Electrode Material For Asymmetric Supercapacitors Research Articles

Conductive Ni2P nanosheet arrays-carbon nanofibers as binder-free pseudocapacitive electrode materials

• The Ni 2 P-CNFs has high conductivity, ample active sites and good redox activity. • The Ni 2 P-CNFs is a flexible material that can directly use as self-supported supercapacitor electrode materials without the binders. • The Ni 2 P-CNFs electrode materials exhibited excellent specific capacitance of 1057.5 F g −1 at the current density of 0.5 A g −1 , good rate capability and prominent cycle stability. • The Ni 2 P-CNFs//CNF asymmetric supercapacitor displayed the energy density of 8.5 Wh kg −1 at the power density of 353.3 W kg −1 . Flexible carbon nanofibers (CNFs) were prepared by electrospinning of polyacrylonitrile, followed by peroxidation and carbonization treatments. Then, conductive Ni 2 P nanosheet arrays were vertically grown on the CNFs by phosphorizating of Ni-precursor on its surface. The obtained CNFs loaded by conductive Ni 2 P nanosheet arrays (Ni 2 P-CNFs) were directly used as flexible pseudocapacitive electrode materials. Results showed that the Ni 2 P-CNFs electrode displayed remarkable specific capacitance of 1057.5 F g −1 at 0.5 A g −1 , good rate capability of 387.5 F g −1 at 50 A g −1 and prominent capacitance retention of 89.7% after 3000 cycles at 5 A g −1 . Asymmetric supercapacitor based on Ni 2 P-CNFs and CNFs were fabricated, which showed energy density of 8.5 Wh kg −1 at power density of 353.3 W kg −1 and the capacitance was kept at 92.5% after 3000 cycles at 2 A g −1 . Therefore, the conductive Ni 2 P-CNFs would be a promising pseudocapacitive electrode materials for asymmetric supercapacitor.

Pseudo spin-ladder CaCu2O3 nanostructures as potential electrode material for asymmetric supercapacitors

Supercapacitors have attracted noteworthy attention due to their high power density and excellent cyclic stability than batteries, despite the limited energy density of the supercapacitors which discourages their practical application. Herein, we have demonstrated the application of a pseudo spin-ladder CaCu2O3 (2-leg) nanostructures as an efficient electrode for the fabrication of a high-performance asymmetric supercapacitor (ASC). CaCu2O3 has received a lot of attention due to its unique magnetic properties and its close relation to high temperature superconductors. The number of Cu-O chains (legs) found in the spin ladder structure of this compound is responsible for its low dimensional magnetism with the Neel temperature of ∼25 K. Electrochemical analysis has revealed that the specific capacitance (specific capacity) of CaCu2O3 based supercapacitor is 205.45 F g−1 (92.45 C g-1) at a current density of 1.5 A g−1 and furthermore CaCu2O3 nanostructures exhibited excellent cyclic stability with capacitance retention of 104% after 10000 continuous cycles. The assembled ASC device (CaCu2O3//AC (activated carbon)) delivered the energy density of 11.8 Wh kg-1 at the power density of 362.5 W kg-1. Evidently, the energy density of 2.21 Wh kg-1 is still retained even at a high power density of 3625 W kg-1. The obtained results demonstrated that the spin-ladder CaCu2O3 electrode materials are potential candidates for high-energy storage applications.

Sacrificial template synthesis of hollow-structured NiCoP microcubes as novel electrode materials for asymmetric supercapacitors.

Transition bimetallic phosphides with optimal composition and morphology are efficient electrocapacitive materials for asymmetric supercapacitors (ASCs). Herein, a unique bimetallic phosphide, NiCoP, with a hollow microcube structure, was synthesized by a sacrificial template method followed by phosphorization calcination. Impressively, the resulting nanosheet-based NiCoP hollow microcube (NiCoP-HMC) electrode exhibits a remarkable specific capacity of 1088.9 C g-1 at 1 A g-1 and superior cycling performance (the capacity remains 90.2% after cycling for 10 000 cycles at 6 A g-1), owing to its unique morphology, the superiority of bimetallic phosphides, and its battery type feature. Furthermore, an ASC was fabricated by using the obtained NiCoP-HMCs as the positive electrode and using active carbon (AC) as the negative electrode. The assembled ASC device delivers a high specific energy of 78.2 W h kg-1 at a specific power of 799.9 W kg-1 and has 84.8% capacity retention over 10 000 cycles at 8 A g-1, demonstrating its great potential for applications in the field of high-capacity supercapacitors. These results illustrate NiCoP-HMCs as promising positive electrode materials for supercapacitors.

