Electrodes For High-performance Asymmetric Supercapacitors Research Articles

Typha orientalis leaves derived P-doped hierarchical porous carbon electrode and carbon/MnO2 composite electrode for high-performance asymmetric supercapacitor

Sustainable biomass-derived carbon used as electrode features the concept of green chemistry. Herein, Typha orientalis leaves, which show tunable porous structure with high phosphorus content, were used as precursor to prepare P-doped hierarchical porous carbon material and then acted as negative electrode for supercapacitor. Different with the traditional activation methods, the biomass was pretreated by ZnCl2 then activated with KOH (Zn-K-ATC). Owing to the hierarchical porous structure, large specific surface area (1975 m2 g−1) and pseudocapacitance provided by P self-doping, Zn-K-ATC had a high specific capacitance of 324 F g−1 at 1 A g−1 in 1 M KOH. Zn-K-ATC was further used as support to grow MnO2 (Zn-K-ATC/MnO2) as the positive electrode material with a specific capacitance of 384 F g−1 at 1 A g−1 in 1 M Na2SO4. The assembled Zn-K-ATC/MnO2//Zn-K-ATC asymmetric supercapacitor device had a voltage window of 2 V with a high energy density of 46 Wh kg−1 at 1000 W kg−1. This work gives a systematic research and complete inspection on the preparation of supercapacitor from biomass-derived materials, which expects to provide a valuable method for the preparation of green, low-cost, high-performance supercapacitor materials.

Sea urchin-shaped Fe2O3 coupled with 2D MXene nanosheets as negative electrode for high-performance asymmetric supercapacitors

Fe2O3 is one of promising negative materials for supercapacitors (SCs), because of its low cost and high theoretical value of specific capacitance. However, the inferior conductivity and insufficient ionic diffusion rate of Fe2O3 will seriously hinder the electrochemical performance of Fe2O3, resulting in limiting its practical application in SCs. Herein, a sea urchin-like 3D Fe2O3 was synthesized via hydrothermal methods. And then, the 2D Ti2C3Tx MXene nanosheets with high conductivity closely self-assemble on the surface of Fe2O3 to provide efficient pathways for the rapid electrons transport. In addition, the sea urchin-like structure of Fe2O3 can facilitate the rapid diffusion of the electrolyte to accelerate faradaic reaction. The optimized Fe2O3/MXene composite as electrode material exhibits a high specific capacitance of 486.3 F g−1 at current density of 1 A g−1, and excellent cycling stability with 95.7% capacity retention after 5000 charge/discharge cycles. Furthermore, an asymmetric supercapacitors (ASCs) device was assembled by using Fe2O3/MXene composite as anode and MnO2 as cathode, showing a high energy density of 32.2 Wh kg−1 at the power density of 900.6 W kg−1, and remarkable long-term durability (95.7 % capacitance retention after 5000 cycles). This work demonstrates an effective approach of integrating the sea urchin-like Fe2O3 with 2D MXene nanosheets to fabricate Fe2O3/MXene composite for high-performance SCs.

A dual NiCo metal-organic frameworks derived NiCo2S4 core-shell nanorod arrays as high-performance electrodes for asymmetric supercapacitors

The structural stability of electrode materials is the crux of significantly improve the electrochemical performance of pseudocapacitor electrodes. Herein, we demonstrate the preparation of NiCo2S4 with core-shell and micro-porous structure on nickel foam as an efficient anode material for asymmetric supercapacitor (ASC) via hydrothermal and co-sulfurization processes. The NiCo2S4 electrode shows a remarkable specific capacitance of 850.2 C g−1 at 1 A g−1, and retains 93.6 % original capacitance after 5000 cycles. Furthermore, the NiCo2S4 electrode also have excellent electrochemical performance when used as an anode of asymmetric NiCo2S4//Active Carbon (AC) supercapacitor, which generates an energy density as 38.1Wh Kg−1 at 700 W kg−1 and 84.3% capacity retention after 5000 cycles. This work provide an efficiently method to suppress volume expansion during sulfuration reaction by core-shell structure, which potential application in transition metal sulfides electrode materials in electrochemical energy storage and conversion devices.

