Excellent Supercapacitive Performance Research Articles

Facile and low‐cost production of Lantana camara stalk‐derived porous carbon nanostructures with excellent supercapacitance and adsorption performance

Facile and <scp>low‐cost</scp> production of <scp> <i>Lantana camara</i> stalk‐derived </scp> porous carbon nanostructures with excellent supercapacitance and adsorption performance

Construction of Ta-Cu7S4 negative electrode for high-performance all-solid-state asymmetric supercapacitor

Constructing electronic structure of the electrode materials is an effective approach to enhance the electrochemical activity. The substitution of high-valence metal ions can optimize the electronic structure of host materials. And there are few reports using this way to enhance supercapacitor performances. Herein, the isomorphous replacement by tantalum in Cu7S4 (Ta-Cu7S4) materials were fabricated by hard-template method and designed as negative electrode materials for solid-state supercapacitor (SSC). The unique hollow structure increased the specific areas of active materials and enabled the effective contact between electrode and electrolyte. Density functional theory (DFT) calculations indicate that the replacement of Ta element optimized the electronic structure, endowing the Ta-Cu7S4 with good electrical conductivity and more active sites. Moreover, the Ta element acted as an ‘electron reservoir’, which decreased the adsorption energy of OH– on the surface of electrode material, carried the electron to trigger redox reaction on Cu active sites continuously. These factors resulted the obtained Ta-Cu7S4 exhibited the excellent supercapacitor performances. When used as a negative electrode material, the Ta-Cu7S4 had an outstanding specific capacitance (675F g−1 at 1 A g−1) and good rate capacity (363.1F g−1 at 10 A g−1). In addition, the assembled SSC showed high energy density (111.1 Wh kg−1 at power density of 800 W kg−1) and long-term cyclic stability of retaining 83.3% after 5000 charge/discharge cycles. This work reports a low-cost and efficient Cu7S4-based supercapacitor material by Ta incorporating, and infer this new strategy can be used in other energy storage application devices.

Template induced self-oxidative polymerization of phenols to mesoporous carbon doped with faradaic active oxygen for high-performance supercapacitor

Facile synthesis of nanocarbons with rich faradaic-active functionalities is urgently needed for supercapacitor in aqueous electrolytes to address the bottleneck of low energy density (usually below 10 Wh/kg). Herein, we report a template induced self-oxidative polymerization method for the fabrication of nanocarbon with commercial Mg(OH)2 as template to absorb phenol (catechol or phloroglucinol) via acid-base interaction. The absorbed phenol undergoes self-oxidative polymerization to form a composite of polyphenol and template. The resultant flower-like material with open access morphology display large surface area (1303 m2/g), rich mesoporosity (over 80%), and rich faradaic oxygen functionalities (7.4 atom%) in the forms of -C=O and -C–O- groups. Benefiting from these features, the phloroglucinol derived product (PMC973) exhibits excellent supercapacitor performances in aqueous electrolyte including ultrahigh energy density of 36.7 Wh/kg (at 1000 W/kg), maintaining energy density of 22.9 Wh/kg at 18 800 W/kg, superior capacitance retention of over 70% and excellent cycling stability with 97.8% capacity retention after 10 000 charge/discharge cycles, offering huge potential for energy storage. The developed strategy avoids the use of harmful formaldehyde as linker reagent, thus providing a green and simple approach for the fabrication of functional nanocarbons that are applicable in a large numbers of fields.

Constructing Fe3O4/Nitrogen-doped Graphene Composites with Rich Pyrrolic Nitrogen for Excellent Supercapacitor Performance

Constructing Fe3O4/Nitrogen-doped Graphene Composites with Rich Pyrrolic Nitrogen for Excellent Supercapacitor Performance

Chemical synthesis of nano-grained ytterbium sulfide thin films for supercapacitor application