Self-Assembly and Controllable Synthesis of High-Rate Porous Nico2s4 Electrode Materials for Asymmetric Supercapacitors

Self-Assembly and Controllable Synthesis of High-Rate Porous Nico2s4 Electrode Materials for Asymmetric Supercapacitors

1T-VS2/MXene Hybrid as a Superior Electrode Material for Asymmetric Supercapacitors: Experimental and Theoretical Investigations

The present work explores the electrochemical energy storage performance of Ti3C2Tx (MXene) and 1T-VS2 nanosheet hybrids synthesized by a simple in situ hydrothermal method. Different analytical me...

Effect of neutral electrolytes on vanadium dioxide microspheres-based electrode materials for asymmetric supercapacitors

Different neutral electrolytes (0.5 M K2SO4, 1 M Li2SO4, 1 M Na2SO4, and 1 M NaNO3) were used to investigate the electrochemical performances of vanadium dioxide (VO2) successfully synthesized via a solvothermal process. X-ray diffraction (XRD) results for the VO2 material revealed a monoclinic crystal structure phase A and field emission scanning electron microscopy (FESEM) images showed that the sample is formed of microspheres-like morphology with an assembly of nanograins on their surfaces. Electrochemical investigation of as-prepared sample was done in three-electrode configurations. The highest specific capacitance of 163.1 F g−1 was recorded with 0.5 M of K2SO4 and the lowest value of 44.5 F g−1 with 1 M Li2SO4 at a specific current of 0.5 A g−1 in a stable potential window of 0.8 V. The synthesized vanadium dioxide (VO2 (A)) as a positive electrode and peanut shell derived activated carbon (PS-AC) as a negative electrode were used to assemble asymmetric supercapacitors (VO2//PS-AC) in 0.5 M K2SO4 electrolyte. This asymmetric device recorded a specific energy of 25.8 W h kg−1 with a corresponding specific power of 425 W kg−1 at 0.5 A g−1 in a cell potential of 1.7 V. It also showed a good columbic efficiency of 99.8% and a capacitance retention of 75% up to 10,000 charge-discharge cycles at a specific current of 5 A g−1. Overall, the VO2 microspheres//PS-AC asymmetric supercapacitor revealed excellent electrochemical performance in the neutral medium electrolyte and thus a potential candidate for use in other integrated energy systems.

Facile synthesis of cobalt Disulfide/Carbon nanotube composite as High-performance supercapacitors electrode

Transition metal sulfides are widely used in energy conversion and storage devices due to their distinguished electrochemical activity. In particular, cobalt disulfide (CoS2) shows potential as a good electrode material owing to its low cost and good stability. Here, a series of CoS2/CNT composites with different contents of carbon nanotubes (CNTs) was prepared through a one-step hydrothermal method and used as electrode materials for asymmetric supercapacitors. Their electrochemical performance was also studied. Results show that compared with other composite materials, CoS2/CNT-20 exhibited a larger specific capacitance of 823F g−1 at 0.5 A g−1, satisfactory cycling stability of 93.86% capacitance retention after 7000 cycles at 3 A g−1, and a high energy density of 27.7 Wh kg−1 at the power density of 749.8 W kg−1. These findings imply their promising application in energy storage devices.

MnCoP hollow nanocubes as novel electrode material for asymmetric supercapacitors