Electrodeposition of vanadium pentoxide on carbon fiber cloth as a binder-free electrode for high-performance asymmetric supercapacitor

Electrodeposition technique is a convenient and robust approach for the development of transition metal oxides as electrodes, particularly for supercapacitor applications. However, achieving uniform coating is difficult and relies on the constrained deposition parameters. Herein, we fabricated the binder-free spiral rope-like structured V2O5 on carbon fiber cloth (CFC) by simple and versatile electrodeposition method for high performance asymmetric supercapacitors. The deposition rate of V2O5 nanostructures on CFC was controlled by varying the electrodeposition duration. The resultant optimum duration (30 min) of the binder-free V2O5@CFC-30 electrode showed an excellent performance with a high areal capacitance of 354 mF/cm2 in 1 M Na2SO4 aqueous electrolyte. Furthermore, the asymmetric supercapacitor (ASC) was developed using V2O5@CFC-30 as a positive electrode and O, N, S enriched activated carbon (O, N, S@AC) as a negative electrode. The ASC demonstrated a maximum device-specific capacitance of 57 F/g, excellent cyclic stability (~94%) even after 10,000 cycles and maximum specific energy (17.7 Wh/kg) and power (2728 W/kg). Furthermore, the flexible supercapacitor delivered maximum specific energy (13 Wh/kg) and power (3871 W/kg) with an outstanding capacity retention of 91% over 4000 cycles. This research makes the electrodeposition of V2O5 ideally suited for a binder-free, high performance supercapacitor applications.

High mass loading flower-like MnO2 on NiCo2O4 deposited graphene/nickel foam as high-performance electrodes for asymmetric supercapacitors.

The implementation of high mass loading MnO2 on electrochemical electrodes of supercapacitors is currently challenging due to the poor electrical conductivity and elongated electron/ion transport distance. In this paper, a NiCo2O4/MnO2 heterostructure was built on the surface of three-dimensional graphene/nickel foam (GNF) by a hydrothermal method. The petal structured NiCo2O4 loaded on graphene played a wonderful role as a supporting framework, which provided more space for the growth of high mass loading MnO2 microflowers, thereby increasing the utilization rate of the active material MnO2. The GNF@NiCo2O4/MnO2 composite was used as a positive electrode and achieved a high areal capacitance of 1630.5 mF cm−2 at 2 mA cm−2 in the neutral Na2SO4 solution. The asymmetric supercapacitor assembled with the GNF@NiCo2O4/MnO2 positive electrode and activated carbon negative electrode possessed a wide voltage window (2.1 V) and splendid energy density (45.9 Wh kg−1), which was attributed to the satisfactory electroactive area, low resistance, quick mass diffusion and ion transport caused by high mass loading MnO2.

Construction of self-supported bimetallic MOF-mediated hollow and porous tri-metallic selenide nanosheet arrays as battery-type electrodes for high-performance asymmetric supercapacitors

Architecting the highly conductive polyphase transition metal selenide with a carbonaceous nanostructure onto a 3D substrate has been acknowledging the appealing task for the development of auspicious electrode materials for energy storage devices.

Reagent-assisted hydrothermal synthesis of NiCo2O4nanomaterials as electrodes for high-performance asymmetric supercapacitors

Spinel nickel cobaltate nanoneedle arraysin situsynthesized by a CTAB assisted hydrothermal method show an energy density of 22.5 W h kg−1at 800 W kg−1.

Sulfur-Doped Nickel–Cobalt Double Hydroxide Electrodes for High-Performance Asymmetric Supercapacitors

In this work, an effective strategy was proposed to improve the electrochemical performance of nickel–cobalt layered double hydroxide (NiCo-LDH) by controlling the sulfur doping. The prepared NiCo-...

Scanty graphene-driven phase control and heteroatom functionalization of ZIF-67-derived CoP-draped N-doped carbon/graphene as a hybrid electrode for high-performance asymmetric supercapacitor

Zeolitic imidazolate framework (ZIF)-derived materials have been explored as promising electrode for energy storage, owing to their tunable composition, high porous structure, and heteroatom-based active sites. Herein, we report cobalt phosphide-draped N-doped carbon/graphene hybrid (CoP-NPC/GS) synthesized from ZIF-67 precursor via a single-step in-situ carbonization and phosphidation. The CoP-NPC/GS hybrid performed as a promising positive electrode with superior electrochemical performance – high capacitance (165 F g−1 at 7 A g−1 compared to 97 F g−1 for CoP-NPC), enhanced rate capability, and promoted cycling stability (~88% after 10,000 cycles). Excellent performance of the CoP-NPC/GS was derived from scanty graphene (2 wt%)-driven compositional variation, which promotes the redox-active CoP phase and higher nitrogen content offering enhanced electronic conductivity. Besides, CoP-NPC/GS performed well as a negative electrode, derived from double-layer capacitance of porous carbon, realizing a capacitance of ~71 F g−1 at 1 A g−1 but inferior to CoP-NPC, which was regulated by pyridinic nitrogen-induced pseudocapacitance. A fabricated CoP-NPC/GS||CoP-NPC asymmetric device displayed an energy density of 10 Wh Kg−1 at 700 W kg−1, with excellent cyclability (~100%) till 11,000 cycles. This study clarifies the role of scanty graphene on the phase control and heteroatom functionalization of phosphide-based electrode, beneficial for enhanced supercapacitive performance.

