Advanced Electrode Materials For Supercapacitors Research Articles

Rational design of 2D/1D ZnCo-LDH hierarchical structure with high rate performance as advanced symmetric supercapacitors

Hierarchical microstructures of electrode materials for supercapacitors have attracted strong attention owing to the enlarged surface area, fast charge transportation and enhanced volume expansion. All these advantages of hierarchical structures are available for facilitating the electrochemical performances and stability of electrode materials for advanced supercapacitors. However, few reports focused on the development of transition metal-based homogeneous 2D/1D hierarchical structures use the same material. Herein, the ZnCo-LDH with 3D hierarchical microstructure was self-assembled with 1D nanoneedles and 2D nanosheets that in situ synthesized on Ni foam through a simple and effective strategy. The optimal sample (ZnCo-LDH-2) exhibited the ultra-high specific capacitance of 3871.2 F g −1 at 1 A g −1 and excellent cycle life span (capacitance retention of 87.5% after 6000 cycles at 5 A g−1). Particularly, the current density was as high as 100 A g−1, the specific capacitance of ZnCo-LDH-2 still remained 1526 F g−1. Moreover, the symmetric supercapacitor (SSC) fabricated with ZnCo-LDH-2 showed the maximum energy density of 40.3 Wh kg−1 and power density of 15.08 kW kg−1.

Cu-Fe based oxides and selenides as advanced electrode materials for high performance symmetric supercapacitors

Copper-based chalcogenides are becoming popular as electrode materials for electrochemical energy storage. Herein, we report the electrochemical energy storage performance of CuFeO2 and CuFeSe2 synthesized via facile solvothermal method. At 1 A g−1, the symmetric supercapacitors based on CuFeO2 electrodes and CuFeSe2 electrodes exhibit specific capacitance values of 128 F g−1 and 260 F g−1, respectively. Further, CuFeO2 and CuFeSe2 electrodes demonstrate incredible specific energy values of 18 Wh kg−1 and 36 Wh kg−1, respectively, at a specific power of 1 kW kg−1. Moreover, both CuFeO2 and CuFeSe2 electroactive materials result in enhanced capacitive retention of 96% and 97%, respectively, for 10,000 charge-discharge cycles. The remarkable electrochemical energy storage performance of both CuFeO2 and CuFeSe2 materials make them potential aspirants for future energy storage systems.

表面氧化构建PPy@VNO/NG核壳结构作为长寿命超级电容器负极材料

Vanadium nitride (VN)-based materials have been investigated as negative electrode materials for supercapacitors (SCs) owing to their high theoretical capacitances and suitable negative potential windows. However, viable VN-based negative electrode materials suffer from irreversible electrochemical oxidation of the soluble vanadium species, leading to rapid capacitance fading when operated in aqueous electrolytes. Developing a versatile approach to enhance the stability of VN in aqueous electrolytes is still a challenge. Here, an interface engineering strategy is developed to intentionally introduce surface nanolayers of vanadium oxides (VOX) as a reactive template on the VN surface to formulate well-designed polypyrrole@VNO (Ppy@VNO) core-shell nanowires (NWs) incorporated into a 3D porous N-doped graphene (NG) hybrid aerogel as a durable negative electrode for SCs. Experimental and theoretical investigations reveal that the in-situ constructed Ppy@VNO core-shell host can offer more efficient pathways for rapid electron/ion transport and accessible electroactive sites. Most importantly, a reversible surface redox reaction is realized through the transformation of the valence state of V, and a long cyclic stability is achieved. The Ppy@VNO/NG hybrid aerogel can deliver a high specific capacitance of 650 F g−1 at 1 A g−1 with approximately 70.7% capacitance retention (up to the twenty fold current density), and an excellent cycling stability without any capacitance de cay after 10,000 cycles at both low and high current densities (1 and 10 A g−1, respectively). This work paves the way for the development of advanced electrode materials for SCs.

Synthesis of nitrogen-doped porous carbon and partial poly (2, 2′-dithiodianiline) composite as advanced supercapacitor electrode materials

Composited materials (NC/PDTDA) of nitrogen-doped porous carbon (NC) and partial poly (2, 2′-dithiodianiline) (PDTDA) have been successfully synthesized by in-situ polymerization and can be utilized in alkaline electrolytes as electrodes for supercapacitors. The physiochemical properties of NC/PDTDA composites materials are characterized by field emission scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, Raman spectrum, X-ray electron spectrum, and X-ray diffraction. In addition, the electrochemical properties of NC/PDTDA composites materials are tested in 3 M KOH aqueous solution with a representative three-electrode system. It shows the highest specific capacitance when the mass ratio of NC to PDTDA is 1:2 (NC/PDTDA-2), and the specific capacitance is 490.5 F/g at a current density of 1 A/g. More significantly, the asymmetric supercapacitor is also assembled with an extended operating voltage window of 1.4 V in PAM-PVA- KOH electrolyte. It exhibits an energy density of 13.49 Wh/Kg at a power density of 699.8 W/Kg.

