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[Display omitted] • NiO/Peanut shell activated carbon (Ni/PSAC) using wet impregnation method. • Ni/PSAC electrode delivered a specific capacitance of 848F g−1 at 8 A g−1. • Asymmetric device reporting energy density of 39.14 Wh kg−1. • For waste-to-effective energy storage, it is an excellent strategy. The approach outlined in this study provides insights into developing sustainable and cost-effective energy storage solutions utilizing agricultural waste materials focusing on using peanut shells to make activated carbon with subsequent impregnation of NiO for supercapacitor electrodes. X-ray diffraction analysis showed the NiO-impregnated peanut shell-activated carbon (Ni/PSAC) nanocomposite material had a face-centered cubic structure. The electrochemical behavior of Ni/PSAC electrode and Ni/PSAC//AC device were comprehensively deliberated through cyclic voltammetry (CV), Galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The GCD data of Ni/PSAC//AC device uncovered a boosted specific capacitance of 154.63F g−1, accompanied by an energy density of 39.14 Wh kg−1 and a power density of 2700 W kg−1 at 2 A g−1 current density. These findings suggest the potential of mesoporous Ni/PSAC electrode as an efficient and hopped-up material for asymmetric supercapacitor. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-O-doped Alpinia galanga stem-based carbon nanofiber succesfully synthesis. • The hierarchical porous carbon exhibit high specific surface area of 1065.58 m2/g. • The porous carbon was performed in solid-free binder form. • In 2-electrode system, supercapacitor possessed specific capacitance of 226F g−1. In this study, activated carbon with hierarchical pores and a nanofiber structure doped with oxygen was prepared using a pure biomass-based sustainable strategy involving integrated chemical impregnation and pyrolysis. Alpinia galangal stem was chosen as it functions as fast conductive network with abundant electrochemical active sites for high-grade electrode materials. The optimal precursor exhibited self-doping of oxygen ranging from 6.15 to 15.69 % with 1065.58 m2/g, which contributed to the redox reaction of the electrode material. When tested in a 2-electrode system, the porous carbon nanofibers showed a high specific capacitance of 226F g−1 at 1 A g−1 in 1 M H 2 SO 4 electrolyte, producing an energy density of 9.3483 Wh kg−1 with a coulombic efficiency of 89.01 %. The results showed that oxygen-doped hierarchical porous carbon nanofibers produced from Alpinia galangal stem biomass and designed to be solid-free of binders are highly promising as high-quality electrode materials that can improve sustainable supercapacitor performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The polyhedral-shaped CdS decorated ZIF-8 nanocomposites have been prepared by in-situ synthesis. • It exhibits good cyclic stability, with 85.91 % (RAE) capacity retention after 6000 cycles at 5 A/g. • CdS@ZIF-8 achieves a specific capacitance of 1065 Fg−1 at 5 mV/s. With reference to the promising characteristics of metal–organic frameworks (MOFs) and the contributions of nanoparticles (NPs) to their electrochemical activities, the hybrid MOF built with metal sulphides has garnered a lot of attention, primarily as electrode materials in energy storage devices. The polyhedral-shaped CdS enwrapped zeolitic imidazolate framework-8 (ZIF-8) nanocomposites have been prepared by in-situ chemical synthesis. The electrochemical performance was evaluated in 6 M KOH electrolyte, achieving a specific capacitance of 1063.48 Fg−1 at 5 mV/s. The nanocomposite electrode material exhibits good cyclic stability, with 82.32 % (6 M KOH) and 85.91 % (redox additive electrolyte) capacity retention after 6000 cycles at 5 A/g. The energy and power density of the asymmetric supercapacitor were found to be 2.81 Wh/kg and 1785.71 W/kg, respectively. [ABSTRACT FROM AUTHOR]

• An original activated carbon is prepared using golden needle mushroom roots. • As-prepared AC-5 has excellent physical and chemical properties. • The AC-5 electrode exhibits a high specific capacitance of 360.4 F/g. • Such novel activated carbon shows a great potential prospect in supercapacitors. Herein, an original activated carbon (AC) is prepared using golden needle mushroom roots and potassium hydroxide. After carbonization under 500 °C, AC-5 exhibits good graphitization degree, appropriate nitrogen and oxygen elements, large specific surface area, and micro-meso porous structures. Notably, AC-5 as electrodes in supercapacitors has excellent electrochemical performances, e. g. high specific capacitance (360.4 F/g), impressive rate capability (77 %, from 10 mV/s to 200 mV/s), and outstanding cycling durability (99.56 %, after 10,000 cycles). [ABSTRACT FROM AUTHOR]

• The layered β-NiS nanoparticles are successfully synthesized by hydrothermal technique. • The layered structure of β-NiS was confirmed by electron microscopy. • High specific capacitance of 780 F g−1 at 3 mA g−1 was obtained at 3 M KOH solution. • The β-NiS electrode showing excellent retention of 92% after 5000 cycles. At present, there is a significant research focus on development of sulfide based electrode materials for improving the performance of electrochemical supercapacitor (SC). Nickel sulfide (NiS) electrode materials has emerged attention as a promising candidate due to its high value of specific capacitance and outstanding redox activities. This study includes synthesis, characterization, and study the electrochemical properties of the layer structured single-phase β-NiS electrode. At a current density of 3 mA g−1 in 3 M KOH electrolytes, the β-NiS electrode demonstrates an impressive specific capacitance of 780 F g−1 with 92 % cycling capacitance retention after 5000 cycles. [ABSTRACT FROM AUTHOR]

