290.6 mF cm−2 at a current density of 1 mA cm−2. More importantly, this device also displayed excellent cyclic stability of ∼100% for 1800 cycles during the galvanostatic charge/discharge process at 5 mF cm−2.

Construction of core-shell Ni@Ni3S2@NiCo2O4 nanoflakes as advanced electrodes for high-performance hybrid supercapacitors

A universal strategy was used to synthesize the core-shell structure Ni@Ni3S2@NiCo2O4 nanoflakes. As wished, benefiting from the core-shell structure of nanoflakes, the as-synthesized Ni@Ni3S2@NiCo2O4 electrode materials show excellent electrochemical performance. Furthermore, the effect of ethylenediamine on the electrochemical performances of the Ni@Ni3S2@NiCo2O4 nanoflakes was studied. In a three-electrode system, the specific capacitance achieves 13.4 F cm−2 at a current density of 1 mA cm−2 and even 11.7 F cm−2 at 10 mA cm−2. Moreover, the fabricated hybrid supercapacitor was assembled using Ni@Ni3S2@NiCo2O4 as a positive electrode, the activated carbon (AC) as a negative electrode, and KOH as an electrolyte, respectively. The assembled device delivers an energy density of 57 Wh∙kg−1 at a power density of 3700 W kg−1 and good cycling stability (82% capacitance retention after 8000 cycles), demonstrating its excellent energy storage property in supercapacitor.

Architectural Ni3Se2 nanosheet-on-nanoforests as free-standing electrodes for high-performance hybrid supercapacitors

A unique electrode architecture consisting of Ni3Se2 nanosheet-on-Ni3Se2-nanoforests grown on nickel foam was obtained by a simple one-step solvothermal method, which subsequently used as a free-standing electrode for supercapacitor. The Ni3Se2 exhibited a high capacity of up to 600 μAh cm−2 at 3 mA cm−2, excellent rate capability and cycling stability at high cycling rates. Impressively, the optimized hybrid supercapacitor containing Ni3Se2 cathode still released 94.4% of initial capacity for 505 μAh cm−2 after 6000 cycles at 20 mA cm−2. The results suggest that the Ni3Se2 nanoforests developed electrode has great potential for practical applications in hybrid supercapacitors.

A High-Energy-Density Hybrid Supercapacitor with P-Ni(OH)2 @Co(OH)2 Core-Shell Heterostructure and Fe2 O3 Nanoneedle Arrays as Advanced Integrated Electrodes.

Transition metal hydro/oxides (TMH/Os) are treated as the most promising alternative supercapacitor electrodes thanks to their high theoretical capacitance due to the various oxidation states and abundant cheap resources of TMH/Os. However, the poor conductivity and logy reaction kinetics of TMH/Os severely restrict their practical application. Herein, hierarchical core-shell P-Ni(OH)2 @Co(OH)2 micro/nanostructures are in situ grown on conductive Ni foam (P-Ni(OH)2 @Co(OH)2 /NF) through a facile stepwise hydrothermal process. The unique heterostructure composed of P-Ni(OH)2 rods and Co(OH)2 nanoflakes boost the charge transportation and provide abundant active sites when used as the intergrated cathode for supercapacitors. It delivers an ultrahigh areal specific capacitance of 4.4 C cm-2 at 1 mA cm-2 and the capacitance can maintain 91% after 10 000 cycles, showing an ultralong cycle life. Additionally, a hybrid supercapacitor composed with P-Ni(OH)2 @Co(OH)2 /NF cathode and Fe2 O3 /CC anode shows a wider voltage window of 1.6 V, a remarkable energy density of 0.21 mWh cm-2 at the power density of 0.8 mW cm-2 , and outstanding cycling stability with about 81% capacitance retention after 5000 cycles. This innovative study not only supplies a newfashioned electronic apparatus with high-energy density and cycling stability but offers a fresh reference and enlightenment for synthesizing advanced integrated electrodes for high-performance hybrid supercapacitors.

Facile synthesis of morphology-controllable NiCo2S4 arrays on activated carbon textile as high-performance binder-free supercapacitor electrode

Binder-free electrodes provide great opportunities for the development of high-performance energy devices due to the absence of insulating and inactive binders. In this paper, NiCo2S4 arrays with attractive nanostructures were directly grown on activated carbon textile (ACT) by a facile one-pot hydrothermal method to develop a self-supported binder-free electrode. The nanostructures can be tuned from nanorods to nanosheets by simply controlling the concentration of the sulfur source. Both arrays exhibited battery-type behavior of the positive electrode, where the nanosheets arrays with relatively higher capacity of 183.2 mA h g−1 at 2 mA cm-2 and better cycling stability of 82.6 % capacitance retention after 1000 cycles was employed in an asymmetric supercapacitor (ASC) as positive electrode. The ASC exhibited excellent rate capability with the maximum specific energy of 56.2 Wh/kg and the specific power of 632.7 W/kg at the current density of 4 mA/cm2. The presented results are believed to be helpful to the design and application of promising flexible binder-free electrode for high-performance hybrid supercapacitors.

Nitrogen-doped carbon integrated nickel–cobalt metal phosphide marigold flowers as a high capacity electrode for hybrid supercapacitors

The fabrication of advanced MOF-derived multicomponent NiCoP/NC marigold flowers electrode for high-performance hybrid supercapacitors.

ZIF-67-assisted construction of hollow core/shell cactus-like MnNiCo trimetal electrodes and Co, N dual-doped carbon electrodes for high-performance hybrid supercapacitors

.A novel hybrid supercapacitor of Ni-CCH@MnNiCo-OH//ZIF-67-C-KOH was successfully fabricated with promising electrochemical storage properties.