Supercapacitive Properties Research Articles

Metal oxide-mixed polymer-based hybrid electrochromic supercapacitor: improved efficiency and dual band switching

The inclusion of charge storage properties in electrochromic devices (ECDs) has gained much interest and has evolved into a promising emerging energy-related field due to multifunctional smart device applications. Here, an organic–inorganic solid-state asymmetric electrochromic supercapacitor device (ESCD) containing nano-CoTiO3-mixed poly-3-hexylthiophene and WO3 as two electrodes has been designed to study electrochromic and supercapacitor properties. The electrochemical properties of CoTiO3 show a pseudocapacitive-type charge storage capability, which has been utilized to enhance the electrochromic performance of the ESCD with additional charge storage ability. The device shows charge storage properties with fast charging and slow discharging, giving very high coulombic efficiency with a specific capacitance of 6.4 mF cm−2 at 0.2 mA cm−2 current density. The device shows excellent electrochromic supercapacitive properties with a color contrast of ∼50% and a short switching time of ∼1 s at a 515 nm wavelength with excellent cyclic stability. The device exhibits the capability to cut near infrared wavelength (700 nm and 850 nm) and has a potential application as a heat filtering device. Thus, the addition of pseudocapacitive-type materials in ECDs enhances the capacitive performance along with electrochromic properties, which makes ECDs more suitable for real life applications.

One-pot synthesis of phosphorous, iodine atoms co-functionalized graphene for high-performance supercapacitor and flame-retardant applications

There has been extensive research on heteroatom-doped graphene for electrochemical energy storage and flame-retardant (FR) applications. Herein, we used a one-pot method for developing phosphorous, iodine co-doped reduced graphene oxide (PI@rGO) from red phosphorus and iodine via in situ graphene oxide (GO) reduction for supercapacitor and FR applications. In a symmetrical two-electrode cell device, the as-prepared PI@rGO demonstrated good super capacitive performance of 178 F g−1 at a current density of 1.0 A g−1, along with an exceptional energy density of 20 Wh kg−1 and power density of 1791 W kg−1. The as-synthesized PI@rGO demonstrated outstanding cyclic stability at a high current density of 10 A g−1, retaining up to 84 % of its initial capacitance after more than 6000 recurrent charge–discharge cycles. The synthesized PI@rGO showed excellent FR properties toward cotton fabric and sustained cotton fabric up to 337 s with continuous flame exposure. The control cotton fabric was completely burned in 16 s. The synthesized PI@rGO coated cotton fabric showed an excellent value of 39 % limiting oxygen index and residual char length of 2 cm. With the excellent super capacitive performance and FR properties, PI@rGO can be a promising candidate for different applications including supercapacitors and FR products.

Fabrication of magnesium indium oxide (MgIn2O4) based on rGO for supercapacitor application

In recent decades, researchers have gained interest in metal-based oxide with carbon for supercapacitive electrode material primarily due to their exceptional power density, larger active surface area, distinctive reversibility and cost-effectiveness. This study provides the novel fabrication of MgIn2O4 (MIO) and MgIn2O@rGO via hydrothermal technique regarding supercapacitor electrodes. The supercapacitive properties of MgIn2O4 (MIO) and MgIn2O@rGO nanostructures were assessed in an aqueous 2.0 M KOH electrolytic solution using various electrochemical analyses. The synthesized MIO@rGO nanostructures demonstrated a brilliant capacitance of 986.09 F g−1 at 10 mV s−1 obtained from CV analysis. Additionally, it demonstrates excellent capacitive performance when combined with rGO and MIO@rGO composite demonstrated the specific capacitance values of 1589.15, 784.93, 674.53 and 452.47 F g− 1 at the current density ranges from 1 to 4 A g− 1, respectively from GCD investigation and also it attained a maximal energy of 59.82 Wh kg−1 and power density of 260.31 W kg−1. Therefore, the newly created material can be utilized in future generations on energy-storing systems, supercapacitor electrodes and energy conversion technologies.

Pre‐Oxidating and Pre‐Carbonizing to Regulate the Composition and Structure of Coal Tar Pitch: The Fabrication of Porous Carbon for Supercapacitor Applications

AbstractThe capacitive properties of supercapacitors highly rely on the reasonable design of high‐performance electrode materials. Herein, a synergetic strategy of pre‐oxidation and pre‐carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre‐oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre‐carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre‐oxidation and pre‐carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g−1. Meanwhile, ZnCl2 is used as a hydrogen‐bonding acceptor to synthesize ZnCl2‐EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg−1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre‐oxidation and pre‐carbonization on the fabrication of CTP‐based carbon material and expects to prepare porous carbon using other pre‐oxidation/carbonization agents.