• Indium oxide nanosheet (In 2 O 3 NS) was prepared by the simple hydrothermal method. • High surface area (131.6 m2/g) and short electron diffusion distances improved the electrochemical performance. • The specific capacitance value increased to 927.24 F/g at 0.5 A g−1 current density for In 2 O 3 NS. • In 2 O 3 NS withstands 92.7 % specific capacitance after 8000 cycles. In this research, we synthesized Indium oxide nanosheets (In 2 O 3 -NS) using an easy, cost-effective, and hydrothermal approach. The In 2 O 3 NS modified electrode achieved the highest specific capacitance value of 927.2 F g−1 at 0.5 A g−1 current density in a 2 M KOH electrolyte solution. The electrochemical results indicate that the stability of the In 2 O 3 NS is much greater compared to other reported indium oxide-based nanostructure electrodes. This enhanced cycle stability was seen for a duration of 8,000 cycles at a current density of 1.0 A g−1. In 2 O 3 -NS exhibits favourable characteristics that makes it a viable candidate for use as an electrode material in energy storage for supercapacitor applications. [ABSTRACT FROM AUTHOR]

• Sulfur-rich WS 2 /WO 3 electrodes reached a specific capacitance of 570.1 F/g. • Battery-type behavior in WS 2 /WO 3 electrodes was identified using power law. • WS 2 /WO 3 //AC device revealed energy and power density of 55.6 Wh/kg and 1335 W/kg. • Capacitance retention and columbic efficiency were 87.4% and 99.8% for 5000 cycles. Active sites enriched WS 2 quantum dot decorated WO 3 electrode was designed for supercapacitor application, using hydrothermal and sonication techniques. The WS 2 /WO 3 electrode exhibited a specific capacitance of 570.1 F/g at 1 A/g due to numerous active sites, and facile electrolyte accessibility. The battery-type WS 2 /WO 3 //AC asymmetric supercapacitor device achieved an energy and power density of 55.6 Wh/kg and 1335 W/kg, and a notable retention capacitance and columbic efficiency of 87.4 % and 99.8 % for 5000 cycles at 6A/g, respectively. The results highlight WS 2 /WO 3 as a promising electrode for supercapacitors. [ABSTRACT FROM AUTHOR]

N-doped hierarchical porous carbon as an excellent electrode material in symmetric supercapacitor is fabricated by a facile and green method. [Display omitted] • N-doped porous carbon is prepared from one-step pyrolysis of glycine and Na 2 CO 3. • It exhibits a high capacitance of 207 F/g at 20 A/g in a symmetric supercapacitor. • 99.95% of initial capacitance remains after 10,000 cycles at 5 A/g. • A high energy density of 28.8 Wh/kg is obtained at a power density of 20 KW/kg. N-doped hierarchical porous carbon (NHPC) was facilely fabricated by a one-step pyrolysis of glycine and water-soluble Na 2 CO 3 , which is employed as a renewable water-soluble template without additional corrosive activating reagent. Benefiting from the hierarchical porous structure, high specific surface area (2735 m2 g−1) and the suitable nitrogen content of 3.84 at%, the obtained porous carbon exhibits a high specific capacitance (C sp) of 267 F g−1 at 0.2 A g−1 in a three-electrode system and 201 F g−1 at 0.2 A g−1 in the symmetric supercapacitor. More importantly, it shows an impressive rate capability of 102 % retention at 20 A g−1, outstanding cycling stability with 99.95 % of capacitance retention at 5 A g−1 after 10,000 cycles and a high energy density of 28.8 Wh kg−1 at a power density of 20 KW kg−1 in the symmetric supercapacitor. The results indicate that the synthesized NHPC obtained from this simple synthesis method would be an effective electrode material for symmetric supercapacitors, and this eco-friendly and easily scaled-up approach would provide a valuable strategy for the synthesis of porous carbon materials. [ABSTRACT FROM AUTHOR]

• The hollow cage-like Ni 1 Co 4 -LDH was fabricated using a simple preparation method. • This was the first time that Ni 1 Co 4 -LDH as an electrode for supercapacitor. • The proportions of Ni and Co can influence the supercapacitor abilities for LDHs. We fabricated a nanosphere-like layered double hydroxide (LDH) as a feasible electrode material for electrochemical supercapacitors. The electrochemical performances of Ni x Co y -LDHs with different proportions of Ni and Co were studied to discover the relationship between morphology and supercapacitor property. The Ni 1 Co 4 -LDH showed the best capacitance performance compared to Ni 1 Co 1 -LDH and Ni 4 Co 1 -LDH. The more curly sheets on the surface of Ni 1 Co 4 -LDH may have resulted in the increase of the capacitance due to the increasing conductivity. It is evident that besides changing the state of sheets on the surface of Ni x Co y -LDHs, the Co content may also influence the capacitance performance of Ni x Co y -LDHs. [ABSTRACT FROM AUTHOR]