Induced conducting energy-levels in a boron nitride nano-framework for asymmetric supercapacitors in high charge-mobility ionic electrolytes

Boron nitride's (BN) large band gap does not permit carrier transport at ambient conditions. We show that BN sheets can be exfoliated by functionalization with oxy-groups to introduce additional acceptor and donor energy levels appropriate for energy storage devices. Further, the incorporation of heteroatoms into transition metal sulfides enhances capacitance via Faradic redox reactions and their cyclic stability. The functionalized boron nitride (mK-BN) and Carbon Nanotubes (CNTs) are intertwined with a Zn-doped Cadmium-Sulfide (Zn–CdS) nanostructure to increase the surface area-charge storage. In a supercapacitor application, Zn–CdS/mK-BN/CNT exhibits a 787 F/g specific capacitance (SC) in an aqueous (aq.) electrolyte. Further, the Zn–CdS/mK-BN/CNT was deployed as a cathode material in an asymmetric supercapacitor device (ASC) coupled with an ionic electrolyte (IE), (NHEt3)+(NO3)−, offered a SC of 173 F/g with an approximate 99% stability due to the enhanced charge mobility. The reported functionalization of BN induces additional energy levels making the material ideal for energy storage devices and will directly impact the next-generation of advanced supercapacitor electrode materials.

Hierarchically activated porous carbon derived from zinc-based fluorine containing metal-organic framework as extremely high specific capacitance and rate performance electrode material for advanced supercapacitors

In this work, a hierarchically activated porous carbon (APC) was synthesized using fluorine-containing metal-organic framework via facile combined carbonization and KOH activation treatments. The influences of activation conditions on the surface structures and electrochemical performance of APC were systematically studied. Afterwards, the electrochemical responses of APC electrode were further assessed from the cyclic voltammetry and galvanostatic charge-discharge examinations by 6 M KOH electrolyte. The as-obtained APC electrode delivered the high specific capacitances of 540.8 and 280 F g−1 at 1 and 500 A g−1, correspondingly with superior capacitance retention of 94% after 250,000 cycles even at 100 A g−1, which is showing that its outstanding capacitance, remarkable rate capacity, and very-long cyclic life. Furthermore, the as-assembled APC-based symmetrical supercapacitor offers a superb energy density of 19 Wh kg−1 at 182 W kg−1, indicating its large-scale application. Thus, this work proposes a potential route to synthesize highly efficient porous carbon material for the future development of energy storage systems.

Enhanced pseudocapacitive performance of MoS2 by introduction of both N-GQDs and HCNT for flexible supercapacitors

In this work, we report a strategy for enhancing the pseudocapacitive performance of MoS2 materials by the introduction of nitrogen-doped graphene quantum dots (N-GQDs) and helical carbon tubes (HCNT). By a simple hydrothermal process, the hybrid composite (MoS2, N-GQDs and HCNT) were coated on the carbon cloth (CC) without any binders, which can be directly used as advanced electrode material for high-performance solid-state flexible supercapacitors. In this hybrid structure, N-GQDs are inserted between the layers of MoS2 nanosheets, which induce and expose more active sites for pseudocapacitance contributions in MoS2 electrode materials. Meanwhile, HCNT acts as electrically conducting bridge for enhancing the electrical conductivity of MoS2 nanosheets and speeding up transport of electronic. As results, the hybrid composite (MoS2, N-GQDs and HCNT) show higher capacitive performance than pure MoS2. The specific capacitance of hybrid composite is high up to 3360 mF cm−2. Further, the assembled solid-state flexible supercapacitor shows high specific capacitance of 1893 mF cm−2, outstanding cycle life (capacitance retention of 86% after 2500 cycles), good mechanical stability and great flexibility. Our work provides a reference for the preparation of MoS2 composites with high supercapacitive performance.