Synergistic effect of green trace K2CO3 and CO2 activation of zhundong coal for high-performance supercapacitors

Porous activated carbons prepared by green trace K2CO3-assisted CO2, H2O, and CO2/H2O activated high-alkali Zhundong coal are being employed as supercapacitor electrode materials. Effects of trace K2CO3 (2 wt% of carbon precursor) and gas composition on physicochemical structure, the morphology and supercapacitor properties of the active carbon are investigated in detail. The results are showing that activated carbon from trace K2CO3-assisted CO2 activation exhibited excellent performance, indicating that CO2 and K2CO3 have synergistic effect in the activation process. It is mainly due to the higher O content in CO2/N2 atmosphere and promotion by K of O transfer from CO2 to the carbon matrix, which produces more active sites. Trace K2CO3-assisted CO2 activated carbon forms a forked hierarchical pore structure, more oxygen-containing functional groups, increases surface free energy of porous carbon, more potassium-containing group structures, and excellent graphitization of amorphous carbon compared with the other carbons. Its corresponding electrode and symmetrical supercapacitor achieve specific capacitance of 277.7 and 114.5 F g−1, respectively. The energy density is 10.54 Wh kg−1 at 209.98 W kg−1 and the material retained 95.89% after 10 000 cycles. A novel method of green trace K2CO3-assisted CO2 activation of high-alkali Zhundong coal is proposed for high-performance supercapacitors.

The effect of B – site cation on the supercapacitive properties of LaBO3 (B = Cr, Mn, Fe and Co) porous perovskites

Perovskite oxides have attracted great attention as favorable electrode materials for supercapacitors due to their sole structure, intrinsic oxygen vacancy and compositional flexibility. However, a facile synthetic route which is simple and economical is a challenging issue related to the synthesis of such complex functional oxides. We present a facile and ultrafast way to synthesize LaBO3 (B = Cr, Mn, Fe and Co) perovskite nanocrystallites using glycine-nitrate autocombustion followed by annealing. The structure, phase purity, thermal stability, morphology and surface features of thus synthesized perovskite oxides were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmet-Teller measurements. The role of B – site cation on the electrochemical performance has been investigated by cyclic voltammetry, galvanostatic charge discharge measurements and electrochemical impedance spectroscopy. Electrochemical measurements showed that, among the synthesized materials, LaBO3 nanoparticles with smallest transition metal cation at its B – site, that is LaCoO3 delivered highest value of specific capacitance (750 F/g) and the value of specific capacitance decreases in the order LaCoO3 ˃ LaMnO3 ˃ LaCrO3 ˃ LaFeO3. Therefore, B – site transition metal cation holds the key to regulate perovskite's properties which are essential prerequisites for supercapacitors. An asymmetric device fabricated using LaCoO3 and activated carbon as the positive and negative electrode respectively acted in broad potential window (1.7 V) and delivered an energy density of 22.2 Wh/kg at a power density of 997.7 W/kg and two supercapacitors connected in series could power a red light emitting diode efficiently.

Transforming Disposed Face Masks into S‐Doped Carbon Nanofibers for High Performance Supercapacitors

AbstractThe substantial increase in discarded face masks since the onset of the COVID‐19 pandemic has resulted in extensive environmental pollution from plastic waste. This study presents a novel upcycling method to repurpose disposable face masks into a carbon‐based nanomaterial for use in supercapacitors. The upcycled sample, CSDFM@800, demonstrates very good supercapacitor properties, boasting a high specific capacitance of 234 F g−1 at a current density of 0.5 A g−1. Additionally, the symmetric coin cell supercapacitor constructed from this material exhibits excellent performance, achieving a high energy density of 8.54 Wh kg−1 at a low current density of 0.5 A g−1, and maintaining superior capacitance retention of 96.8 % after 15,000 charge/discharge cycles at a current density of 10 A g−1. Materials characterisation results and electrochemical analysis reveal that this upcycling process not only preserves the carbon nanofiber structure but also introduces highly reactive sulfur as a heteroatom doping element.