• Tubular Cu 2 MoS 4 /MWCNTs were prepared as supercapacitor negative electrode material. • Appropriate MWCNTs addition significantly optimized the electrochemical performance. • CMS/MWCNTs-0.15@CC exhibits a highest specific capacitance of 219F g−1 at 0.5 A g−1. • The device with a voltage window of 1.8 V yields an energy density of 24.5 Wh kg−1 at 900 W kg−1. The ternary layered Cu 2 MoS 4 (CMS) has been proven to be a potential supercapacitor negative electrode material. However, its inherent low conductivity and limited diffusion dynamics usually result in unsatisfactory specific capacitance and rate performance. Therefore, hollow tubular CMS and CMS/MWCNTs-0.05, 0.15, 0.25 composite materials were prepared by a one-pot hydrothermal method in this work. The addition of MWCNTs improves the electrical conductivity and provides an efficient three-dimensional electronic transport network. Due to the smallest resistance and optimized porous structure with large surface area, CMS/MWCNTs-0.15@CC exhibits a highest specific capacitance (C s) of 219F g−1 at 0.5 A g−1, which is 2.45 times that of CMS@CC. The assembled Ni-Co-S@CC//CMS/MWCNTs-0.15@CC supercapacitor with a voltage window of 1.8 V yields a maximum energy density of 24.5 Wh kg−1 at 900 W kg−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel copper hydrogen phosphate nano pellets synthesized by chemical bath deposition method. • Copper hydrogen phosphate exhibit high surface area of 61.2 m2/g. • Copper hydrogen phosphate shows a maximum specific capacitance of 874F/g at 0.1 A g−1. • Copper hydrogen phosphate retains 92.8 % of its initial capacitance after 5000 galvanostatic charge–discharge cycles. Herein, the authors disclose for the first time the synthesis of copper hydrogen phosphate (Cu(HPO 4)) material for supercapacitor applications. First, we synthesized Cu(HPO 4) by a facile chemical bath deposition (CBD) method and then it was characterized by several physicochemical techniques. The fabricated Cu(HPO 4) electrode showed superior capacitive performance of 874F/g at 0.1 A/g of current density. Further, Cu(HPO 4) electrode retains a maximum of 93.2% of its original specific capacitance retention over 5,000 galvanostatic charge–discharge (GCD) cycles. [ABSTRACT FROM AUTHOR]

• Et additive could effectively expand ESW of EC from 1.8 to 2.1 V. • EC show an improved energy density with Et additive. • Et additive display many advantages of low cost, high safety. Due to the advantages of high safety, high conductivity and low cost, the supercapacitor with aqueous electrolytes exhibits the great prospects in the future energy storage market. However, the narrow electrochemical stability window (ESW) of electric double-layer supercapacitor leads to its low energy density, which seriously limits its application. Herein, we demonstrate erythritol (Et) additive could efficaciously decrease the water molecules in the solvation sheath and break the hydrogen bond network of aqueous electrolytes, which resulting in expanded ESW. Especially, symmetric supercapacitor based on 37.9% Et additive to 1 M LiTFSI electrolyte expands ESW from 1.8 to 2.1 V, and the energy density increased to 13.3 Wh kg−1 with high specific capacitance of 86.6F g−1 and the capacitance retention rate of 73.8% after 10,000 cycles. Therefore, this study affords an efficient strategy to achieve high energy density aqueous supercapacitor. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ag nanoparticles decorated La 0.85 Sr 0.15 MnO 3 electrode was designed firstly. • The addition of Ag can contribute a small amount of pseudocapacitance. • The as-prepared composite electrode shows superior electrochemical behavior. • It has excellent cycling life with ∼100% capacitance retention after 1000 cycles. • It has energy density of 20.6 Wh·kg−1 and high power density of 8500 W·kg−1. Abstract Ag nanoparticles decorated La 0.85 Sr 0.15 MnO 3 was designed and used as electrode for supercapacitors firstly. Ag nanoparticles not only facilitate to accelerate charge transfer but also contribute a small amount of pseudocapacitance. It shows a high specific capacitance of 186 F·g−1 at 1 A·g−1 and excellent cycling performance. When assembled asymmetric supercapacitor, it possesses maximum energy density of 20.6 Wh·kg−1 at power density of 1700 W·kg−1 within the wide potential window of 1.7 V, as well as 13.4 Wh·kg−1 at 8500 W·kg−1. This work could prompt the development and application of high conductivity nanoparticles modified perovskite in supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights • Electro-active PDPA-PTA-MnO 2 nanohybrid electrode fabricated by electro-chemical deposition. • Superior specific capacitance ∼514 F.g−1 at 5 mVs−1 was achieved. • Nanohybrid electrode shows an excellent capacitive retention and columbic efficiency. Abstract Electrochemical-deposition method was engaged to prepare Fluorine doped Tin oxide (FTO) modified Polydiphenylamine (PDPA)/Phosphotungstic acid (PTA)/Manganese dioxide (MnO 2) nanohybrid (FTO/PDPA/PTA/MnO 2 -ME) Electrode. Nanocomposites structural analysis, morphology, and molecular vibrational studies were characterized through X-ray diffractometer (XRD), Scanning Electron Microscope (SEM) and Fourier Transform Infra read Spectroscopy (FTIR). Recorded XRD and FTIR pattern authenticates the existence of PDPA, PTA, and MnO 2 structures. Cyclic voltammetry (CV) studies performed using electrochemical workstation shows very high specific capacitance value of 514.77 Fg−1 at 5 mVs−1 for the modified hybrid electrode system. The superior capacitive performance, cyclic stability of FTO/PDPA/PTA/MnO 2 electrode was attributed due to the existence and fast reversible multi‐electron redox response of tungsten atoms in PTA along with PDPA-MnO 2 synergistic interaction that augments the electron transfer processes. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Carbon-quantum dot was generated by simple one step process using waste milk. • The CQD exhibited selective sensing of chromium (VI). • Fluorescent probe showed a limit of detection of 14 µM for Cr6+. • Supercapacitor studies delivered specific capacitance of 95 F/g with good stability. Abstract We demonstrate here a sustainable approach to generate carbon-quantum dot (CQD) using denatured (spoiled) milk by a simple one-step hydrothermal method. The unique photophysical property of the CQD has resulted in selective sensing of the chromium ions (Cr6+) as low as 14 µM in control and environmental water samples. The CQD electrode delivered a specific capacitance of 95 F g−1 with an exceptional stability over 1000 cycles. [ABSTRACT FROM AUTHOR]