Nano-grained ytterbium sulfide (Yb2S3) thin film is deposited by an inexpensive chemical bath deposition (CBD) method with excellent supercapacitive performance. The formation of Yb2S3 thin film is confirmed from XRD, FT-Raman, and XPS studies. The nano-grains like surface morphology of Yb2S3 thin film is observed using scanning electron microscopy and transmission electron microscopy techniques. The Yb2S3 film shows hydrophilic nature with a contact angle value of 61.2°. The electrochemical supercapacitive properties of Yb2S3 thin film are studied using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The Yb2S3 thin film exhibits a specific capacitance of 184.6 F g−1 in 1 M KOH electrolyte at a 5 mV s−1 scan rate. The symmetric solid-state supercapacitor device of configuration Yb2S3/KOH-PVA/Yb2S3 shows a specific capacitance of 15 F g−1 and energy density of 13.80 W kg−1 at power density 0.55 kW kg−1. The device exhibits 78% capacitive retention over 3000 cycles.

One-step development of octahedron-like CuCo2O4@Carbon fibers for high-performance supercapacitors electrodes

Abstract In this study, a facile one-step calcination-free approach is introduced to synthesize the copper-cobalt oxide octahedron-like structure (CCOOS). The as-prepared CCOOS on carbon fiber electrode exhibited a high specific capacitance of 1737 F g−1 (694.4 C g−1, 192.9 mAh g−1) at 1 A g−1 and outstanding cycling stability. The excellent supercapacitor performance is ascribed to the electroactive surface of Cu and Co oxide and the fast electron and ion transport in the mesoporous structure. The electrode exhibited a high energy density of 45 Wh kg−1 and a high power density of 7727 W kg−1. The reaction involved green synthesis without further post-heat treatment. The successful synthesis was considered to be simple and cost-effective, which supports the viability of this composite as an alternative activated material for high-performance flexible supercapacitors.

Nanoporous Carbon Materials Derived from Washnut Seed with Enhanced Supercapacitance.

Nanoporous activated carbons-derived from agro-waste have been useful as suitable and scalable low-cost electrode materials in supercapacitors applications because of their better surface area and porosity compared to the commercial activated carbons. In this paper, the production of nanoporous carbons by zinc chloride activation of Washnut seed at different temperatures (400–1000 °C) and their electrochemical supercapacitance performances in aqueous electrolyte (1 M H2SO4) are reported. The prepared nanoporous carbon materials exhibit hierarchical micro- and meso-pore architectures. The surface area and porosity increase with the carbonization temperature and achieved the highest values at 800 °C. The surface area was found in the range of 922–1309 m2 g−1. Similarly, pore volume was found in the range of 0.577–0.789 cm3 g−1. The optimal sample obtained at 800 °C showed excellent electrochemical energy storage supercapacitance performance. Specific capacitance of the electrode was calculated 225.1 F g−1 at a low current density of 1 A g−1. An observed 69.6% capacitance retention at 20 A g−1 indicates a high-rate capability of the electrode materials. The cycling stability test up to 10,000 cycles revealed the outstanding stability of 98%. The fascinating surface textural properties with outstanding electrochemical performance reveal that Washnut seed would be a feasible agro-waste precursor to prepare nanoporous carbon materials as a low-cost and scalable supercapacitor electrode.

Nitrogen and fluorine co-doped graphene hydrogel for high-performance supercapacitors

In this work, the nitrogen and fluorine co-doped graphene hydrogel (NFGH) with three-dimensional (3D) porous structure was prepared through a simple one-step hydrothermal method using graphene oxide and ammonium fluoride. The interconnected 3D skeleton porous structure synthesized by the self-assembly of graphene can effectively inhibit the agglomeration of graphene, which will provide more diffusion paths for the electrolyte ions. Benefiting from the wettability of nitrogen functional groups, the nitrogen doping effectively reduces the hydrophobicity of electrode caused by the doping of fluorine. Due to the 3D porous structure of NFGH and the incorporation of nitrogen and fluorine, the NFGH exhibits excellent supercapacitive performance. The maximum specific capacitance of NFGH electrode is up to 366 F g−1 in the aqueous electrolyte, and 98% capacitance can be maintained even after 10,000 cycles. These excellent supercapacitive performances demonstrate that the NFGH has a great potential for application in high-performance supercapacitors.