Porous α-Fe2O3 Hollow Rods/Reduced Graphene Oxide Composites Templated by MoO3 Nanobelts for High-Performance Supercapacitor Applications.

Porous α-Fe2O3 hollow rods/reduced graphene oxide (α-Fe2O3 HR/RGO) composites with unique morphological characteristics and a high surface area are prepared through a template strategy, which was systematically studied and found to have outstanding supercapacitive properties. When served as active material in a three-electrode setup, the optimized α-Fe2O3 HR/RGO-30, comprised 76.5 wt% α-Fe2O3 and 23.2 wt% RGO, was able to offer the largest specific capacitance of 426.3 F g-1, an excellent rate capability as well as satisfactory cycle life with capacitance retention of 87.7% and Coulombic efficiency of 98.9% after continuously charging/discharging at 10 A g-1 for beyond 10,000 cycles. Such electrochemical behaviors of the α-Fe2O3 HR/RGO-30 electrode can rival or even surpass those of many Fe2O3-based electrodes documented in the previous literature. Later, a symmetric supercapacitor cell of α-Fe2O3 HR/RGO-30//α-Fe2O3 HR/RGO-30 was fabricated. The assembled device offers the maximum energy density of 18.7 Wh kg-1, and also exhibits commendable rate capability, and features stable cycling durability (with capacitance retention of 83.2% together with a Coulombic efficiency of 99.3% after 10,000-cycle charge/discharge at 5 A g-1). These notable electrochemical performances enable the α-Fe2O3 HR/RGO-30 composite to be a high-potential material for advanced energy storage systems.

One-step synthesis and fabrication of ZrMo2O8 nanostructures as advanced electrode material for energy storage applications

Nanostructures of metal molybdates show great potential as high-performance electrode materials for the forthcoming development of energy storage devices. In present work, ZrMo2O8 nanostructure was constructed using a simple chemical procedure and followed by examination with the aid of several spectral and analytical tools. The supercapacitive properties of ZrMo2O8 electrode material were investigated using Cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD) and Electrochemical Impedance Spectroscopy measurements (EIS). The as-prepared ZrMo2O8 nanostructures as supercapacitor (SC) electrode material exhibited pseudocapacitive performance with notable value of 288C g−1 at 1 A/g, significant cycling stability and 92.5% capacity retention with the coulombic efficiency of 87.4% even after 5000 GCD cycles at 1 A/g. The morphological investigations indicated that the higher Specific capacity (Cs) was primarily caused by the significant increase in active sites as well as active surface area. The Bode phase angle plot of ZrMo2O8 exhibited a low frequency intercept, with emphasis at approximately −52° phase angle, indicating a superior redox signature. The results infered that ZrMo2O8 nanostructures are promising candidates for high performance energy storage applications.

MOF Derived CoFe2O4@Carbon Nanofibers for Supercapacitor Application

This study presents the synthesis and electrochemical evaluation of MOF-derived CoFe2O4 nanoparticles anchored on carbon nanofibers (CoFe2O4@CNFs) for supercapacitor applications. By integrating hydrothermal and electrospinning techniques, we successfully fabricated CoFe2O4@CNFs with enhanced supercapacitive properties. The electrochemical performance of CoFe2O4@CNFs was rigorously assessed, revealing a remarkable specific capacitance of 527 F/g at a current density of 1 A/g. Additionally, the electrode demonstrated a power density of 234.93 W/kg and an energy density of 16.58 Wh/kg. These results highlight the synergistic effect of combining MOF-derived bimetallic transition metal oxides with carbon nanofibers, underscoring their potential in advancing supercapacitor technology. The findings suggest that CoFe2O4@CNFs can serve as a promising candidate for high-performance energy storage applications, offering a viable pathway to enhance the efficiency and capacity of supercapacitors.

Ultrafast Ion Transfer of Metal-Organic Framework Interface for Highly Efficient Energy Storage.

Flexible supercapacitors are favorable for wearable electronics. However, their high-rate capability and mechanical properties are limited because of unsatisfactory ion transfer kinetics and interfacial modulus mismatch inside devices. Here, we develop a metal-organic framework interface with superior electrical and mechanical properties for supercapacitors. The interfacial mechanism facilitates ultrafast ion transfer with an energy barrier reduction of 43% compared with that of conventional transmembrane transport. It delivers high specific capacity at a wide rate range and exhibits ultrastability beyond 30000 charge-discharge cycles. Furthermore, meliorative modulus mismatch benefited from ultrathin interface design that improves mechanical properties of flexible supercapacitors. It delivers a stable energy supply under various mechanical conditions like bending and twisting status and displays ultrastable mechanical properties with performance retention of 95.5% after 10 000 bending cycles. The research paves the way for interfacial engineering for ultrastable electrochemical devices.