Vertical carbon skeleton introduced three-dimensional MnO2 nanostructured composite electrodes for high-performance asymmetric supercapacitors

We successfully fabricate a hierarchical three-dimensional (3D) nanocomposite rGO/C/MnO2 composed of 2D/1D rGO/C and MnO2 nanosheets. The vertical porous carbon decorated rGO is obtained by growing covalent organic frameworks (COFs) arrays on the surface of GO with further calcination. After the introduction of the special rGO/C porous substrate, the rGO/C/MnO2 nanocomposite shows the more stable nanostructure, the larger specific surface area (~129.79 m2 g−1), and the better electrical conductivity. Benefiting from these, the rGO/C/MnO2 electrode possesses high specific capacitance (215.2 F g−1 at 0.5 mA cm−2 (~0.15 A g−1)), good rate capability and long cycling stability (72% capacitance retention after 2500 cycles). Solid-state asymmetric supercapacitors are assembled with rGO/C/MnO2 as the positive electrode material, activated carbon (AC) as the negative electrode material, and polyvinyl alcohol (PVA)/LiCl as the gel electrolyte. The device can provide a high power density of 3.6 kW kg−1 at a current density of 20 mA cm−2 (~3.2 A g−1) and a high energy density of 21.2 W h kg−1 at a current density of 1.0 mA cm−2 (~0.16 A g−1). Furthermore, two rGO/C/MnO2//AC asymmetric supercapacitors in series power a commercial LED more than 40 s.

Binary nickel ferrite oxide (NiFe2O4) nanoparticles coated on reduced graphene oxide as stable and high-performance asymmetric supercapacitor electrode material

Transition metal oxides are nowadays one of the most important materials in the manufacture of capacitive electrodes. The most important problems with these materials for applied energy storage devices are low specific energy and poor electrical conductivity. In this research nickel ferrite nanoparticles (NiFe2O4) and also hybrid of NiFe2O4/rGO are synthesized by hydrothermal method and characterized by XRD, Raman, and XPS analysis. The amount of porosity and specific surface area is studied by BET analysis as and surface morphology is studied by SEM and TEM. To investigate the effect of adding rGO to NiFe2O4 nanoparticles, from a hybrid electrode superconducting electrochemical tests are performed, including CV, EIS, and charge-discharge. This electrode with a capacitance of 584.63 F/g and capacitance retention of 91% after 2000 consecutive cycles can be a tempting option for supercapacitor applications.

Free-standing NiCoSe2 nanostructure on Ni foam via electrodeposition as high-performance asymmetric supercapacitor electrode

Designing a high-energy-density and power-density electrode for supercapacitors has become an increasingly important concept in the energy storage community. In this article, NiCoSe2 nanostructures were electrodeposited on nickel (Ni) foam and directly used as electrodes for supercapacitors. The effect on the morphology and electrochemical performance of NiCoSe2 prepared under different scan rates was measured through scanning electron microscopy and various electrochemical measurements. The resultant NiCoSe2 prepared with 5 mV s−1 exhibits a cross-linked porous nanostructure and a high specific capacitance of 2185 F g−1 at a current density of 1 A g−1. Taking advantage of these features, an ASC is constructed by using NiCoSe2 on Ni foam as the positive electrode and an active carbon electrode as the negative electrode with 3 M KOH as the electrolyte. The ASC displays a high-energy density of 41.8 Wh kg−1, an ultrahigh power output of 8 kW kg−1, as well as a long cycling life (91.4% capacity retention after 10 000 cycles). The excellent electrochemical performance makes the porous NiCoSe2 nanostructures a promising alternative in energy storage devices.