Microwave assisted growth of MnO2 on biomass carbon for advanced supercapacitor electrode materials

Microwave assisted growth of MnO2 on biomass carbon for advanced supercapacitor electrode materials

Rational design of flower-like Co-Zn LDH@Co(H2PO4)2 heterojunctions as advanced electrode materials for supercapacitors.

Layered double hydroxides (LDHs) with high theoretical specific capacity have been considered as one of the most promising candidates for high-performance supercapacitors. However, the low electronic conductivity and insufficient active sites hinder the further large-scale application of bulk LDHs. Here, we successfully synthesized heterostructured Co-Zn LDH@Co(H2PO4)2 nanoflowers by a simple hydrothermal method. As the amount of Co(H2PO4)2 in the whole heterostructure increases, the nanosheets steadily evolve into nanoflowers with a high surface area, providing more electrochemically active sites. Moreover, the built-in electric field formed between Co-Zn LDH and Co(H2PO4)2 improves the conductivity of the composite electrode. As a result, the as-prepared Co-Zn LDH@Co(H2PO4)2 shows a high specific capacity of 919 C g-1 at a current density of 1 A g-1. A hybrid supercapacitor (HSC) with activated carbon (AC) as the negative electrode and Co-Zn LDH@Co(H2PO4)2 as the positive electrode delivers an energy density of 30.4 W h kg-1 at a power density of 400 W kg-1, and 95.3% of the initial capacity is retained after 5000 cycles. This study provides a novel synthesis strategy for constructing heterojunctions to enhance the energy storage properties of LDH-based materials.

Fabrication of nitrogen-doped hierarchical porous carbons from Sargassum as advanced electrode materials for supercapacitors

The as-synthesized N0.67@SAC showed a large specific surface area of 2928.78 m2 g−1 and high capacitance of 481 F g−1.

High specific capacitance of a 3D-metal–organic framework-confined growth in CoMn2O4 nanostars as advanced supercapacitor electrode materials

An hybrid supercapacitor was fabricated on Co(ii)-TMU-63#30%CoMn2O4 nanocomposites (as the positive electrode) and AC (as the negative electrode), resulting in the high energy density of 38.54 W h kg−1 and power density of 2312.4 W kg−1.

Facile synthesis of strontium ferrite nanorods/graphene composites as advanced electrode materials for supercapacitors

The exploration of efficient and stable electrode materials is important for supercapacitors. Composite electrode materials are promising candidates for supercapacitors since single component materials cannot satisfy the dual needs of high energy density and power density. In this study, uniform strontium ferrite nanorods are grown on graphene by a facile surfactant assisted hydrothermal method. The resultant SrFe12O19 nanorods/graphene (SrFe12O19 NR/G) composites combine the merits of both SrFe12O19 and graphene, and the SrFe12O19 NR/G based supercapacitors exhibit specific capacitances of 681.2 and 450.9 F g−1 at 1 and 20 A g−1, respectively, and 95.5% of capacitance retention after 10,000 cycles at 1 A g−1. Moreover, they exhibit outstanding energy density and power density characteristics (47.3 Wh kg−1 at 500.9 W kg−1 and 31.3 Wh kg−1 at 10247.7 W kg−1). In addition, the influence of component ratio on the electrochemical performances of SrFe12O19 NR/G composites is thoroughly studied. Finally, the energy storage behavior and mechanism of as-obtained SrFe12O19 NR/G composites are investigated to further understand their enhanced capacitive performances. This work not only provides a new supercapacitor electrode material, but also offers an idea that can be used for the construction of composite electrode materials.

Fabrication of hierarchical Zn–Ni–Co–S nanowire arrays and graphitic carbon nitride/graphene for solid-state asymmetric supercapacitors

The rational design and subsequent growth of apposite nanostructured transition metal sulfide on conductive scaffold with auspicious morphology to produce an advanced electrode material for supercapacitors is highly desirable to boost the electrochemical performance. Herein, a simplistic two-step strategy is designed to grow 3D-networked and mesoporous Zn–Ni–Co–S nanowire-like arrays (NWAs) on a Ni-foam scaffold, which includes the hydrothermal growth of Zn–Ni–Co-based hydroxyl precursor, followed by an effective sulfidation process. When employed as a free-standing electrode for supercapacitors, Zn–Ni–Co–S NWAs electrode delivers a superb capacity of 418.2 mA h g−1 at 4.6 mA cm−2, good rate capability (233.3 mA h g−1 at 50 mA cm−2), and long cycle life (~89% of capacity retained after 10,000 cycles). Furthermore, a solid-state asymmetric supercapacitor device was constructed based on Zn–Ni–Co-S NWAs as cathode and graphitic carbon nitride/graphene as anode materials, achieves a cell capacity of 110.7 mA h g−1 at 5 mA cm−2, superior capacity retention (54% at 75 mA cm−2) and superb cyclic performance (93% after 10,000 cycles). The device delivers a superb energy density of 88.6 W h kg−1 at a power density of 419.4 W kg−1, and upholds an energy density of 47.6 W h kg−1 at a high power density of 7048.4 W kg−1.

