Advanced Supercapacitor Electrodes Research Articles

Conducting polymers/oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth as advanced electrodes for high-performance supercapacitors

The low energy density of supercapacitors (SCs) is one of the main factors restricting their development. WO3 with high theoretical capacitance is an ideal n-type material for anode electrode, but its narrow potential window and low conductivity are not conducive to the application of high-energy-density SCs. Herein, a high electrochemical activity poly(indole-5-carboxylic acid) (P5-ICA) as p-type material wrapping n-type oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth is prepared by hydrothermal method and subsequent electrodeposition method. This adhesive free flexible p/n-type hetero-structural P5-ICA@WO3 vertical nanowire array electrode has a three-dimensional porous nanostructure that not only provides a large surface area, but also promotes the penetration of electrolyte ions and the transmission of electrons. It is found that the P5-ICA@WO3 nanowire array with high areal specific capacitance (1430 mF cm−2 at 4 mA cm−2) and long cycle stability (94 % after 6000 cycles) exhibits a widened electrochemical activity window compared to individual material. The symmetrical SCs assembled using P5-ICA@WO3 can provide a high areal energy density of 137.6 μWh cm−2 at the power density of 1.4 mW cm−2, which is significantly higher than the SCs performance of previously used WO3-based electrode materials.

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.

Homogeneously deposited polyaniline on etched porous carbon cloth towards advanced supercapacitor electrode

Homogeneously deposited polyaniline on etched porous carbon cloth towards advanced supercapacitor electrode

Self-assembled carbon wrapped manganese cobaltite nano-composite with promising electrochemical performance for symmetric and asymmetric supercapacitor device

The growing energy requirements of modern society have led to an intensive search for advanced supercapacitor (SC) electrode materials. Binary transition metal oxides with excellent supercapacitive performance are among the most promising materials. However, the phase transformation of these metal oxides during repeated charging/discharging is a major concern, which depletes their cyclic performance. Coating metal oxides with carbon can provide structural stability to the metal oxide, thereby increasing their cyclic life. In addition, the highly conductive carbon enhances the capacitance of metal oxides by allowing the effective transfer of charges from MnCo2O4 to the current collector. In this study, self-assembled carbon-wrapped MnCo2O4 composite has been prepared through a two-step process involving hydrothermal and solution-mixing processes. The structural/electrochemical performances of the composites have been investigated. The optimized composite offered a maximum capacitance of 626.8 Fg−1 withholding 98 % of capacitance for 6000 cycles. Furthermore, the electrochemical performance of the composite has also been tested in an all-redox symmetric SC (SSC) as well asymmetric (ASC) configuration. In the symmetric cell, 30.2 Whkg−1 of energy is reported for 1.6 kWkg−1 of power. The asymmetric cell with the optimized composite as a cathode and MnO2/Activated carbon as an anode was fabricated. The ASC displayed 45.5 Whkg−1 of energy corresponding to 10 kWkg−1. Three SSCs/ASCs in series illuminated a panel of 39 red-LEDs for 9 and 15 min, respectively. The results suggest the promising performance of such composites for hybrid supercapacitors. Thus, the fabrication of all-redox-type SSCs/ASCs can be a futuristic approach for hybrid storage systems.

Post-treatment of ZIF-67/Ni3S4 Nanoparticle Composites by Metal Ions and Solvent-Assisted Etching as Advanced Electrodes for Supercapacitors

Incorporating metal compound nanoparticles into zeolitic imidazolate frameworks (ZIFs) has emerged as an effective way to solve the low conductivity issue of ZIFs, helping to boost their electrochemical performance. However, the resultant ZIFs/metal compound composites usually lack hierarchical pores, which causes the electrochemical performance to be far below expectations. Here, two rational post-treating strategies, namely, Ni2+/H2O etching and solvent-assisted etching, have been proposed to tailor the structure and composition of ZIF-67/Ni3S4 composite. Especially, Ni2+/H2O etching enables the self-transformation of ZIF-67 to CoNi layered double hydroxide (LDH), while solvent-assisted etching creates hierarchical pores in ZIF-67. After post-treatments, both resultant samples display significant improvements in energy storage capability and cycling lifespan as compared to untreated ZIF-67/Ni3S4 owing to their superior features including the hierarchical pore structure, enhanced pseudocapacitance property, and less internal and charge transfer resistance. The tailoring strategies together with mechanism studied here can provide perspectives and constructive designing knowledge to promote the widespread use of ZIFs or Ni3S4 based advanced electrodes toward high-performance supercapacitors.