Highlights • A novel 3D flower-like MoS 2 /N-3DG were fabricated through hydrothermal method. • MoS 2 /N-3DG exhibited relatively good electrochemical properties in supercapacitor. • Synergistic effects between the N-doped graphene and MoS 2 improve the electrochemical performance. Abstract MoS 2 and graphene composites are promising materials for high-performance supercapacitors. Here, we prepared a novel flower-like MoS 2 nanosheet/N-doped 3D graphene (MoS 2 /N-3DG) by hydrothermal method. Electrochemical characterizations indicate that the specific capacitance of MoS 2 /N-3DG can reach up to 301.2 F/g at 0.2 A/g and preserve 82% of the initial capacitance after 1000 cycles at 1 A/g. This result shows that MoS 2 /N-3DG can be applied in supercapacitors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cubic CoMn 2 O 4 supported on Ni foam was prepared through a simple hydrothermal method. • The surface of Ni foam was fully covered by the cubic particles. • CoMn 2 O 4 electrode exhibited excellent specific capacity with good cycling stability. Abstract Cubic CoMn 2 O 4 particles directly grown on Ni foam are developed for asymmetric supercapacitors via a simple hydrothermal method. During electrochemical study, CoMn 2 O 4 electrode exhibits a high capacity of 140.6 mAh g−1 at 1 mA cm−2. A asymmetric supercapacitor containing CoMn 2 O 4 electrode demonstrates a high capacitance of 77.8 F g−1 at 2 mA cm−2. The electrode developed has good potential for practical applications in asymmetric supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights • Hybrid WO 3 –V 2 O 5 nanocomposites were prepared. • Supercapacitor performance was analysed in two electrolytes such as KOH and H 2 SO 4. • The capacitance was enhanced in KOH electrolyte from 44 F/g to 173 F/g. • The capacitance was declined from 246 F/g to 12 F/g in the H 2 SO 4 electrolyte. • WO 3 –V 2 O 5 composites showed capacitance retention of ∼126% up to 5000 cycles. Abstract The rod shape WO 3 –V 2 O 5 hybrid nanocomposites were prepared by microwave assisted wet chemical route. The electrochemical investigations of as-prepared composites were carried in two electrolytes such as KOH and H 2 SO 4 for comparison. Their maximum capacitance was calculated as 44 F/g for WO 3 and 173 F/g for WO 3 –V 2 O 5 composites in KOH electrolyte and its efficiency is 100% up to 5000 cycles and its capacitance retention is ∼126% in KOH electrolyte. In H 2 SO 4 electrolyte, the specific capacitance of WO 3 was recorded as 246 F/g and WO 3 –V 2 O 5 showed poor performance such as less than 12 F/g. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel MnO 2 /g-C 3 N 4 @PPy ternary nanocomposite was designed and fabricated. • The ternary nanocomposite exhibited highly enhanced supercapacitor performance. • The ternary nanocomposite possessed outstanding cyclic stability. Abstract In this work, a novel MnO 2 /g-C 3 N 4 @polypyrrole (PPy) ternary nanocomposite (NC) was fabricated by coupling the MnO 2 nanorods with the two-dimensional g-C 3 N 4 sheets and the conductive PPy. The MnO 2 /g-C 3 N 4 @PPy NC electrode exhibited a high specific capacitance of 274 F g−1 at a current density of 2 A g−1, which was 1.88 times than that of the MnO 2 @PPy NC electrode. The MnO 2 /g-C 3 N 4 @PPy NC electrode also possessed outstanding cyclic stability with 95% capacitance retention after 1000 cycles. The present strategy for fabricating ternary nanocomposite uses low-cost raw materials and simple preparation method, which provides an alternative route to optimize the SC performance of other pseudocapacitive oxides. [ABSTRACT FROM AUTHOR]

Highlights • The as-prepared Ni 3 S 2 /CNTs electrode showed an excellent specific capacitance. • It shows good cycle stability with capacitance retention of 91.5% after 2000 cycles. • There's no binder involved in this method. • The electrodeposition-and-ion exchange technique is suitable for mass production. Abstract We reported a facile and easily controllable electrodeposition-and-ion exchange technique for synthesis of Ni 3 S 2 /carbon nanotubes (CNTs) nanocomposites on the surface of Ni foam for supercapacitor applications. When tested as electrode for a supercapacitor, a large surface area of the Ni 3 S 2 /CNTs hybrid nanoarchitecture was proven and it showed an excellent specific capacitance of 1643 F/g at the current density of 1 A/g, and maintains 999 F/g at 20 A/g. The Ni 3 S 2 /CNTs electrode also displayed good cycle stability with capacitance retention of 91.5% after 2000 cycles in 3 M KOH electrolyte. Because of these outstanding properties, the Ni 3 S 2 /CNTs nanocomposites are becoming promising candidates for the high performance binder-free supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Highlights • All-organic composite of COF and PANI was prepared. • TpPa-COF@PANI-based supercapacitor showed high capacitance. • TpPa-COF@PANI-based supercapacitor showed great long-term cycling performance. Abstract A novel all-organic composite of covalent organic framework (COF) and polyaniline (PANI) was successfully designed and prepared. By combining the highly porous and redox active TpPa-COF and conductive PANI, TpPa-COF@PANI composite electrodes showed greatly improved performance in supercapacitor application. After 30,000 cycles, the capacity retention rate of the battery is as high as 83%, which indicates that the electrode has great cycling stability. The strategy reported in this work may shed light on the design of new redox active COFs based faradaic supercapacitors and have a great potential for other electrochemical devices. [ABSTRACT FROM AUTHOR]