Simple synthesis of honeysuckle-like CuCo2O4/CuO composites as a battery type electrode material for high-performance hybrid supercapacitors

In this paper, porous CuCo2O4/CuO composites with novel honeysuckle-like shape (CuCo2O4/CuO HCs) have been prepared for the first time by a simple hydrothermal method and followed with an additional annealing process in air. The unique CuCo2O4/CuO HCs consisted of dense and slender petals with length of 1.3–1.5 μm and width of about 50 nm, and possessed a specific surface area of 36.09 m2 g−1 with main pore size distribution at 10.63 nm. When used as the electrode materials for supercapacitors, the CuCo2O4/CuO HCs exhibited excellent electrochemical performances with a high specific capacity of 350.69 C g−1 at 1 A g−1, a rate capability of 78.6% at 10 A g−1, and 96.2% capacity retention after 5000 cycles at a current density of 5 A g−1. In addition, a hybrid supercapacitor (CuCo2O4/CuO HCs//AC HSC) was assembled using the CuCo2O4/CuO HCs as positive electrode and activated carbon (AC) as negative electrode. The HSC device delivered a specific capacity of 187.85 C g−1 at 1 A g−1 and a superior cycling stability with 104.7% capacity retention after 5000 cycles at 5 A g−1, and possessed a high energy density of 41.76 W h kg−1 at a power density of 800.27 W kg−1. These outstanding electrochemical performances manifested the great potential of CuCo2O4/CuO HCs as a promising battery-type electrode material for the next-generation advanced supercapacitors with high-performance.

In Situ Growth of 2D Ultrathin NiCo2 O4 Nanosheet Arrays on Ni Foam for High Performance and Flexible Solid-State Supercapacitors.

In order to further overcome the shortage of electrodes with additive/binder and modulate the structure of NiCo2 O4 for supercapacitors, ultrathin NiCo2 O4 nanosheet arrays have been in situ grown on Ni foam by optimizing hydrothermal reactions based on crystal growth dynamics. The structure of ultrathin NiCo2 O4 nanosheet arrays can expose more active sites, provide abundant diffusion channels and buffer the stress caused by phase transition during charge-discharge process of supercapacitors. The optimized hydrothermal reactions can provide more ordered crystal orientations by keeping nanosheets on Ni foam completely coming from in situ growth, which will decrease the inner resistance of ultrathin NiCo2 O4 nanosheets and improve the efficiency and kinetics of electrons transfer. By the virtue of such remarkable features, the electrochemical results confirm the rationality of structural modulation and crystal orientations optimization with a drastically enhanced specific capacitance of 2017.8 F g-1 , admirable rate performance of 93.2% and outstanding stability retention of 90.9% after cycling 5000 times. More impressively, the assembled flexible solid-state asymmetric supercapacitor (ASC) shows superior energy density, power density, and high stability. The modification strategy in this paper may throw light on the rational design of new generation advanced electrode materials for high-performance flexible supercapacitors.

Oxygen Vacancy‐Engineered Ti−Mo−Ni Ternary Oxide Nanotubes as Binder‐Free Supercapacitor Electrodes with Exceptional Potential Window

AbstractThe charge storage performance of metal oxides as electrochemical supercapacitor electrodes is limited by their poor conductivity and limited operating potential window. Herein, we report on the oxygen‐vacancy engineering of Ti−Mo−Ni−O nanotubes via hydrogen annealing to boost their capacitive performance. Hydrogen treatment of the nanotubes resulted in 110% increase in specific capacitance as compared to the air‐annealed counterpart with excellent stability over 3700 cycles and an exceptional capacitance retention of 99%. The observed enhancement can be ascribed to the faradaic capacitance contribution from the several redox pairs of Nickel, Molybdenum, and Ti3+. This was further confirmed via the electrochemical impedance spectroscopy measurements, revealing a drastic decrease in the internal resistance upon hydrogen treatment. We hope our demonstrated two‐step interfacial engineering opens a new strategy to design high performance electrode materials for advanced electrochemical supercapacitors.