Design of bifunctional sandwich-like Co@Si/Ox-MXene nanocomposite to increase the supercapacitor properties and removal of pollutants from wastewater

Spent supercapacitor electrodes are considered waste after the end of the cycle. Designing a multifunctional material to increase the specific capacity of supercapacitors and eliminate environmental pollution is one of the existing challenges. In this study, Co3O4 was extracted from waste CMB by several tandem hydrothermal methods. Also, 3-Aminopropyl-triethoxysilane (APTES) was used to exfoliate and surface modification of Ti3C2Tx MXene nanosheets. Then, by assembling Co3O4 on the synthesized Ti3C2Tx nanosheet, a sandwich composite of Co@Si/Ox-Ti3C2Tx was formed through the formation of a complex with active surface functional groups on the oxalic acid modified MXene surface. Co3O4 can increase the number of redox reaction sites and fast charge transfer in the conducting channels of MXene by penetrating interlayers. The Co@Si/Ox-Ti3C2 composite electrode showed an increased specific capacity of 1821 Cg−1 at a current density of 1 Ag−1. The prepared hybrid supercapacitor (HSC) with Co@Si/Ox-Ti3C2 composite as the positive electrode and silanized active nanocarbon (Si69@AC) with bis(triethoxysilylpropyl)tetrasulfide as the negative electrode had a high energy density of 50 Wh kg−1 up to a power density of 8422 W kg−1 along with excellent cyclic life of 90.87% capacitance retention. After 15,000 cycles, XRD and XPS analyses confirmed 62% degradation of the positive electrode and conversion to TiO2 after 30 days in water. To graft the separated and agglomerated elements, they were added to the TEOS solution and subjected to the sol-gel process. High photocatalytic properties, 97% degradation of methylene blue (MB), changing the absorption region from UV to visible due to changing its band gap to 3.3 eV were among the characteristics of the new material. This work is a new approach for the construction of eco-friendly new HSCs.

Supercapacitor properties of N/S/O co-doped and hydrothermally sculpted porous carbon cloth in pH-universal aqueous electrolytes: Mechanism of performance enhancement

Carbon cloth (CC) was hydrothermally etched in a highly oxidizable solution to form a porous structure for supercapacitor electrodes on the surface of CC. The oxygen-rich groups on porous CC (OCC) were then partially replaced by N and S elements to produce N/S co-modified porous OCC (MOCC). This method uses a lower temperature than the KOH etching method while maintaining the flexibility and self-supporting properties of CC. The modified MOCC electrodes were investigated as symmetric supercapacitors (SSCs) and compared to conventional collectors such as copper and aluminum foils. The SSCs were tested for electrochemical performance in acidic, alkaline, and neutral electrolytes, enabling them suitable for a wider range of applications. In the acid electrolyte, the device has an area capacitance of up to 3132 mF cm−2 at 1 mA cm−2 and a capacitance retention of 91 % after 20,000 cycles at 20 mA cm−2, outperforming the alkaline and neutral electrolytes. The devices had a maximum volume energy density of 1.82 mWh cm−3 and a maximum volume power density of 11.42 mW cm−3 when the MOCC electrodes were assembled as symmetrically flexible SCs with an acidic colloidal electrolyte, in addition to passing essential flexibility tests, which proved possible for application in the booming field of flexible energy storage. DFT simulations were conducted on CC, OCC and MOCC, which showed that N/S co-doping enhances the conductivity of OCC and increases the number of active sites, resulting in higher capacitance. This study demonstrates that MOCC can be mass-produced for consistent, high-performance flexible energy storage devices.