Highlights • Ultrathin carbon nanosheet-supported Ni quantum dot hybrids were fabricated. • Starch is used as the source of ultrathin carbon nanosheet. • The hybrids exhibited high specific capacitance and excellent rate capability. • The hybrids exhibited outstanding cycling stability. Abstract Ultrathin carbon nanosheet-supported Ni quantum dot hybrids (C-Ni-QDs) were synthesized via a two-step process. The obtained hybrid materials exhibited high specific capacitance of 1120 F g−1 at 2 A g−1 and excellent rate capability with a retention ratio of 81.3% at 20 A g−1. Besides, the C-Ni-QDs hybrids also exhibited outstanding cycling stability with a capacitance retention of 97.0% after 2000 cycles. These results indicated that C-Ni-QDs hybrids could be a promising material for supercapacitors. [ABSTRACT FROM AUTHOR]

Highlights • Carbon-coated copper sulfide nanocomposite prepared via two-step sulfidation. • Cu 7 S 4 /C nanocomposite is ∼100 nm in size. • Cu 7 S 4 /C electrode exhibits highest capacitance (321.9 F g−1) at 0.5 A g−1. Abstract Metal-organic framework (MOF)-derived carbon-coated metal sulfides are a popular research area for energy storage, owing to their highly reactive nature and universal electrochemical activity. A simple and efficient method for the preparation of carbon-coated copper sulfide via a calcining-hydrothermal process using an MOF template is presented in this paper. The transmission electron microscope (TEM) imaging indicates that the cobble-like Cu 7 S 4 nanopolyhedra are ∼100 nm in size, and are interconnected by amorphous carbon. Electrochemical analysis shows that the Cu 7 S 4 /C electrode possesses the highest capacitance, 321.9 F g−1 (80.5 mAh g−1 in capacity), at a current density of 0.5 A g−1, and achieves nearly 78.1% capacitance retention after 3000 cycles, suggesting its holds promise for application in battery-type electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NDG reveals a double-layer structure of graphene upper layer and thick graphite lower layer. • Specific capacitance of CuCo 2 S 4 on NDG was twice higher than on Ni foam at 50 A g−1. • CuCo 2 S 4 @NDG//rGO asymmetric supercapacitor revealed 58.4 W h kg−1 at 797 W kg−1. Abstract CuCo 2 S 4 synthesized on the nitrogen-doped double-layer graphite (NDG) inter-layer revealed more uniform and smaller size than synthesized directly on Ni foam. From electrochemical measurements, the specific capacitance of CuCo 2 S 4 @NDG electrode was 1244 F g−1 at a current density of 50 A g−1, which was twice higher than the CuCo 2 S 4 @Ni electrode. In addition, the reduced graphene oxide (rGO) was used to assemble CuCo 2 S 4 @NDG//rGO asymmetric supercapacitor, revealing a high energy density (58.4 W h kg−1) for practical applications. Significantly, the NDG inter-layer improved the properties of asymmetric supercapacitor at high-rate and high energy density conditions effectively. [ABSTRACT FROM AUTHOR]

Selecting suitable electrode materials is the key to develop high-performance supercapacitors. Herein, we report the niobium nitride (NbN) thin films prepared by reactive magnetron sputtering and investigate their electrochemical performances when used as supercapacitor electrodes. NbN thin film electrodes can achieve the optimal electrochemical performance with a volumetric capacitance of 707.1 F cm −3 and an outstanding cycling stability (remaining 92.2% after 20,000 cycles). Such impressive properties render the NbN thin films qualified as the promising candidates for supercapacitors or other energy storage systems. [ABSTRACT FROM AUTHOR]

A simple chemical precipitation method is applied to synthesize pure-phase KCoF 3 with size in the range of 1–5 μm, which is further used as electrode material in supercapacitors. The cyclic voltammetry, electrochemical impedance spectroscopy measurements, and galvanostatic charge-discharge cycling test measurements are carried out for the KCoF 3 electrode, and the results show a specific capacitance of 286 F⋅g −1 at 0.5 A⋅g −1 in 6.0 M KOH electrolyte. Particularly, KCoF 3 electrode exhibits long cycling lifetime with 96% retention of initial capacitance after 1000 cycles at a current density of 5.0 A⋅g −1 . [ABSTRACT FROM AUTHOR]

• 2D Mxene-Ti 3 C 2 intercalated ZnCo 2 O 4 nanowires have been successfully synthesized. • The introduction of Ti 3 C 2 accelerates the dynamics of electrochemical reactions. • An ASC exhibits high energy density and 90.5% capacity retention after 10,000 cycles. It is necessary to develop hierarchical structured materials with excellent electrochemical characteristics and stability for energy storage. In this work, we synthesize a novel structure of ZnCo 2 O 4 /Ti 3 C 2 on Ni foam by a simple hydrothermal method. The frameworks accelerates the kinetic of the electrochemical reaction and promotes the transfer of electrons. The cycling stability of the device maintains 108.2% after 4000 cycles. The result indicates that the prepared sample is an excellent candidate material for energy storage. [ABSTRACT FROM AUTHOR]

We have synthesized book-like Co 3 O 4 microstructures on copper form by hydrothermal and annealing process, which can be directly used as binder-free, excellent rate capability and long-life supercapacitor electrode. The random slant book-like Co 3 O 4 microstructures were uniformly grown on the Cu substrate, and the electrode exhibited a high specific capacitance of 736.25 F g −1 at a current density of 1 A g −1 , good coulombic efficiency of 82.6%, excellent rate capability and 78.13% capacity retaining after 5000 cycles of charge and discharge, demonstrating a great potential in high power storage devices application. [ABSTRACT FROM AUTHOR]