Engineering hierarchical honeycomb-wall-like MgP4O11/CoP nanosheets as advanced binder-less electrode for supercapacitors

Herein, Mg/Co(OH)F precursors were constructed by a hydrothermal method using secondary water and anhydrous ethanol in a volume ratio of 3:2 as solvents, followed by sodium hypophosphite and high temperature to yield stable MgP4O11/CoP (MPO/CP) composite electrode materials. The optimized MPO/CP nano-walls exhibited more outstanding energy storage performance compared with the single MgCo2O4/MgO oxide (MCO/MO). Specifically, the fabricated MPO/CP electrodes displayed paramount specific capacitance (1870 Fg−1 formed at 1 Ag−1), high rate retention (72.2% specific capacitance maintained when the current density was ramped up from 1 to 15 Ag−1), and exceptional cycling stability (93% after 6000 charge and discharge cycles). These boosted results are ascribed to the formation of multistage honeycomb-walled MPO/CP nanosheets with optimized crossover and multivalency, which promotes MPO/CP with faster transport channels and more reactive sites. Moreover, the P element can reasonably modulate the electronic structure, reduce the internal resistance of ion or electron transport, as well as give full play to the synergistic effect, which can enhance the electrochemical function. Meanwhile, the constructed MPO/CP//AC asymmetric supercapacitor achieves an energy density of 34.3 Wh kg−1 at a power density of 707.2 W kg−1. An encouraging stability of 86.2% was obtained after 8000 cycles at 10 A g−1. Thereby, the proposed novel MPO/CP electrode material with modified electrochemical properties was developed as a prospective candidate for application in energy storage devices.

Biomass derived N/O self-doped porous carbon for advanced supercapacitor electrodes

To satisfy the practical needs of the sustainability and industrialization of supercapacitors, it is essential to maintain good electrochemical performance at high mass loading above the commercial levels (10 mg cm−2). Herein, a unique 3D porous carbon with high mass loading is successfully prepared from Linum usitatissimum L. stem via a simple route of high temperature carbonization and subsequent KOH activation. The as-prepared porous carbon displays rich N/O heteroatoms, hierarchical porous, and interconnected vertical channels, which enable fast electron/ion transport and afford additional capacitance. These characteristics give the resultant carbon high capacitances of 434/245 F g−1 at 1/50 A g−1. Importantly, the as-prepared carbon can achieve mass loadings of 20 mg cm−2 and maintain decent electrochemical performance at this mass loadings, owing to short electron/ion transfer pathway as well as sufficient active sites. Specifically, the assembled symmetric supercapacitor delivers superior areal capacitance of 3.7 F cm−1 at 1 A g−1 and remarkably capacitance retention of 2.5 F cm−1 at 5 A g−1 under 20 mg cm−1. This work enlightens a sustainable and facile way for constructure advanced electrode material.

Polynaphthalene-Based Oxazaborinine Complexes Formulated as Red Light Emitters and High-Performance Asymmetric Supercapacitors.

Developing a solid organic emitter based on an oxazaborinine complex with improved photophysical characteristics has become essential to fulfilling the rising need for optical and electrochemical technology. Two oxazaborinine complexes (TNB (a tri-naphthalene boron complex) and DNB (a di-naphthalene boron complex)) decorated with naphthalene and triphenylamine have been developed, which show emission in the red light region in the solid phase. Their effectiveness as asymmetric supercapacitor electrodes in aqueous electrolytes is also being studied. Polynapthaldimine-substituted DNI (di-naphthalene imine) and TNI (tri-naphthalene imine) have been initially synthesized and converted to a N,O-linked boron complex. TNB in solids (λem 660 nm) and the polydimethylsiloxane (PDMS) composite (λem 632 nm) emit pure red light. The optimized structure has been generated, and the HOMO-LUMO energy was calculated with the help of density functional theory (DFT). Due to the higher conjugation effect and lower HOMO-LUMO energy difference, TNB could be used as a supercapacitor electrode. In a three-electrode configuration, TNB has a maximum specific capacitance of 896.25 F/g. Furthermore, an asymmetric supercapacitor device (ASC) was fabricated in an aqueous electrolyte using TNB as a positive electrode having a high specific capacitance of 155 F/g. Even in an aqueous electrolyte, the ASC device reached the operating potential window of 0 to 1.4 V with an enhanced energy density of 42.19 W h/kg and ∼96% cyclic stability after 10 000 cycles. The reported oxazaborinine complex and its electrochemical efficiency in aqueous electrolytes make it ideal for supercapacitor applications and directly impact the development of advanced electrodes for next-generation supercapacitors.