Reduced CoNi2S4 nanosheets decorated by sulfur vacancies with enhanced electrochemical performance for asymmetric supercapacitors

Nowadays, it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe, efficient and simple method. And these characteristics are usually related to the vacancies and impurities in the electrode. To investigate the effect of the vacancies on the electrochemical properties of the supercapacitor cathode material, the uniform reduced CoNi2S4 (r-CoNi2S4) nanosheets with sulfur vacancies have been successfully prepared by a one-step hydrothermal method. And the formation of sulfur vacancies are characterized by Raman, X-ray photoelectron spectroscopy and other means. As the electrode for supercapacitor, the r-CoNi2S4 nanosheet electrode delivers a high capacity of 1918.9 F g−1 at a current density of 1 A g−1, superior rate capability (87.9% retention at a current density of 20 A g−1) and extraordinary cycling stability. Compared with the original CoNi2S4 nanosheet electrode (1226 F g−1 at current density of 1 A g−1), the r-CoNi2S4 nanosheet electrode shows a great improvement. The asymmetric supercapacitor based on the r-CoNi2S4 positive electrode and activated carbon negative electrode exhibits a high energy density of 30.3 W h kg−1 at a power density of 802.1 W kg−1, as well as excellent long-term cycling stability. The feasibility and great potential of the device in practical applications have been successfully proved by lightening the light emitting diodes of three different colors.

Excellent Cyclic Retention and Supercapacitive Performance of Electrochemically Active Nanocomposite Electrode

In this work, electrochemically active polydiphenylamine-silica reinforced graphene nanocomposite was prepared via an interfacial chemical oxidative polymerization method for energy storage application. The morphological views of synthesized nanocomposite were captured through scanning electron microscope (SEM). The supercapacitance behaviour of fabricated modified electrode was investigated by electrochemical analyses such as galvanostatic charge–discharge (GCD) and bode plot experiments. These results found that the chemically modified nanocomposite provides a high conductivity and also an afforded specific capacitance of ∼433 F/g with good cycling retention of 91% upto 500 cycles. Furthermore, the attained data will help in the profound study and further developments in energy storage device applications.

Facile fabrication and structure control of SiO2/carbon via in situ doping from liquefied bio-based sawdust for supercapacitor applications

Porous SiO2-Carbon composites with excellent electrochemical performance were fabricated from liquefied bio-based sawdust via a simple in situ doping approach. Morphologies and pore textures of the samples were controlled effectively by doping with SiO2 and optimizing carbonization temperature. The morphologies of SiO2-Carbon composites from carbonization between 700–900 °C changed from bump-like to coral-like, to a network-like structure, and the pore textures changed from a disordered to an ordered structure. Benefitting from specific morphologies and pore textures, the large specific surface areas (538-780 m2/g) of the SiO2-Carbon composites exhibited excellent electrochemical performance for supercapacitors. Remarkably, the reticular-like SiO2-Carbon composites with an ordered porous structure at carbonization 900 °C revealed a high specific capacitance (260 F/g), energy density (23.1 wh/kg) and power density (640 w/kg) at a current density of 1.6 A/g in 1 M KOH electrolyte, as well as a good rate performance and stability (with capacitance retention above 97 % after 5000 cycles). Especially, the capacitance is around 1.4 times and 1.3 times higher than that of the undoped carbon and SiO2-Carbon carbonized at 700 °C, respectively. The results indicate that SiO2-Carbon composites should be a promising candidate for capacitive application, and the excellent capacitance is attributed to the contribution of pseudo-capacitance from the SiO2 doping and double layer capacitance from the special pore textures. This work provides a simple way for full utilization of biomass waste for supercapacitor material.