Vapor solid phase grown hierarchical CuxO NWs integrated MOFs-derived CoS2 electrode for high-performance asymmetric supercapacitors and the oxygen evolution reaction

Designing and exploring a simple, novel, and smart synthetic concept to fabricate highly efficient and dual-function electrode material at an optimum cost for green energy harvesters has been a long-standing challenge. Herein, for the first time, we investigated a simple and smart concept to fabricate dual-function vapor solid phase grown copper oxide nanowires (CuxO NWs) integrated metal-organic frameworks-derived (MOFs) hollow and porous cobalt sulfide (CuxO NWs@CoS2) hybrid nanostructures as an effective binder-free electrode for supercapacitors and the OER. When utilized as an electrode material for supercapacitors, the CuxO NWs@CoS2 hybrid electrode displayed an ultrahigh specific capacity of 331.6 mAh/g (volumetric capacity of 2.46 mAh/cm3) with an outstanding rate capability of 67% even at a high current density of 50 mA/cm2; moreover, the electrode possessed a long-term durability of 100.2% after 10,000 cycles. An all-solid-state asymmetric device (CuxO NWs NWs@CoS2//Fe2O3/rGO aerogels) delivered a specific energy density of 49.8 Wh/kg. In addition, the oxygen evolution activity of the CuxO NWs@CoS2 electrode was also investigated and the electrode demonstrated superior catalytic properties compared to other formulations. This investigation emphasizes a novel synthetic approach and its multifunctional applicability in energy storage and generation devices.

Nickel-cobalt-molybdenum sulfides with adjustable morphology via coprecipitation and hydrothermal conversion as high-performance electrodes for asymmetric supercapacitors

The morphology of a multicomponent transition metal sulfide electrode plays a vital role in the electrochemical properties of advanced supercapacitors. However, the control of hybrid metal sulfide morphology during preparation remains a challenge. This study demonstrated the controlled synthesis of NixCo1-xMoSy (NCMS) nanorods, nanoplate-on-nanoparticles and nanoparticles by adjusting the NaOH concentration of the ethanol-water solution used in the hydrothermal step of a simple coprecipitation-hydrothermal method. The NCMS electrode materials with the nanoplate-on-nanoparticle and nanoparticle morphologies had a higher available surface area for electrolyte penetration and a larger number of pseudocapacitive redox reaction sites during the charge/discharge process in alkaline solution. The NCMS electrode exhibited a high specific capacity of 227 mAh g−1 at 1 A g−1, a good rate capability with 76.7% retention at increasing current densities from 1 to 20 A g−1, and a high cyclability with 70.48% retention at 5 A g−1 after 1000 cycles. An asymmetrical supercapacitor assembled using NCMS as the positive electrode and active carbon as the negative electrode had an energy density of 55 Wh kg−1 at a power density of 850 W kg−1 (1 A g−1). These results demonstrated the excellent applicability of this NCMS electrode material in high-performance supercapacitors.

Hollow-structured NiCoP nanorods as high-performance electrodes for asymmetric supercapacitors

One-dimensional hollow-structured NiCoP nanorods are synthesized via Kirkendall effect resulting from different diffusion rates of Ni and Co ions at 350 °C, using NaH2PO2 as a phosphorization agent. Various techniques were used to study the formation mechanism of hollow NiCoP nanorods which structure and crystallinity could be effectively tuned by adjusting phosphorization time. Capacitance of NiCoP reaches 273.4 μAh cm−2 at a current density of 30 mA cm−2 with a rate retention of 85.6%. Specific capacitance of an asymmetric supercapacitor cell (ASC) where NiCoP sample was used together with activated carbon reached 264.6 μAh cm−2 at 2 mA cm−2 and decreased to 213.2 μAh cm−2 with current density rising to 30 mA cm−2. The ASC possesses quite high energy- and power densities, compared to previously reported results, which demonstrates applicability of hollow NiCoP nanorods for electrochemical energy storage.

Novel Ag configurations decorated CuO hybrid electrode for high-performance asymmetric supercapacitor

In situ integration of highly conductive metals into transitional metal oxide electrodes with enabling fast electron transfer kinetics is a plausible technique for improving electrochemical performances of electrode materials. Herein, for the first time, we demonstrate a rational configuration of conductive Ag flakes (FAg) that directly grown on CuO nanorods by in situ chemical approach. The obtained FAg–CuO hybrid electrode demonstrates a superior specific capacitance of 812 F/g at a current density of 2 A/g which is retained of about 110.37% after 5000 cycles. The solid-state asymmetric supercapacitor (ASC) based on FAg–CuO and active carbon is further fabricated. The ASC device similarly demonstrates remarkable performances with a high energy density of 40.02 Wh/kg at a power density of 1095.8 W/kg and also excellent cycling ability with stable capacitances output beyond 5000 cycles. The obtained superior performances are attributed to the rational Ag configurations which could effectively reduce the interfacial barriers and meanwhile enhance the electron transport and ion diffusion, with achieving the high-efficiency utilization for the active materials during Faradaic redox reactions.