• Hierarchical nanosheet-based MnCoP hollow nanocubes were synthesized and characterized. • MnCoP has uniform morphology, electrical conductivity, structural stability and large surface area. • As a battery-type positive electrode, MnCoP showed a maximum capacity of 879 Cg −1 at 2 Ag −1 . • Superior cycling stability of 94.4% capacitance retention after 6,000 cycles achieved. • Maximum energy density of 66.98 Wh Kg −1 and power density of 16466 W Kg −1 were found. Fabrication of novel and efficient electrodes for green and renewable hybrid energy storage systems is an effective approach to deal with energy crisis. In this work, hierarchical nanosheet-based MnCoP hollow nanocubes electrode with the battery type feature has been successfully synthesized by a simple hard and soft acid-base (HSAB) approach followed by a heat treatment. By taking advantage of the remarkable merits including uniform morphology, electrical conductivity, structural stability, large surface area as well as the battery type feature, the nanosheet-based MnCoP hollow nanocubes electrode exhibits enhanced electrochemical performance with high specific capacity of 879C g −1 at 2 A g −1 excellent cycling stability of 94.4% capacity retention after 6,000 cycles, and maximum energy and power density of 66.98 Wh Kg −1 and 16446 W Kg −1 , respectively.

Effect of soft template on nickel-cobalt layered double hydroxides grown on nickel foam as battery-type electrodes for hybrid supercapacitors

Nickel-cobalt layered double hydroxides (NiCo-LDHs) are successfully synthesized on nickel foam by the simple hydrothermal process, with polyvinylpyrrolidone (PVP), cetyltrimethyl ammonium bromide (CTAB), polyvinyl alcohol (PVA), and sodium dodecyl sulfate (SDS) as template agents, respectively. The prepared NiCo-LDHs present different morphology and outstanding electrochemical performances. Particularly, the NiCo-LDHs samples with CTAB as template agents (NC-C) exhibit high specific capacity (869.48 C g−1 at 1 A g−1) and excellent durability (88.23% capacity retention after 2000 cycles). Furthermore, the hybrid supercapacitors (HSCs) device based on NC-C and activated carbon electrodes deliver an energy density of 48.34 Wh kg−1 at a power density of 799.84 W kg−1 and satisfactory cycle stability (90.83% capacity retention after 2000 cycles). These properties indicate that the prepared materials could become ideal electrode materials for asymmetric supercapacitors.

Over-Reduction-Controlled Mixed-Valent Manganese Oxide with Tunable Mn2+/Mn3+ Ratio for High-Performance Asymmetric Supercapacitor with Enhanced Cycling Stability.

Manganese oxides composed of various valence states Mnx+ (x = 2, 3, and 4) have attracted wide attention as promising electrode materials for asymmetric supercapacitor. However, the poor electrical conductivity limited their performance and application. Appropriate regulation content of Mnx+ in mixed-valent manganese oxide can tune the electronic structure and further improve their conductivity and performance. Herein, we prepared manganese oxides with different Mn2+/Mn3+ ratios through an over-reduction (OR) strategy for tuning the internal electron structure of mixed-valent manganese, which could make these material oxides a good platform for researching the structure-property relationships. The Mn2+/Mn3+ ratio of manganese oxide could be precisely tuned from 0.6 to 1.7 by controlling the amount of reducing agent for manipulating the redox processes, where the manganese oxide electrode with the most appropriate Mn2+/Mn3+ ratio, as 1.65 (OR4) exhibits large capacitance (274 F g-1) and the assembling asymmetric supercapacitors by combining OR4 (positive) and the commercial activated carbon (as negative) achieved large 2.0 V voltage window and high energy density of 27.7 Wh kg-1 (power density of 500 W kg-1). The cycle lifespan of the OR4//AC could keep about 92.9% after 10 000-cycle tests owing to the Jahn-Teller distortion of the Mn(III)O6 octahedron, which is more competitive compared to other work. Moreover, a red-light-emitting diode (LED) can easily be lit for 15 min by two all-solid supercapacitor devices in a series.

CuS cluster microspheres anchored on reduced graphene oxide as electrode material for asymmetric supercapacitors with outstanding performance

Transition metal chalcogenides have been considered as promising electrode materials for high-performance supercapacitors owing to their exceptional electrical conductivity, ultrahigh specific capacity, etc. Herein, CuS/rGO composite electrode material has been rationally prepared by using a facile and efficient strategy, and the synergistic effect of CuS and rGO on the enhanced electrochemical performance is explored. The CuS/rGO electrode with diffusion-controlled feature can deliver a high specific capacitance of 1918.6 F g− 1 F g − 1 at 1 A g − 1 and as well as a long cycling life with 95.4% retention after 5000 cycles at 10 A g − 1. Charge storage analysis reveals that the dominant diffusion-controlled feature of CuS/rGO electrode is observed. Additionally, the as-synthesized asymmetric supercapacitor by using CuS/rGO electrode exhibited a maximum energy density of 51.1 Wh kg− 1 at 799.9 W kg− 1 and a maximum power density of 16007.9 W kg− 1 (for an energy density of 36.0 Wh kg− 1). Besides, it displays excellent cyclic stability with 91.3% capacity retention after 10,000 cycles at 10 A g− 1. These remarkable electrochemical performances demonstrate that CuS/rGO composite has excellent potential applications in high-efficient electrochemical supercapacitor.