Cr-doped (Co, Ni)3S4/Co9S8/Ni3S2 nanowires/nanoparticles grown on Ni foam for hybrid supercapacitor

Abstract Utilizing a 4: 1 of Co/Cr molar ratio in the starting material, Cr-doped (Co, Ni)3S4/Co9S8/Ni3S2 nanowires/nanoparticles can grow on Ni foam (NF) hydrothermally. The sample shows excellent supercapacitive performance with a specific capacity of 310.3 mAh g−1 at 1 A g−1 (320.27 mAh cm−2 at 1 mA cm−2), which is superior to Ni3S2/NF, (Co, Ni)3S4/Ni3S2/NF and less Cr-doped (Co, Ni)3S4/Co9S8/Ni3S2/NF. Density functional theory (DFT) calculations disclose that the incorporation of Cr into Ni3S2 or spinel-type Ni3S4 can improve the electron conductivity, promote the electron transfer from Ni/S to Cr, and boost the adsorption of –OH, which is evidenced from XPS spectra. It promotes the electrochemical reaction between active sites and OH− in solution, resulting in enhanced supercapacitive property. Furthermore, it is expected that the doped Cr substitutes the B position of spinel-type AB2S4 (such as NiIINiIII2S4). The Cr-doped (Co, Ni)3S4/Co9S8/Ni3S2/NF//activated carbon asymmetrical supercapacitor (ASC) shows a maximum energy density of 53.24 Wh kg−1 at power density of 543.26 W kg−1, which is superior to previously reported ASC devices.

SnS2-gC3N4/rGO Composite Paper as an Electrode for High-Performance Flexible Symmetric Supercapacitors

The flexible, free-standing, durable SnS2-gC3N4/rGO paper material was prepared by vacuum filtration of the composite dispersion containing GO and the SnS2-gC3N4 composite structure which is synthesized by a simple hydrothermal method. The as-prepared SnS2-gC3N4/GO composite paper was converted to SnS2-gC3N4/rGO paper material by applying a chemical reduction process. SnS2-gC3N4/rGO paper material was characterized by using FESEM, XRD, Raman, XPS, and EIS spectroscopy techniques. The SnS2-gC3N4 composite, a porous flower-like structure, uniformly intercalated between the graphene nanosheets exhibited excellent mechanical stability, greatly improved active surface areas, and enhanced surface porosity, in comparison with the pristine rGO paper. SnS2-gC3N4/rGO composite paper material show a highest specific capacitance of 532 F g-1 at 1 A g-1 and good cycling stability with capacitance retention of 60 % at 4 A g-1 after 5000 cycles. Moreover, SnS2-gC3N4/rGO composite paper demonstrate an excellent supercapacitor performance compared to the gC3N4/rGO paper and pristine rGO paper. The flexible symmetric supercapacitor based on SnS2-gC3N4/rGO composite electrode exhibits remarkable mechanical flexibility, high capacitive performance (403 F g-1 at 1 A g-1) and high cycle stability (63.8% at 4 A g-1 after 1500 cycles). As a result, SnS2-gC3N4/rGO composite paper material is expected to be a promising material for high-performance energy storage applications.

High Surface Area Nanoporous Graphitic Carbon Materials Derived from Lapsi Seed with Enhanced Supercapacitance.

Nanoporous activated carbon materials derived from agro-wastes could be suitable low-cost electrode materials for high-rate performance electrochemical supercapacitors. Here we report high surface area nanoporous carbon materials derived from Lapsi seed agro-waste prepared by zinc chloride (ZnCl2) activation at 700 °C. Powder X-ray diffraction (pXRD) and Raman scattering confirmed the amorphous structure of the resulting carboniferous materials, which also incorporate oxygen-containing functional groups as confirmed by Fourier transform infrared (FTIR) spectroscopy. Scanning and transmission electron microscopy (SEM and TEM) analyses revealed the granular, nanoporous structures of the materials. High-resolution TEM (HR-TEM) confirmed a graphitic carbon structure containing interconnected mesopores. Surface areas and pore volumes of the materials were found, respectively, in the ranges from 931 to 2272 m2 g−1 and 0.998 to 2.845 cm3 g−1, and are thus superior to commercially available activated carbons. High surface areas, large pore volumes and interconnected mesopore structures of these Lapsi seed-derived nanoporous carbon materials lead to their excellent electrochemical supercapacitance performance in aqueous electrolyte (1 M H2SO4) with a maximum specific capacitance of 284 F g−1 at a current density of 1 A g−1. Furthermore, the electrodes showed high-rate capability sustaining 67.7% capacity retention even at high current density of 20 A g−1 with excellent cycle stability achieving 99% capacitance retention even after 10,000 charge–discharge cycles demonstrating the potential of Lapsi seed derived nanoporous carbons as suitable electrode materials in high-performance supercapacitor devices.