High-valent bimetal Ni2P/Co2P heterostructures induced by Mo doping as an advanced electrode for hybrid supercapacitors

The development of advanced electrode materials with fast reaction kinetics and optimized morphology is key to achieving high-performance hybrid supercapacitors with high energy density and outstanding cycling performance. Herein, an ingenious strategy is developed to prepare M doped Ni2P/Co2P (M = Cu, Zn, Mo) bimetallic phosphide electrode materials with heterostructure. For the Mo-doped Ni2P/Co2P, the unique morphology of hollow nanocubes consisting of ultrathin nanosheets facilitates the availability of more electrochemical active sites and relieves the deformational effects. In addition, the formation of heterogeneous structures modulates the electronic structure and the causes redistribution of interfacial charges, while the introduction of Mo cation can promote the formation of more high-valent Ni/Co sites, which synergistically accelerate reaction kinetics. Consequently, the Mo-Ni2P/Co2P hollow nanocubes with heterogeneous interfaces exhibit an optimal specific capacitance of 2300 F g−1 at 1 A g−1. In addition, when combined with activated carbon (AC) as a hybrid supercapacitor (HSC), the Mo-Ni2P/Co2P //AC device displays an energy density of 35.56 Wh kg−1 at a splendid power density of 800.0 W kg−1 and a remarkable cycling performance (the capacitance retention of 84.83% after 15,000 cycles). This study reveals that the introduction of Mo cation induces the formation of high-valence Ni/Co, providing a meaningful reference for the construction of high-performance metal phosphides with unique morphology and massive phase boundaries.

Self-assembled hierarchical porous nanoarchitectured 2,6-diaminopyridine decorated N-doped reduced graphene oxide as advanced electrode for high-performance aqueous Zn-ion hybrid supercapacitors

2,6-diaminopyridine (DAP), an active organic molecule containing amino groups and pyridine N is expected to be an attractive material for energy storage due to its fast and reversible proton-involved redox activity. Herein, the novel N-doped (or CNTs) and DAP organic molecules double-modified reduced graphene oxide nanocomposites with hierarchical porous nanoarchitectures were successfully designed and synthesized by a simple solvothermal method. Benefiting from the advantages of the three components and the positive synergistic enhancement between them, the newly synthesized N-RGO/DAP and CNTs/RGO/DAP nanocomposites exhibit excellent electrochemical properties, such as high specific capacitance, excellent rate capability and cycling stability. Furthermore, the Zn-ion hybrid supercapacitor further assembled with the optimal N-RGO/DAP as cathode delivers excellent Zn-ion energy storage performance in aqueous electrolyte, with a high specific capacitance (capacity) of 320.2 F g−1 (158.3 mAh g−1), excellent energy density of 140.9 Wh kg−1 at a power density of 534 W kg−1, and an ultra-long durability of 95.3% capacitance retention after 16,000 cycles at a large current of 100 mV s−1. This paper provides a novel strategy and advanced electrode nanocomposite with excellent electrochemical properties, which shows great promise in high-performance energy storage devices with high-flexibility, light-weight and sustainability.

Comparative research of hierarchical CoS2@C and Co3S4@C nanosheet as advanced supercapacitor electrodes

Transition metal sulfides (TMSs) are regarded as promising candidates for supercapacitors owing to their low cost, excellent redox reversibility, and electronic conductivity. However, slow ion diffusion and sharp volume expansion during electrochemistry hinder the application. Herein, the 2D leaf-like ZIF-67 (ZIF-67-L) is used as the precursor for amelioratinge the calcination and then sulfuration process, and the novelly hierarchical structures of CoS2 and Co3S4 nanoparticles anchored on the carbon skeleton (CoS2@C and Co3S4@C) are constructed. Compared with the inhomogeneous distribution of nanoparticles of Co3S4@C, the larger specific surface area is provided by numerous CoS2@C nanoparticles embedded in the 2D carbon skeleton and connected into sheets through effectively morphological construction, which provides more redox channels and active sites for electrochemical reactions. The CoS2@C electrode presents a superior electrochemical property with a high specific capacitance of 1151 F g−1 at 1.0 A g−1, which is 1.69 times larger than those of Co3S4@C. Density functional theory (DFT) calculations illustrate that CoS2 can transfer much more charge and have higher electronic activity in the process of OH− adsorption as compared with Co3S4, which proves that CoS2 has better conductivity. Moreover, an asymmetric supercapacitor constructed with the CoS2@C//reduced graphene oxide (RGO) displays a high energy density of 46.52 Wh kg−1 at a power density of 800 W kg−1. This work provides theoretical and methodological guidance for the rational composition control and distinct morphological preparation of transition metal sulfides.