2D porous layered NiFe2O4 by a facile hydrothermal method for asymmetric supercapacitor

2D porous layered NiFe2O4 nanostructures were successfully synthesized via a facile hydrothermal method and subsequent high-temperature calcination route. Benefiting from its advantages of the unique 2D porous layer nanostructures with large specific surface area (116.35 m2 g−1) and abundant mesoporosity, the as-prepared NiFe2O4 electrode displayed a high specific capacitance of 425.62 F g−1 at a current density of 1 A g−1, excellent capacitance retention rate of 75.26% at current density of 16 A g−1 compared with 1 A g−1, and long cycle life (88.61% of the maximum capacitance value after 3500 cycles) through the three-electrode system test. Moreover, an aqueous asymmetric supercapacitor based on the 2D porous layered NiFe2O4 as a positive electrode and the activated carbon as a negative electrode was assembled for the first time. The NiFe2O4//AC ASC device delivered a high specific capacitance of 105.94 F g−1 at a current density of 1 A g−1 in a voltage window of 1.6 V, and could achieve a high energy density of 37.67 Wh/kg, excellent rate capability, and good long-term cycling stability (84.21% retention after 4000 cycles). These results demonstrated that the as-fabricated 2D porous layered NiFe2O4 could be one of the promising electrode materials for asymmetric supercapacitors.

Sponge-like NiCo2S4 nanosheets supported on nickel foam as high-performance electrode materials for asymmetric supercapacitors

Herein, binder-free sponge-like NiCo2S4 nanosheets supported on Ni foam with ultra-high mass loading were synthesized via a facile one-step hydrothermal route.

Development of hierarchically structured nanosheet arrays of CuMnO2-MnxOy@graphene foam as a nanohybrid electrode material for high-performance asymmetric supercapacitor

Transition-metal-based nanomaterials are preferred for electrochemcial supercapacitor applications owing to their low purchasing cost, facile synthesis process and high theoretical electrochemcial performance. However, these materials can not translate their excellent theoretical performance into commendable experimental values. In these circumstances, supercapacitors based on new class of highly conductive and electroactive hybrid nanomaterial are recommended. Herein, for the first time, 2D CuMnO2-MnxOy@graphene foam (GF) hybrid nanomaterial is constructed as a novel electrode material for asymmetric supercapacitor application. The CuMnO2-MnxOy@GF hybrid nanomaterial displays an excellent areal capacitance of 7.82 F cm−2 at a current density value of 3 mA cm−2, while it also maintains maximum areal capacitance of 67.51% at 60 mA cm−2. The CuMnO2-MnxOy@GF hybrid nanomaterial retains a high capacitance of 92.15% after maximum 10,000 cycles. A high-performance asymmetric supercapacitor device is assembled based on CuMnO2-MnxOy @GF and sulfur-nitrogen-codoped graphene nanosheets (SN-GNs) as positive and negative electrode materials, respectively. The CuMnO2-MnxOy @GF//SN-GNs ASC device shows an ultra-high energy density value of 81.4 W h kg−1 at a minimum power density of 809.5 W kg−1. The CuMnO2-MnxOy @GF//SN-GNs ASC device retains a specific capacitance of 88.88% after 10,000 cycles. The CuMnO2-MnxOy@GF hybrid nanomaterial is beneficial to promote asymmetric supercapacitor device with an excellent electrochemcial performance.