Transition metal nitrides have attracted significant attention for energy storage applications due to their unique structural, electronic and catalytic properties. In this study, chromium nitride thin films have been deposited on 304L steel substrate by reactive magnetron DC sputtering and then it used as a supercapacitor electrode without additional processing. These films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray analysis (EDAX, Oxford Instruments), and X-ray photoelectron spectroscopy (XPS) techniques. XRD spectra shows the (1 1 1), (2 0 0), and (2 2 0) planes of the cubic phase of CrN film. The Raman spectra of CrN thin film shows the acoustic vibrational mode at 238 cm −1 , and optical mode at 619 cm −1 . The FE-SEM images show the columnar structure of CrN thin films. The electrochemical properties were evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The working electrode showed remarkably high specific capacitance of 41.6 F/g at the scan rate of 5 mV/s. The working electrode depicted high capacitance retention of 87% up to 2000 cycles. The electrochemical performance of the CrN showed that they can be used as potential electrode material for electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

In this work, supercapacitive properties of un-doped and Cu doped Mo 3 N 2 thin films developed by reactive magnetron co-sputtering technique are reported. X-ray diffraction (XRD) investigation confirmed the cubic phase of Mo 3 N 2 and the addition of Cu to Mo 3 N 2 did not change the crystal structure. The presence of Cu in this Mo 3 N 2 was further confirmed by energy dispersive spectroscopy (EDX). The electrochemical supercapacitive performance of the needle/cone shaped thin film electrodes were investigated using cyclic voltammetry and galvanostatic charge-discharge techniques. The measurements showed an areal capacitance of 173.4 mF cm −2 for the un-doped and 619.5 mF cm −2 for the Cu doped Mo 3 N 2 at a scan rate of 5 mV s −1 in 1 M KOH and the excellent cycling stability of 80% capacitance retention over 2000 cycles. The results suggested that the prepared Mo 3 N 2 based electrodes are excellent candidate materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Co 3 S 4 nanoneedle decorated NiCo 2 O 4 nanosheets are successfully prepared by a two-step hydrothermal process for supercapacitors. The NiCo 2 O 4 nanosheets are served as ideal backbones to enhance the surface area and provide more electroactive sites for faradaic reaction. The optimized NiCo 2 O 4 /Co 3 S 4 electrode shows a high specific capacity of 1468 F g −1 at the current density of 1 A g −1 . When assembled an asymmetric supercapacitor, the device exhibits high energy density of 14.0 Wh kg −1 at 400 W kg −1 , and retains 84.7% of the capacity after 3000 cycles. [ABSTRACT FROM AUTHOR]

Sphere-feature MoSe 2 has been synthesized by using a facile hydrothermal method. The electrochemical properties of the as-prepared materials have been investigated for supercapacitors. Electrochemical measurements show that MoSe 2 spheres exhibit a specific capacitance of 243 F/g at 0.5 A/g, and still kept 90.3% capacitance after 1000 cycles at 1 A/g, indicating MoSe 2 sphere could be a promising candidate for high-performance supercapacitor applications. [ABSTRACT FROM AUTHOR]

A novel method of preparing cube-like MnO 2 by MnCO 3 was firstly reported. The MnCO 3 used as self-sacrificing template was synthesized via a polyol process. The porous, hierarchical MnO 2 microcubes with uniform size were obtained after thermal treatment from as-prepared MnCO 3 in air atmosphere. X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) together recorded the composition and structure information. Electrochemical tests showed that the highest specific capacitance can reach up to 152 F g −1 and hardly any loss was observed after 100 cycles at different current densities. The results suggested that this well-designed material may have a promising application in energy storage of supercapacitor. [ABSTRACT FROM AUTHOR]

Vertically assembled two-dimentional materials have great scientific and technological promise. In this work, altrathin atom doped graphitic carbon nitride (g-C 3 N 4 ) was synthesised via thermal treatment of thiourea and KBr/NaBr. Free-standing manganese dioxide nanoflakes were uniformly grown on K/Na doped g-C 3 N 4 through hydrothermal reaction. The K doped g-C 3 N 4 @ MnO 2 has a specific capacitance twice higher than that of pure g-C 3 N 4 @ MnO 2 . This unique design brought excellent specific capacitance (375 F g −1 ) and cycle stability, which showed that atom doping is an effective approach to enhance electrochemical performance. In addition, the low cost, facial synthesis and small amount of addings make this strategy an optimized approach to construct g-C 3 N 4 based electrode materials. [ABSTRACT FROM AUTHOR]

In this paper, the synthesis of ZnO tetrapods and its application as electrode materials for high-performance supercapacitors have been reported. The galvanostatic charge-discharge measurement results show that the specific capacitances of the ZnO tetrapods-based electrodes increase with the decrease of the current densities. The maximum capacitance is 160.4 F g –1 at the current density of 1.0 A g –1 . The Ragone plot shows that the ZnO tetrapods have excellent supercapacitive performance. Moreover, the cyclic stability is measured by the galvanostatic charge/discharge technique at a constant current density of 10.0 A g –1 in 1.0 M Na 2 SO 4 aqueous electrolyte. The results show the excellent capacitance retention of 94.3% over 1000 cycles. In a word, ZnO tetrapods should be the ideal potential electrode materials for low-costing and effective electrochemical supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • NGO/NiWO 3 /PANI nanocomposite was prepared by Hydrothermal method. • Current density of NGO/NiWO 3 /PANI electrode is significantly increased. • Specific capacitance of NGO/NiWO 3 /PANI electrode is about ∼1380 F/g at 0.5 A/g. • NGO/NiWO 3 /PANI electrode material displays excellent cycling stability. Hybrid supercapacitors signify a potential candidate for highly stable energy storage devices because of their excellent power density, low cost, and inherent safety. Hydrothermal method was used to synthesize NGO (Nitrogen doped graphene oxide)/NiWO 3 (nickel tungstate)/PANI (polyaniline)) nanocomposite (NC). GCD analysis offers noticeable enhanced specific capacitance of 1380 F/g as compared to NiWO 3 (670 F/g) and displays the cycle stability for 10 000 cycles with 92.6 % retention of capacitance at the current density of 0.5 A/g, and also shows a high energy density of 47.8 W h kg−1. These obtainable outcomes propose that NGO/NiWO 3 /PANI can be considered an efficient electrode for highly stable supercapacitors. [ABSTRACT FROM AUTHOR]