Recyclable Fe3O4/MWCNT/CNF composite nanopaper as an advanced negative electrode for flexible asymmetric supercapacitors

This work constructed recyclable Fe3O4/MWCNT/CNF composite nanopaper, exhibiting exceptional flexibility, high electrical conductivity, and extraordinary mass- and area-specific capacitances as the negative electrode.

Few-layered Ti3C2TXcoupled with Fe3O4nanoparticles assembled in a reduced graphene oxide hydrogel as advanced electrodes for high-energy supercapacitors

A high-performance symmetric supercapacitor device based on free-standing 3D porous Fe3O4@Ti3C2TX–rGO heterostructure hydrogel electrodes is built.

Phosphorus doped molybdenum disulfide regulated by sodium chloride for advanced supercapacitor electrodes.

As a pseudocapacitor electrode material, molybdenum disulfide (MoS2) usually shows inferior capacity, rate capability and cyclability. Structural regulation and heteroatom doping are the available methods to ameliorate the electrochemical properties of MoS2. Herein, phosphorus doped molybdenum disulfide regulated by sodium chloride (SP-MoS2) is successfully synthesized using phosphomolybdate acid as a molybdenum source and an in situ dopant and sodium chloride (NaCl) as a structural regulator. Under the structural regulation of NaCl, the SP-MoS2 nanosheets exhibit an interweaved architecture with a large interlayer spacing of 0.68 nm. Owing to the in situ P doping and large specific surface area (21.0 m2 g-1), the SP-MoS2 electrode possesses a maximum capacity of 564.8 F g-1 at 1 A g-1 and retains 56.3% of the original capacity at 20 A g-1. Density functional theory (DFT) calculations indicate that SP-MoS2 displays a high K+ average adsorption energy of -3.636 eV. In addition, the fabricated SP-MoS2//AC asymmetric supercapacitor device displays an energy density of 22.8 W h kg-1 at 759 W kg-1.

A strategy of making waste profitable: Self-templated synthesis of helical rod structured porous carbon derived from Ganoderma Lucidem for advanced supercapacitor electrode

A strategy of making waste profitable: Self-templated synthesis of helical rod structured porous carbon derived from Ganoderma Lucidem for advanced supercapacitor electrode

One-pot synthesis of flower-like Ni-Co/reduced graphene oxide layered double hydroxide nanocomposites as advanced electrodes for high-performance asymmetric supercapacitors

Novel electrode materials with appropriate architectures are always desired to increase the energy density of supercapacitors. Here, the design and fabrication of NiCo-layered double hydroxides (NC-LDH) in composition with reduced graphene oxide (rGO) were prepared as high-performance electrodes for supercapacitors. In particular, a facile and one-pot scheme was designed for the growth of NC/rGO-LDH composites, which exhibited a high specific surface area of 204 m2/g. The compositional features of the composites, i.e., a two-dimensional flower-like layered architecture and conductive rGO, contributed to their highly impressive specific capacitance (1913.5 F/g at 1 A/g) and excellent cyclic performance. Furthermore, an asymmetric supercapacitor was designed using NC/rGO-LDH composites as the positive electrode and activated carbon as the negative electrode, which displayed a high energy density of 59.2 Wh/kg at a power density of 750 W/kg.

Retraction Note: Fabrication of hexagonal shaped CuCo2S4 nanodiscs/graphene composites as advanced electrodes for asymmetric supercapacitors and dye sensitized solar cells (DSSCs)

Retraction Note: Fabrication of hexagonal shaped CuCo2S4 nanodiscs/graphene composites as advanced electrodes for asymmetric supercapacitors and dye sensitized solar cells (DSSCs)

Impact of hybridization on specific capacitance in hybrid NiO/V2O5@graphene composites as advanced supercapacitor electrode materials