Tailoring the multifunctional properties of hydrothermally synthesized reduced graphene oxide/tungsten oxide supported nanorods to enhance the electrochemical and water-splitting activities

Herein, we employ the synergistic effect and better conductivity of graphene oxide (GO) and reduced graphene oxide (rGO) to boost the energy storage capacity and electrical conductivity of tungsten oxide (WO3) nanomaterials. The structural analysis of the WO3 and its composites revealed the presence of a monoclinic phase with a periodic arrangement. However, the field emission scanning electron microscopy revealed the nanorod-shaped morphology for WO3 and the nonuniform interconnected nanorod nanosheet-like morphology for composites. The identification of functional groups and stretching–bending vibrations of W–O, CO WO, and C–C bonds are revealed by FT-IR and Raman spectroscopy. Additionally, the transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the morphological, structural, and electronic states of hybrid rGO/WO3 nanostructures. The supercapacitive properties and electrocatalytic activity of WO3, GO/WO3, and rGO/WO3–nickel foam (NF) electrodes were investigated using a 2 M KOH via an three-electrode system in the desired potential window. As a result, the rGO/WO3 electrode exhibited promising electrochemical performance with a large specific capacity, 135 mAh/g (972 F/g) with high energy (ED), and power density (PD) of 33 Wh/kg and 1100 W/kg at 5 mA/cm2, and excellent retention of 92 % after 5000 CV cycles. However, the hybrid device is fabricated using rGO/WO3//rGO-NF as electrodes and exhibited a high specific capacity (78 mAh/g and 177 F/g at 5 mV/s), decent cycling stability (85 % after 5000 cycles), and high ED/PD (33 Wh/kg /1166 W/kg) respectively. Moreover, the electrocatalytic activity of WO3, GO/WO3, and rGO/WO3 electrodes was studied using 2 M KOH respectively. The superior electrochemical activities such as overpotential, Tafel slope, and the good electrochemical surface area (ESCA) of 328 mV, 95.5 mV/dec, and 38.2 cm2 with good stability were observed for rGO/WO3 electrode. The proposed asymmetric design provides promising material for developing next-generation energy storage devices for various portable electronic systems and water-splitting activity.

Hierarchical NiCo-LDHs/metal sulfides (V3S4, CuS, Mo2S3) heterostructures with improved electrochemical properties for asymmetric supercapacitors: A comparative study

A good approach to meet the high-performance requirements of supercapacitors is to introduce heterostructure to the transition metal sulfide electrodes. In this work, the hierarchical nanoflower-like NiCo-LDHs/V3S4 (NCs/V3S4) heterostructure is synthesized by the two-step hydrothermal process. The rational structure not only creates the sufficient active sites but also provides abundant ion/charge diffusion channels, facilitating the electrochemical reaction kinetics of the electrodes. NCs/V3S4 heterostructure, which advantages of the special structure and synergistic effect, exhibits a good rate capability and an exceptional specific capacitance of 1823.8 F g−1 at 1 A g−1 and 964.3 F g−1 at 30 A g−1. In addition, the assembled NCs/V3S4//AC asymmetric supercapacitors (ASCs) exhibit an exceptional energy density of 63.60 Wh kg−1 at a power density of 799.93 W kg−1 and good cycling stability with 99.04% capacitance retention after 6000 cycles, indicating that the strategy can improve ASCs stability and energy density. For comparison, NiCo-LDHs/Mo2S3//AC (NCs/Mo2S3//AC) and NiCo-LDHs/CuS//AC (NCs/CuS//AC) ASCs are assembled and the electrochemical performances of the three NCs/metal sulfides//AC ASCs are systematically investigated and compared. In conclusion, the distinctive structural design can successfully manage the interface charge states, ensuring the structural integrity of electrode materials and resulting in superior electrochemical performance.

Insight of super-capacitive properties of flexible gel polymer electrolyte containing butyl imidazole ionic liquids with different anions based on PVDF-HFP

Insight of super-capacitive properties of flexible gel polymer electrolyte containing butyl imidazole ionic liquids with different anions based on PVDF-HFP

Experimental and computational analysis of the structure-activity relationship of ionic gel electrolytes based on bistrifluoromethanesulfonimide salts for supercapacitors