Fishbone-derived N-doped hierarchical porous carbon as an electrode material for supercapacitor

A cost-effective and sustainable approach has been developed to synthesize N-doped carbon material from fishbone waste via a one-step carbonization without an addition of chemical activator as a catalyst. The carbonization temperature can be optimized so that a favorable layered structure is achieved in 3D-flake nitrogen-doped hierarchical porous carbon (NPC). NPC-850 (NPC that was carbonized at 850 °C) not only has a high specific surface area of up to 1337 m2 g−1, but is also richly doped with heteroatoms (N and O content of 5.8 and 7.99 at.%, respectively). NPC-850 also exhibits an excellent electrochemical supercapacitor (SC) performance, i.e., a maximum specific capacitance of 476 F g−1 in a three-electrode system and 354 F g−1 in a symmetrical SC (both in a 1 M H2SO4), and a maximum energy density of 21.2 Wh kg−1 in a symmetrical SC (in a 1 M TEABF4/AN). Moreover, NPC-850 can achieve high cycling stability, with 90.9% retaining of the original capacitance after 10,000 continuous cycles at a 1 A g−1 current density. Such an outstanding performance suggests that our facile and scalable synthesis technique is effective to prepare porous carbon from biomass for electrochemical energy storage.

A new lamellar larch-based carbon material: Fabrication, electrochemical characterization and supercapacitor applications

Efficient utilization of waste wood sawdust to prepare carbon-based materials with regular morphologies and pore structures continues to be of interest, with the ultimate aim of fabricating optimized electrode materials for use in energy storage devices. This work used a process involving the liquefaction of larch wood sawdust together with in situ doping of tetraethoxysilane (TEOS) to act as a silica-based template. This allowed the fabrication of carbon materials with a uniform lamellar structure. As a result of its specific morphology and its hierarchical pore structure, this larch-based carbon demonstrated excellent electrochemical supercapacitor performance. The regular lamellar structure provided transmission channels for ions and also promoted charge storage. Remarkably, the material showed high values of specific capacitance (288 F/g), energy density (93.73 Wh/kg) and power density (850 W/kg) at a current density of 0.2 A/g in a 1 M KOH electrolyte. Good rate performance and stability (with capacitance retention exceeding 97 % after 3000 cycles) were also observed. This work demonstrates a new approach to value-added utilization of larch waste by producing a material that is an excellent candidate for manufacture of supercapacitor electrodes.

Full-faradaic-active nitrogen species doping enables high-energy-density carbon-based supercapacitor

Abstract Nitrogen doping is usually adopted in carbon based supercapacitor to enhance its relatively low energy density by providing extra pseudocapacity. However, the improvement of energy density is normally limited because the content of the introduced nitrogen species is not high and meanwhile only part of them is electrochemically active. Herein, we designed and fabricated a class of hierarchical nitrogen-rich porous carbons (HNPCs) possessing not only very high nitrogen content (up to 21.7 atom%) but also fully electrochemically active nitrogen species (i.e., pyridinic N, pyrrolic N and oxidized N). Especially, in the synthesis of HNPCs, graphitic carbon nitride (g-C3N4) was used in situ not only as a nitrogen source but also as a catalyst to facilitate the polymerization of phenol and formaldehyde (as carbon precursor) and as a template to create the hierarchical porous structure. As electrodes for aqueous symmetric supercapacitor, the HNPCs with full faradaic-active nitrogen functionalities exhibit excellent supercapacitor performance: high energy density of 36.8 Wh/kg at 2.0 kW/kg (maintaining 25.7 Wh/kg at 38 kW/kg), superior rate capability with 78% capacitance retention from 1.0 to 20 A/g and excellent cycling stability with over 95% capacitance retention after 10 000 cycles, indicating their promising application potential in electrochemical energy storage. This novel carbon material with high-content and full electrochemically active nitrogen species may find extensive potential applications in the energy storage/conversion, catalysis, adsorption, and so on.