Swift heavy ion beam modified MoS2- PVA nanocomposite free-standing electrodes for polymeric electrolyte based asymmetric supercapacitor

Swift heavy ion (SHI) beam irradiation technique is one of the sophisticated techniques used for modifying material properties to design efficient devices. In this report, the casted MoS2- PVA nanocomposite films have been irradiated with 80 MeV C6+, 100 MeV Si9+, and 120 A g9+ ion beams to achieve enhanced conductivity and have been exploited as an electrode material for asymmetric supercapacitor. PVDF-HFP: TPAI gel polymer electrolyte having 3 wt.% TPAI content showed the highest conductivity and was chosen for the iodide redox gel polymer electrolyte system. The pristine MoS2-PVA nanocomposite films having an electrical conductivity of 2.5E-5 S/cm exhibited specific capacitance of 65.27 F/g whereas the films irradiated with 120 MeV Ag9+ ion beams showed an electrical conductivity of 9.7E-3 S/cm and enhanced specific capacitance of 186.67 F/g. The enhanced capacitance is attributed to the high current density generated due to the increased conductivity of the electrodes.

A facile synthesis of boron nitride supported zinc cobalt sulfide nano hybrid as high-performance pseudocapacitive electrode material for asymmetric supercapacitors

High specific energy, extended working potential, and elevated cyclic stability are the major issues regarding supercapacitor technology. To fabricate a competent hybrid supercapacitor electrode, it is necessary to combine both pseudocapacitive and electric double-layer capacitor (EDLC)-type materials smartly. The prime objective of this work is to develop a high-performance asymmetric supercapacitor (ASC) device with long-term cycling stability and extended working potential. Accordingly, an ASC device was fabricated by using sphere-like pseudocapacitive Zinc Cobalt sulfide (ZCS) in combination with other pseudocapacitive [Boron Nitride (BN) and Polypyrrole (PPY)] and EDLC-type [CNT] materials. The synthesized quaternary composite exhibited maximum specific capacitance (Csc) of 534 and 785 F/g in aqueous (1 M KCl) and organic [(1 M TEABF4 in acetonitrile (ACN)] electrolytes, respectively. Moreover, it also exhibited excellent cycling stability (capacitance retention of 106% after 10,000 charge/discharge cycles) in aqueous electrolyte. Apart from this, a theoretical study has been exposed to determine the EDLC and pseudocapacitive contribution of the electrode materials. Further, the ASC device exhibited an extended working potential (worked up to 1.8 V) with high specific energy of 49.6 Wh/kg in organic electrolyte. With these promising electrochemical performance, this mixed metal chalcogenide based ASC is considered as potential candidate for next-generation supercapacitors.

Cobalt based Metal Organic Framework/Graphene nanocomposite as high performance battery-type electrode materials for asymmetric Supercapacitors

Recently, development of advanced materials of metal-organic frameworks (MOFs) has attracted attention for the fabrication of supercapacitors (SCs) because of their high surface area and high level of porosity. However, poor electrical conductivity and weak mechanical properties of the MOFs have restricted their applications in the field. In this study, a one-step, in-situ synthesis of Cobalt-based MOF with graphene (CoMG nanocomposite) was employed to overcome the poor properties of MOFs. Accordingly, when the nanocomposite (CoMG5) was use as a supercapacitor electrode material, a specific capacitance (CS) of 549.96 F g−1 was observed in a three-electrode system with 6 M KOH electrolyte when scan rate was 10 mV s−1 in the cyclic voltammetry (CV) test. This CS value is higher than that of pristine Co-MOF (CoM) and graphene (G) owing to the synergistic effects between CoM and G in the nanocomposite. Moreover, the CoMG5//carbon active (CoMG5//CA) asymmetric supercapacitor assembled in a 6 M KOH electrolyte with the potential window of 1.7 V showed a high energy density of 8.10 Wh kg−1, the power density of 850 W kg−1 and good cycle lifetime, i.e. after 1000 charge/discharge cycles at 1 A g−1, 78.85% of its initial specific capacitance was retained. So that, two devices connected in series could light up an LED for more than 10 minutes continuously. This suggests that CoMG5 nanocomposite is possibly a new promising alternative material for production of high-performance energy storage devices.

ZnS-Ni7S6 Nanosheet Arrays Wrapped with Nanopetals of Ni(OH)2 as a Novel Core-Shell Electrode Material for Asymmetric Supercapacitors with High Energy Density and Cycling Stability Performance.