• The NiCoS@NiMo-LDH hierarchical composites are synthesized on Ni foam. • NiCoS@NiMo-LDH nanostructure provides abundant active sites and enough ion channels. • The binder-free NiCoS@NiMo-LDH electrode exhibits excellent electrochemical properties. • The fabricated ASC device exhibits a high energy density and good stability. Ni(OH) 2 ·0.75H 2 O nanosheets embedded with NiMoO 4 nanoparticles (NiMo-LDH) supported by nickel cobalt sulfur (NiCoS) nanorods were prepared by a multi-step hydrothermal method, which provides an effective channel for ion transport and abundant active sites for charge storage. The NiCoS@NiMo-LDH electrode exhibited a very high capacitance of 1302.5 μAh cm−2 at 10 mA cm−2, with 54 % capacitance retention observed at 50 mA cm−2. The asymmetric supercapacitor (ASC) assembled with the NiCoS@NiMo-LDH as the positive electrode and active carbon (AC) as the negative electrodes which exhibits an energy density of 1096.6 μWh cm−2 at a power density of 2.8 mW cm−2 along with good stability of 86.67 % after 5000 cycles. [ABSTRACT FROM AUTHOR]

• Fe 3 O 4 /C was synthesized for the supercapacitor with expired ferrous gluconate as the precursor; • Fe 3 O 4 /C powder appeared as the hierarchical dumbbell-like morphology; • The capacitances of three-electrode and two-electrode systems were 490.2F/g and 210.2F/g; • The unique hierarchical dumbbell-like morphology was responsible for high capacitances; • The desirable results indicated high feasibility of the circular economy of the wastes. Hierarchical dumbbell-like Fe 3 O 4 /C powder was synthesized for the supercapacitor electrode by the solvothermal reaction and subsequent calcination. Resultantly, the reversible capacitances of the three-electrode and symmetric two-electrode capacitors were 490.2 F/g and 210.2 F/g, respectively, higher than those in literatures, possibly due to the unique hierarchical dumbbell-like structure with the easier access and penetration of the electrolyte to the electrode. Moreover, the symmetric Fe 3 O 4 /C two-electrode system exhibited the remarkable cycle stability at 5.0 A/g and high energy density of 34.3 Wh/kg at 1003.9 W/kg, indicating high feasibility for the application in high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

We have successfully synthesized a metal-organic framework and then researching its structure and morphology by scanning electron micrographs (SEM) and transmission electron microscopy (TEM). Furthermore, we fabricated Zn 0.65 Ni 0.35 O by using the metal-organic framework as precursor for supercapacitor. The Zn 0.65 Ni 0.35 O electrode exhibited a maximum specific capacitance of 471.1 F g −1 at the current density of 1 A g −1 , which still remained at 81.3% over 1000 cycles. [ABSTRACT FROM AUTHOR]

Hollow activated carbons (HACs) with unique through-pore structure derived from reed straw were prepared with KOH activation. The amount of activating agent greatly affected the properties of the HACs. When the KOH content was three times that of the carbonized reed straw, the HACs exhibited a large specific surface area of 2387 m 2 g −1 and outstanding electrochemical performance. The specific capacitance of the assembled electrodes reached 355 F g −1 at 1 A g −1 . Moreover, a high specific capacitance of 290 F g −1 was retained even at a high current density of 30 A g −1 , implying excellent rate performance. These results clearly demonstrate the potential of reed straw-based HACs for use in supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

Exploring novel porous carbon-based materials with improved electrochemical performance is of great importance for their practical application in energy storage systems. Herein, we report a one-step strategy for the synthesis of porous carbon constructed by highly interconnected micro-/mesoporous thin walls, which exhibits excellent capacitive performance in organic electrolyte. The specific capacitance can reach to 208 F/g at 0.75 A /g and still sustain 188 F/g at 10 A/g while the IR drop only increasing from 0.01 to 0.22 V. All of these results suggesting that the as-synthesized porous carbon material is very attractive as electrode material for high-performance supercapacitor. [ABSTRACT FROM AUTHOR]

Simple hydrothermal method was adopted to synthesize zero dimensional 14-facets (6 squares and 8 cuboids) NiCo 2 S 4 cubohexa-octahedral (NCS-COH) shaped nanostructures for high performance supercapacitor properties. The as-prepared nanostructures were characterized using X-ray powder diffraction, scanning and transmission electron microscopy. A plausible formation mechanism was also proposed along with crystal structure of NCS-COH. The exceptional architectures fashioned an ultrafast electron transfer during electrochemical reaction. The NCS-COH electrode exhibited a high specific capacitance of 835 at 1 A/g and capacitance retention of 92.7% at 10 A/g after 5000 cycles. [ABSTRACT FROM AUTHOR]