Core-shell nanostructured ZnO@CoS arrays as advanced electrode materials for high-performance supercapacitors

Cost-effective zinc oxide (ZnO) nanomaterials with high theoretical specific capacity have been regarded as one of the most prospective candidates for high-performance supercapacitor; however, its extensive application is limited by poor active sites and low conductivity, which increase the internal resistance of the electrode and reduce the capacity of the supercapacitor. Herein, we carried out a simple two-step method to synthesize a core-shell structure of ZnO core nanosheets enclosed in a shell of CoS (ZnO@CoS). This well-designed structure improves the electrical conductivity of the electrode, and the large specific surface area provides sufficient active sites. The as-prepared ZnO@CoS electrode exhibits a high specific capacity of 898.9 C g−1 at a current density of 3 mA cm−2, which is 1.47 and 1.70 times higher than those of ZnO and ZnO precursor. Moreover, the assembled asymmetric supercapacitor (ASC) with active carbon (AC) as the negative electrode and ZnO@CoS as the positive electrode displays an energy density of 45.2 Wh kg−1 at a power density of 1039.1 W kg−1 as well as achieves excellent specific capacity of 2438 mC cm−2. The ASC also shows superior cycleability with 107% capacity retention after 11,000 cycles.

Laser-induced nanofibrous titania film electrode: A new approach for energy storage materials

Abstract The research described here proposes a novel use of titanium oxide nanofibrous film as advanced electrode material for high performance supercapacitors. High frequency picosecond laser pulses were employed to generate a film of oxidized Ti on Ti substrate. Physico-chemical characterizations and morphological studies revealed the formation of fibrous TiO2 micro/nano-structures. The electrochemical measurements of the generated nanostructures showed their improved electrochemical properties and proved the feasibility of using laser pulses for fabrication of advanced electrodes with high specific capacitance. Also, our results showed by double laser processing, the average diameter of the generated TiO2 fibers decreased from 300 nm to the range of 60–70 nm. Combination of having higher porosity (smaller fiber diameters) and more oxidized Ti results in better supercapacitance behaviours. These studies demonstrated the usefulness of laser generated nanofibrous film as a novel electrode material for high performance supercapacitors. It can lead to promising methods for fabrication of advanced electrodes with high energy and power density with excellent cyclic stability.

Synthesis of nickel sulfide–graphene oxide composite microflower structures to enhance supercapacitor performance

NixSy in various crystal phases (NiS, NiS2, and Ni3S4) was synthesized on thermally reduced graphene oxide (TRGO) by a one-step hydrothermal process. Microstructures and morphologies of as-prepared NixSy–TRGO composites were characterized. NixSy was formed as microflowers with average size of 1.1–2.3 µm, which grew homogeneously on the curved TRGO nanosheets. Electrochemical performance of NixSy–TRGO was revealed with high specific capacitance of 1602.2 F g−1 at 1 A g−1 and favorable cycling retention of 90.81% after 3000 cycles at 5 A g−1. An asymmetric supercapacitor device based on NixSy–TRGO||TRGO exhibited a superior energy density of 39.78 Wh kg−1 at the power density of 0.75 kW kg−1 with an cycling stability of 91.2% capacitance retention after 3000 cycles. Thus, the as-prepared NixSy–TRGO could be an advanced supercapacitor electrode material.

High-performance pseudo-capacitor energy storage device based on a hollow-structured copper sulfide nanoflower and carbon quantum dot nanocomposite

Transition metal sulfides are widely used in high-performance energy storage equipment due to its excellent electrochemical activity and electrical conductivity. In this study, we introduce a carbon quantum dot (CQD)-doped hollow CuS composite (CuS@CQDs) as a novel electrode material for advanced asymmetric supercapacitors through one-step solvothermal synthesis and an impregnation bonding method. The CuS@CQDs composites with uniform and hierarchical porous architecture possess high specific area and low specific resistance, which can facilitate the transport of electrolytes and electrons. The as-prepared CuS@CQDs-ICM electrode exhibits a maximum specific capacitance of 920.5 F g−1 at a current density of 0.5 A g−1 and an energy density of 44.19 W h kg−1 at a power density of 397.75 W kg−1 with an excellent cycling stability of 92.8% after 10,000 cycles. The satisfactory electrochemical performance can be attributed to the unique nanoflower-like hollow structure of the CuS@CQDs composites and the synergy between CuS and CQDs.