Supercapacitors possess minimum energy density, lower rate capability, and inferior long-term cycling stability performance, and these issues have restricted their practical applications. In these circumstances, supercapacitors based on a new class of hybrid nanomaterial are strongly desirable. Herein, for the first time, a complex nanoarchitecture comprised of a ZnS-Ni7S6/Ni(OH)2 core/shell is constructed via a multistep hydrothermal process. The ZnS-Ni7S6/Ni(OH)2 core/shell nanoarchitecture illustrates a commendable areal capacitance of 13.55 F cm-2 at a lower current density value of 5 mA cm-2, respectively. The ZnS-Ni7S6/Ni(OH)2 core/shell hybrid nanomaterial maintains a high cycling stability performance of 95.12% after a maximum 10 000 number of cycles. Moreover, the asymmetric supercapacitor device made up of ZnS-Ni7S6/Ni(OH)2 and nitrogen-sulfur-codoped graphene nanosheets (NSGNs) delivers an ultrahigh energy density value of 68.85 W h kg-1 at a power density of 700.16 W kg-1. The cycling stability of the ZnS-Ni7S6/Ni(OH)2//NSGN asymmetric supercapacitor was performed and was 91.79% after 10 000 GCD cycles. The ZnS-Ni7S6/Ni(OH)2 core/shell hybrid electrode material has helped in promoting an asymmetric supercapacitor device with an elevated performance and can be considered as a potential electrode material to develop energy storage devices in the future.

Realizing an Asymmetric Supercapacitor Employing Carbon Nanotubes Anchored to Mn3O4 cathode and Fe3O4 Anode

A facile route to anchor pseudocapacitive materials on multi-walled Carbon Nanotubes (CNTs) to realize high-performance electrode materials for Asymmetric Supercapacitors (ASCs) is reported. The anchoring process is developed subsequent to direct decomposition of metal-hexacyanoferrate complex on the CNT surface. Transmission electron microscopy (TEM) analysis reveals that the nanoparticles (NPs) are discretely attached over CNT surface without forming a uniform layer, thus making nearly entire NP surface available for electrochemical reactions. Accordingly, CNT-Mn3O4 nanocomposite cathode shows significantly improved capacitive performance as compared to pristine CNT electrode, validating the efficacy of designing the composite electrode. With CNT-Fe3O4 nanocomposite as paired anode, the hybrid ASC delivers a specific capacitance of 135.2 F/g at a scan rate of 10 mV/s within a potential window of 0-1.8V in the aqueous electrolyte and retains almost 100% of its initial capacitance after 15000 cycles. The serially connected ASCs can power commercial LEDs and mobile phones reflecting their potential in next-generation storage applications.

Decoration of NiCoP nanowires with interlayer-expanded few-layer MoSe2 nanosheets: A novel electrode material for asymmetric supercapacitors

Tailoring hybrid electrodes with rational microstructure and appropriate active components is crucial for developing high performance supercapacitors (SCs). Herein, we assemble highly conductive arrayed NiCoP nanowires on flexible carbon cloth substrate (CC) and subsequently decorate the nanowires with MoSe2 nanosheets to form a 3D NiCoP@MoSe2 heterostructure for high performance SCs. The interactionbetween tightly bound NiCoP and MoSe2 results in the reduction of the number of MoSe2 layers from more than 15 to 2–3, and expansion of the interplanar spacing from 0.65 nm to 0.76 nm. Such heterostructure integrates the advantages of more accessible active sites of the interlayer-expanded few-layer MoSe2 nanosheet, the high conductivity of the arrayed NiCoP nanowires, and the 3D open nanostructures, achieving the synergistic effects of the directionally efficient electron transfer and efficient utilization of active sites. Consequently, the CC supported binder-free electrode of NiCoP@MoSe2 exhibits a high specific areal (gravimetric) capacitance of 5613.5 mF cm−2 (2245.4 F g−1) at a current density of 1 mA cm−2 and outstanding long-term durability. A flexible asymmetric supercapacitor constituted of NiCoP@MoSe2 as positive electrode and active carbon (AC) as negative electrode achieves a high energy density of 55.1 Wh kg−1 at the power density of 799.8 W kg−1 and a remarkable cycling stability of 95.8% capacitance retention after 8000 cycles. This study provides a new route for the designing of novel nanoarchitecture with multi-components in energy storage applications.