Smart textiles are attracting increasing attention due to their tremendous applications in wearable devices. Herein, we report a flexible and conductive textile prepared via simple “dipping and drying” method with Ag nanowires (Ag NWs) ink. The obtained Ag NWs/cellulose textiles have very high conductivity(sheet resistance 0.2 Ω/sq) and excellent chemical and mechanical stabilities, showing great potential in wearable energy storage and photothermal conversion. The supercapacitor made from the Ag NWs/cellulose textile showed a higher capacitance (159 F g −1 ) than the textiles functionalized with single-walled carbon nanotube (SCNT) and graphene. Besides, they presented excellent photothermal conversion property with about 50% improvement in temperature compared with pure textile. These multifunctional textiles would provide new opportunities for flexible and wearable electronics and sensors. [ABSTRACT FROM AUTHOR]

This work demonstrates the fabrication of micro carbon fibers with hierarchical nanostructures of nickel-carbon nanotubes by electroless plating and chemical vapor deposition. Characterizations show that the micro coaxial fibers have 1400 times larger surface area, and 100 times larger electrochemical capacitance than pristine carbon fibers, while their mechanical strength has only 8% degradation. These outstanding properties make the micro coaxial fibers promising for applications in flexible or wearable supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

The novel route for preparation of high-performance porous carbon from corn starch by a one-step process of chemical activation with H 3 PO 4 was studied in this paper. The resulting porous carbon showed a high specific surface area of 1167 m 2 g −1 and a large pore volume of 1.80 cm 3 g −1 . The maximum specific capacitance was up to 162 F g −1 at a current density of 0.625 A g −1 , which was higher than commercial carbon (100 F g −1 ). Meanwhile, the electrode exhibited larger energy density (22.5 Wh kg −1 at a power density of 313 W kg −1 ) and longer cycle stability with above 93% capacitance retention after 5000 cycles. The better capacitive behavior was ascribed to unique pore structure, which indicated the porous carbon will be an ideal electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]

In this paper, we reported a facile route for the fabrication of TiO 2 /Fe 2 O 3 composite on the surface of Ti-15Fe alloy foil prepared by arc melting through simple high-temperature oxidation, which was used as an electrode for supercapacitor. TiO 2 and Fe 2 O 3 grew together and in coarse short rod shape. The electrode exhibited excellent electrochemical performance with areal capacitance of 840 mF cm − 2 at current density of 1 mA cm −2 as well as superior long-term cycling life of 120% capacitance retention after 3000 cycles. These results demonstrate the potential of oxidation products of Ti alloys as high-performance electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Supercapacitors composed of MoS 2 typically suffer from inferior cycling stability because of aggregation and pulverization of the active particles during cycling. In order to alleviate volume expansion of the active particles and restrain aggregation and pulverization during cycling, hollow MoS 2 nanomaterials are synthesized by a simple hydrothermal method and the structure and supercapacitance characteristics are studied. The nanostructured MoS 2 particles, which has a hexagonal phase without impurities, has a diameter between 0.5 and 2 µm and contains many irregular nanosheets manifesting as a flower-like structure with a thickness of several nanometers. As the electrode in a supercapacitor, the hollow nanostructured MoS 2 shows excellent capacitance characteristics including good cycling ability. [ABSTRACT FROM AUTHOR]

Hexapod-like two dimensional transition metal dichalcogenide nickel diselenide (NiSe 2 ) structures was synthesized by a facile hydrothermal approach and investigated its electrochemical performance as a supercapacitor electrode for the first time. The obtained material was characterized by XRD, XPS and TEM analysis. The results confirmed the presence of orthorhombic phase of NiSe 2 in the synthesized hexapod-like NiSe 2 structures. The fabricated NiSe 2 electrode on graphite foil exhibited a specific capacitance of 75 F g −1 with good cyclic retention of 94% at a current density of 1 mA cm −2 after 5000 charge-discharge cycles. Our results indicate that the synthesized hexapod-like NiSe 2 structures hold as a promising candidate for the supercapacitor applications. [ABSTRACT FROM AUTHOR]

A novel bio-inspired hollow activated carbon microtubes (HACMs) was prepared from low-cost, renewable biomass willow catkins by low temperature pre-carbonization combined with KOH chemical activation and used as supercapacitor electrode materials. The as-prepared HACMs exhibit hollow fiber-like structure with thin wall thickness of less than 1 µm, high microporosity surface area (997 m 2 g −1 ) and concentrated pore size distribution (1–2 nm). The electrochemical measurement results demonstrate that the HACMs electrode materials have high gravimetric capacitance of 306 F g −1 superior to most of the previously reported activated carbons and outstanding volumetric capacitance of 303 F cm −3 . [ABSTRACT FROM AUTHOR]

[Display omitted] • The Co 3 O 4 with hexagonal morphology are designed. • Facile synthesis of calcining precursors is prepared the hexagonal Co 3 O 4. • The hexagonal Co 3 O 4 exhibits excellent electrochemical performance. The key to improving the energy density of supercapacitors is to enhance the electrochemical properties of the electrode materials by optimizing the preparation process and rationally designing the material structure. In this work, hexagonal Co 3 O 4 are derived by calcination of the precursors in the air, which are used as electrode materials for high-performance supercapacitors. The specific capacity of the hexagonal Co 3 O 4 electrode reaches 216.4 F g−1 at the current density of 1 A g−1. It is worth mentioning that it achieves a capacity retention rate of 112.5% and a coulombic efficiency of 99.5%, after 10,000 cycles. [ABSTRACT FROM AUTHOR]