Construction of a Ternary Nanocomposite, Polypyrrole/Fe–Co Sulfide-Reduced Graphene Oxide/Nickel Foam, as a Novel Binder-Free Electrode for High-Performance Asymmetric Supercapacitors

The development of asymmetric supercapacitors requires the design of electrode construction and the utilization of new electroactive materials. In this regard, an effective strategy is the loading ...

Hierarchical CoS@MoS2 core-shell nanowire arrays as free-standing electrodes for high-performance asymmetric supercapacitors

The freestanding hierarchical core-shell nanoarchitectures exemplify the substantial interest in the development of next-generation electrode materials for energy storage systems . Herein, the hierarchical 3D CoS@MoS2 nanowire arrays (NWAs) are synthesized through a cost-effective hydrothermal process and followed by an effective sulfurization. The structural and morphological investigations of hierarchical 3D CoS@MoS2 NWAs are carried out for each stage. The 3D CoS@MoS2 NWAs yields a high specific capacity of 374.75 mA h g−1 and an areal capacity of 1.39 mA h cm−2 at a current density of 4 mA cm−2, exceptional rate capability (∼70.1% retention of the capacity at 20 mA cm−2), and remarkable cycling performance (∼96.2% retention of the capacity after 10,000 consecutive charge-discharge cycles), which are superior to the corresponding CoS nanowires and MoS2 nanosheets counterparts. The assembled CoS@MoS2//Fe2O3@rGO asymmetric supercapacitor (ASC) exhibits a broader working potential window of 1.7 V, ultrahigh energy density of 95.7 W h Kg−1 at the power density of 711.2 W kg−1, and super-long cycling stability (∼95.5% retention of capacity after 10,000 cycles), demonstrating that the hierarchical 3D CoS@MoS2 NWAs are promising as potential candidates for hig-performance SCs.

Mn3O4 tetragonal bipyramid laden nitrogen doped and hierarchically porous carbon composite as positive electrode for high-performance asymmetric supercapacitor

Nanostructured metal oxides have shown outstanding promise for electrochemical energy storage, but are usually limited to low rate capability and poor cycling performance caused by irregular shapes and aggregation of nanoparticles at high mass loading (>1 mg cm−2). To solve these problems, we report the design of a novel Mn3O4 tetragonal bipyramid laden nitrogen doped and hierarchically porous carbon (Mn3O4 TB/NHPC) composite with higher mass loading (～5 mg cm−2) for high-performance energy storage. The homogeneous dispersion of Mn3O4 TBs on NHPC with 3D architecture provides excellent electron transfer, and its hierarchically porous structure with large mesopore volume facilitates rapid ion transport. To achieve wide working potential window, an asymmetric supercapacitor of 1.8 V is assembled with Mn3O4 TB/NHPC composite and NHPC as the positive and negative electrode, respectively. Benefiting from these advantages, the supercapacitor exhibits excellent rate capability (80% of the capacitance retention from 0.5 to 10.0 A g−1) and high energy density (34.7 Wh kg−1 at 450 W kg−1). More importantly, the assembled device demonstrates a splendid cycling performance (97% capacitance retention after 10000 cycles). Morphology controlled Mn3O4 laden porous carbon composites with remarkable capacitive performance inspire us to develop superior electrode materials for energy storage.

Improvement of electrical performance by surface structure of Ni-material as a high-performance asymmetric supercapacitor electrode

Binder-free Ni-material array electrodes on Ni-foam are fabricated using a facile hydrothermal method for high-performance supercapacitors. Instead of a binder, urea is added to increase the adhesion of Ni-foam as both the substrate and electrode material. In this paper, we present the contribution of urea to the formation of the material. The surface characteristics and the electrical properties of the Ni-material array change with the amount of urea. When 2.4 g of urea is added to the sample for the first time, a Ni(HCO3)2 microrod electrode is obtained; it shows large wire growth on the Ni-foam, which can be explained about the abnormal grain growth behavior because there is little energy barrier for atomic attachments with a disordered or rough interface atomic structure. Its specific capacitance is 346 F g−1 at a current density of 3 A g−1. In contrast, when the amount of urea is reduced to 0.8 g, a Ni2(CO3) (OH)2 array electrode is produced; it exhibits a nano-size wire array and a specific capacitance of 833.2 F g−1 at a current density of 3 A g−1. Thus, it is confirmed that the large surface area of Ni2(CO3) (OH)2 exhibits outstanding electrical properties. And, the fabricated asymmetric supercapacitor of Ni2(CO3) (OH)2 composite as the positive electrode and graphene as the negative electrode, which has a high energy density of 22.1 W h kg−1 at a power density of 673.1 W kg−1. In addition, this obtained asymmetric supercapacitor can turn on the LED light.