Ionic gel (IG) electrolytes are emerging as promising components for the development of next-generation supercapacitors (SCs), offering benefits in terms of safety, cost-effectiveness, and flexibility. The ionic conductivity, stability, and mechanical properties of the gel electrolyte are relevant factors to be considered and the key to improving the performance of the SC. However, the structure–activity relationship between the internal structure of IGs and their SC properties is not fully understood. In the current study, the intuitive and regular structure–activity relationship between the structure and properties of IGs was revealed via combining computational simulation and experiment. In terms of conductivity, the ionic liquid (IL) ([EMIM][TFSI]) in the IG has a high self-diffusion coefficient calculated by molecular dynamics simulation (MDS), which is conductive to transfer and then improves the conductivity. The radial distribution function of the MDS shows that the larger the g(r) between the particles in the polymer network, the stronger the interaction. For stability, IGs based on [EMIM][TFSI] and [EOMIM][TFSI] ILs have higher density functional theory calculated binding energy, which is reflected in the excellent thermal stability and excellent capacitor cycle stability. Based on the internal pore size distribution and stress-strain characterization of the gel network ([ME3MePy][TFSI] and [BMIM][TFSI] as additives), the highly crosslinked aggregate network significantly reduces the internal mesoporous distribution and plays a leading role in improving the mechanical properties of the network. By using this strategy, it will be possible to design the ideal structure of the IG and achieve excellent performance.

Mo-doped porous Co3O4 nanoflakes as an electrode with the enhanced capacitive contribution for asymmetric supercapacitor application

Cobalt oxide (Co3O4) electrode materials have tremendous properties for supercapacitors, such as being environmentally friendly, having a high surface area, being low cost, and having high theoretical specific capacitance (3560 Fg−1). However, its poor electronic conductivity restricts the performance of the practical application. Doping transition metal ions into the host materials is an effective method to improve conductivity and enhance storage capacity. In this research work, we studied Mo-doped Co3O4 nanostructure electrodes synthesized using the electrodeposition technique. The integrated material samples were characterized by XRD, SEM with EDAX, XPS, FTIR, Raman spectra, UV–visible, and BET for their structure, morphology, composition, optical, and surface area properties. The 2 mM Mo-doped Co3O4 electrode exhibits excellent electrochemical pseudocapacitive properties. The optimized Mo2-doped Co3O4 shows a maximum specific capacitance of 1674 Fg−1 at 10 mA cm−2 current density in 1 M KOH electrolyte solution. Finally, the asymmetrical hybrid supercapacitor device (AsHScD) Mo2-Co3O4//rGO) demonstrates the highest power density of 159.0 KWKg−1 and maximum energy density of 13.80 WhKg−1 with a long-term stability of 95 % up to 2000 cycles. The Mo2-Co3O4 electrode is a promising candidate material for a charge-storage hybrid supercapacitor in an aqueous 1 M KOH electrolyte.

C3N4 improved nickel-cobalt layered double hydroxide (NiCoLDH) supercapacitive property

A flower-like composite of NiCoLDH/C3N4 is prepared using a simple one-step hydrothermal method. The morphologies and structure information of samples are observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties are measured by an electrochemical workstation and Land. The effects of the C3N4 mass loading on the capacitance of NiCoLDH/C3N4 composite are studied. The results show that the NiCoLDH/C3N4 composite exhibits a flower-like morphology and presents an impressive specific capacitance of 2677 F g−1 at 1 A g−1 for the optimized sample with C3N4 mass loading of 5 mg, higher than that of the pristine NiCoLDH (1676 F g−1). In addition, the assembled NiCoLDH/C3N4//YP50 supercapacitor device could achieve a maximum energy density of 33 Wh kg−1 and show a good capacitance retention of 97 % after 9000 cycles.

Novel hierarchical core-shell NiCo2S4@NiWO4 nanowire arrays for high performance pseudocapacitor

In this paper, a novel NiCo2S4@NiWO4 honeycomb core-shell nanorod array significantly improved the electrochemical storage properties of supercapacitors. The characteristic architecture of the NiCo2S4@NiWO4 electrode showed a remarkable specific capacity of 1273.5 C g−1 at a current density of 1 A g−1. The asymmetric supercapacitor (ACS) had a high specific capacitance of 1502.4 C g−1 at a current density of 1 A g−1 as well as excellent cycling stability at a current density of 10 A g−1 (101.25 % cycling retention rate after 10,000 cycles), and an energy density of 334 Wh kg−1 with a power density of 2.38 kW kg−1. The research emphasized that a strong electronic coupling effect was observed at the interface of NiCo2S4 and NiWO4 and electron transfer from Ni-W-O to Ni-Co-S occurred around the interface, which further improved the electron transfer properties of electrode materials and hit the mark extends the life of the electrode and significantly improves the performance of energy storage systems.