Controllable synthesis of gossamer-like Nb2O5-RGO nanocomposite and its application to supercapacitor

The gossamer-like Nb2O5-RGO nanocomposite was synthesized through a solvothermal treatment, and the Nb2O5 nanoparticles were uniformly coated on the RGO sheets. The size of the Nb2O5 nanoparticles is about 200–700 nm. The applications of Nb2O5-RGO as supercapacitor were then explored systematically. The morphology, textural structure, and physicochemical property of Nb2O5-RGO were investigated by using SEM, TEM, XRD, FT-IR, TG, and Raman. The electrochemical performance of RGO, Nb2O5, and Nb2O5-RGO was assessed through CV and galvanostatic charge-discharge test. The experimental results show that gossamer-like Nb2O5-RGO exhibits partial faradic pseudocapacitance and good electrical double layer capacitance property. The specific capacitance value 299.23 Fg−1 of Nb2O5-RGO nanocomposite is about 2.7 and 1.7 times higher than that of Nb2O5 and RGO, retaining 87.72% of its initial capacitance after 2000 cycles under the optimized conditions, which demonstrate that more ordered binary architecture Nb2O5-RGO nanocomposite along with easy synthesis possesses faster charge-discharge kinetics and excellent supercapacitive performance.

Facile synthesis and characterization of Co3O4 nanoparticles for high-performance supercapacitors using Camellia sinensis

In this study, synthesis and characterization of cobalt oxide nanoparticles (Co3O4 NPs) using green tea leaf (Camellia sinensis) and its utilization as high-performance supercapacitors has been studied. Co3O4 NPs were fabricated utilizing aquatic extract of Camellia sinensis as a reduction agent, and it was annealed at various annealing temperatures, such as 200 °C, 400 °C, 600 °C, and 800 °C for 2 h. The synthesized Co3O4 NPs were analyzed using XRD, FESEM, EDX, HRTEM, PL, FTIR, UV–visible techniques. The higher concentration of phenolic compounds with antioxidant potential, amino acids, proteins and lipids in Camellia sinensis act as the reducing as well as the stabilizing agents for the growth of NPs. The XRD analysis confirms that the crystalline behavior of the annealed samples increases with increasing annealing temperature. The electrochemical performance of green synthesized nanostructured Co3O4 NPs shows an excellent supercapacitance performance with quick dispersing of electrolyte ions into the Co3O4 electrode owing to their rapid charging and discharging performances. This affirms that the bio-synthesized Co3O4 nanomaterial is the appropriate material for high performance supercapacitor applications.

Hydrangea-like N/O codoped porous carbons for high-energy supercapacitors

Carbons with specific morphologies, compositions and structures have aroused scientific and technological interest due to their intriguing and overwhelming properties for multi-purpose applications. Herein, a novel route to convert Knoevenagel copolymer into hydrangea-like, N/O codoped, and high-surface-area porous carbon (HPC) spheres with excellent supercapacitive performances is presented. By crosslinking p-phenylenediacetonitrile with two aromatic aldehyde co-monomers, as-prepared material exhibits a unique architecture of intertwined nanosheets uniformly self-assembled on the surfaces of microporous spheres. Featuring a large adsorbing platform (1963 m2 g−1), multi-scale pore structure and diverse N/O functional groups, HPC electrode carbonized-activated at the optimal temperature of 700 °C yields a prominent capacitance of 330 F g−1 at 1 A g−1, along with a satisfactory rate capability of 221 F g−1 at 20 A g−1 in KOH electrolyte. More importantly, taking advantage of a refined interphase between the high-concentration water-in-salt Li-TFSI layer and the ion-accessible hydrangea surface, HPC-based supercapacitor gives a higher energy delivery of 32.9 Wh kg−1 at 575 W kg−1 than the common devices using KOH (10.93 Wh kg−1 at 100 W kg−1) and Na2SO4 (24.9 Wh kg−1 at 180 W kg−1), with high-voltage aqueous durability of 90.5% retention over 10,000 cycles at 2.3 V. This inspiring work enriches the methodology for fabricating functionalized carbon spheres that are expected to boom diverse applications.