Currently, hybrid composites are considered promising materials in energy applications. Among various approaches for synthesizing hybrid composites, the solution combustion approach has attracted significant research interest worldwide due to its high versatility, efficiency, simplicity, scalability, reproducibility, and cost-effectiveness. Further, solution combustion synthetic techniques have recently been regarded as one of the more facile methods for developing effective supercapacitor electrodes. This paper provides the synthesis of vanadium pentoxide (V2O5), nickel oxide-vanadium pentoxide (NiO/ V2O5), and nickel oxide-vanadium pentoxide-Graphene (NiO/ V2O5@Graphene) nano-composites using solution combustion method. The importance of the hybridization of transition metal oxide with other-transition metal oxide and carbon derivatives is studied systematically. The obtained materials are characterized by X-ray diffraction, UV-Visible spectroscopy, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, Energy-dispersive X-ray analysis, Cyclic voltammetric analysis, Galvanostatic charge-discharge, and Electrochemical impedance. The average crystalline sizes are calculated as 27 nm, 24 nm, and 14 nm for V2O5, NiO/ V2O5, and NiO/ V2O5@Graphene nano-composites. The UV-Visible, Fourier transform infrared, and Energy-dispersive X-ray spectroscopy analysis confirms the formation of synthesized materials. Field emission scanning electron microscopy provides the distribution of NiO/ V2O5 nano-composite over the graphene sheet. The electrochemical performance of V2O5 is improved drastically with the simultaneous hybridization of two metal oxides. Further, the addition of graphene makes a small enhancement in the specific capacitance of the nano-composites. The order of specific capacitance is V2O5 (328 F/g) ˂ NiO/V2O5 (918 F/g) ˂ NiO/V2O5@Graphene (939 F/g). The solution resistance and charge transfer resistance of the modified electrodes are in the order of V2O5 (1.59 Ω) ˃ NiO/V2O5 (0.85 Ω) ˃ NiO/V2O5@Graphene (0.73 Ω) and V2O5 (5.66 Ω) ˃ NiO/V2O5 (1.35 Ω) ˃ NiO/V2O5@Graphene (0.17 Ω) respectively, which supports the enhancement in specific capacitance upon hybridization. The obtained materials are cost-effective, low-toxic, and efficient, hence would be appropriate for industrial use.

Biomass derived carbonaceous materials with tailored superstructures designed for advanced supercapacitor electrodes

Supercapacitors (SC), as one of the most competitive energy storage devices, are receiving great attention in R&D community. Carbonaceous materials for supercapacitor electrodes with high performance possess many attractive advantages, such as large specific surface area (SSA), hierarchical porous superstructures and excellent conductivity. Herein, biomass based materials are often utilized as versatile precursors for activated carbon production due to their inherent merits, including low cost, abundance, renewability, high carbon content, environmental friendliness, genetically unique nature structure. As known, the capacitance performance of biomass based carbon-assembled supercapacitors is mainly directly proportional to the exceptional skeleton robustness, high SSA and electroactive site content within carbonaceous framework. In this review, special attentions will be paid to the latest research progress of carbonaceous materials derived from biomass with tailored hierarchical superstructures to highlight their impact on the electrochemical performance of assembled supercapacitor. The objective of this paper is to present a critical review on the most recent publication related to biomass oriented carbonaceous electrodes for outstanding supercapacitor electrodes. Furthermore, the perspective for the progress and development of biomass based carbonaceous electrodes for high performance supercapacitors will also be provided, to underscore the current critical issues and future opportunities. • Carbon derived from biomass with tailored structure for supercapacitors was reviewed. • Methods for activating carbon with improved capacitance were reviewed and discussed. • Biomass based carbon and their key parameters/ characterizations were summarized. • The reasons why biomass derived carbon are suitable for electrodes were demonstrated. • Preparation methods and applications of biomass derived carbon were summarized and prospected.

Flexible Carbon Dots‐Intercalated MXene Film Electrode with Outstanding Volumetric Performance for Supercapacitors

Abstract2D MXenes have emerged as promising supercapacitor electrode materials due to their metallic conductivity, pseudo‐capacitive mechanism, and high density. However, layer‐restacking is a bottleneck that restrains their ionic kinetics and active site exposure. Herein, a carbon dots‐intercalated strategy is proposed to fabricate flexible MXene film electrodes with both large ion‐accessible active surfaces and high density through gelation of calcium alginate (CA) within the MXene nanosheets followed by carbonization. The formation of CA hydrogel within the MXene nanosheets accompanied by evaporative drying endow the MXene/CA film with high density. In the carbonization process, the CA‐derived carbon dots can intercalate into the MXene nanosheets, increasing the interlayer spacing and promoting the electrolytic diffusion inside the MXene film. Consequently, the carbon dots‐intercalated MXene films exhibit high volumetric capacitance (1244.6 F cm−3 at 1 A g−1), superior rate capability (662.5 F cm−3 at 1000 A g−1), and excellent cycling stability (93.5% capacitance retention after 30 000 cycles) in 3 m H2SO4. Additionally, an all‐solid‐state symmetric supercapacitor based on the carbon dots‐intercalated MXene film achieves a high volumetric energy density of 27.2 Wh L−1. This study provides a simple yet efficient strategy to construct high‐volumetric performance MXene film electrodes for advanced supercapacitors.