Binder-free Supercapacitor Electrode Research Articles

Cobalt-Based Metal-Organic Framework Electrodeposited on Nickel Foam as a Binder-Free Electrode for High-Performance Supercapacitors

Cobalt-Based Metal-Organic Framework Electrodeposited on Nickel Foam as a Binder-Free Electrode for High-Performance Supercapacitors

A cobalt-based metal–organic framework electrodeposited on nickel foam as a binder-free electrode for high-performance supercapacitors

Co-MOF/NF has been prepared by cathodic electrodeposition using highly active cobalt as a surface modifier, and shows improved capacitance performances.

Fabrication of Nico Layered Double Hydroxide on Carbon Fiber Paper as High Performance Binder-Free Electrode for Supercapacitors

Fabrication of Nico Layered Double Hydroxide on Carbon Fiber Paper as High Performance Binder-Free Electrode for Supercapacitors

Manganese-doped tungsten disulfide microcones as binder-free electrode for high performance asymmetric supercapacitor

Manganese-doped tungstate sulfide (Mn-WS2) microcones were developed with varying levels of Mn, grown directly on electrically conductive Ni foam, and used as binder-free electrode material for supercapacitors. The experimental research indicates that Mn-WS2 microcones has significantly improved electrochemical activity and cyclic stability compared with pure WS2 due to additional ion diffusion channels. A strong synergy between the transitional metal ions in Mn-WS2 remarkably improved the redox activity, rate capability, and cycling stability. The Mn-WS2 microcones had a high specific capacitance of 107.79 mA h g−1 at 1 A g−1, a high rate capability of 75.18% at 20 A g−1, and 96.1% capacitance retention after 10,000 charge–discharge cycles. The effect of Mn ions on the electrochemical performance of WS2 microcones was also studied in detail. The enhanced electrochemical performance of the electrode can be attributed to the unique structural features of WS2 microcones arrays grown in Ni foam, which allow the surface of WS2 to be highly accessible to electrolyte ions. Furthermore, an all solid state asymmetric supercapacitor (ASCs) assembled with Mn-WS2 microcones as anode and GO/Fe3O4 cathode (Mn-WS2//PVA-KOH// GO/Fe3O4) delivered high specific energy of 70.65 W h kg−1 at 997.41 W kg−1. These results confirm that Mn-WS2 with outstanding electrochemical properties could be a promising electrode material for practical application in electrochemical energy storage field.

Network-like FeNb2O6 nanostructures on flexible carbon cloth as a binder-free electrode for aqueous supercapacitors

Because of their multiple chemical valence states, multi-element transition metal oxides can undergo reversible redox reactions between the different valence states during charging and discharging. However, the low electrical conductivity of transition metal oxides limits the rate of electron transfer. The combination of transition metal oxides with three-dimensional carbon substrate is a promising but extremely challenging strategy to prepare high specific capacitance, stable and environmentally friendly supercapacitor electrode materials. Here we report a facile one-step vapor deposition synthesis of network-like FeNb2O6 nanostructures directly growing on flexible carbon cloth (CC). The as-prepared FeNb2O6/CC composite has good electrical conductivity, and the network-like structure also makes it have large specific surface area. Resultantly, the composite exhibits an high specific capacity of 365.9 mAh g−1 at a current density of 2.5 A g−1. And at the current density of 25 A g−1, a specific capacity of 75.9 mAh g−1 can still be maintained.

Embellishing hierarchical 3D core-shell nanosheet arrays of ZnFe2O4@NiMoO4 onto rGO-Ni foam as a binder-free electrode for asymmetric supercapacitors with excellent electrochemical performance

Tailoring hierarchical hybrid core-shell electrodes with impartial microstructural features and excellent electroactive constituents is crucial for the design of high-performance supercapacitors (SCs). Herein, for the first time, we fabricate uniformly aligned porous ZnFe2O4 (ZFO) nanosheet arrays onto reduced graphene oxide-garnished conductive Ni foam (rGO-NF) substrates and subsequently embellish the first layer of ZFO nanosheets with morphology-controlled secondary NiMoO4 nanosheets to achieve a hierarchical 3D core-shell structure of ZnFe2O4@NiMoO4 nanosheet arrays (NSAs) onto rGO-NF for SC applications. Improving the synergistic effect of the core-shell nanoarchitecture with a conductive rGO-NF substrate, the hierarchical 3D ZFO@NMO NSAs tend to have superb electronic conductivity, tailoribility, effective nanoporous channels, and appropriate roadways for rapid ion/electron transfer, which are required for rapid reversible redox reactions, thus reflecting the excellent electrochemical features, including the excellent specific capacitance, good rate performance, and prolonged cyclic performance of the three electrode assemblies for SCs. An asymmetric supercapacitor (ASC) device composed of ZFO@NMO NSAs@rGO-NF as the cathode and MOF-derived hollow porous carbon (MDHPC) as the anode exhibits a high energy density of 58.6 Wh kg-1 at a power density of 799 W kg-1 with prolonged cyclic durability (89.6 % after 7000 cycles), thus indicating its potential applicability towards advanced hybrid SCs.

Highly hydrophilic electrodeposited NiS/Ni3S2 interlaced nanosheets with surface-enriched Ni3+ sites as binder-free flexible cathodes for high-rate hybrid supercapacitors

In this study, nanostructured nickel sulfides (NiS, Ni3S2 and NiS/Ni3S2) were fabricated directly on the surface of flexible carbon fiber cloths by simply modifying the deposition parameters of pulse-reversal (PR) electrodeposition method and utilized as binder-free flexible electrodes for aqueous hybrid supercapacitors (SCs). X-ray photoelectron spectroscopy and contact angle measurement studies verifies that the surface of heterostructure NiS/Ni3S2 electrode has enriched Ni3+ sites and highly hydrophilic nature. Consequently, the heterostructure NiS/Ni3S2 electrode demonstrated superior rate capability than that of both single phase NiS and Ni3S2 electrodes. Additionally, the hybrid SC device based on the flexible NiS/Ni3S2 electrode delivered a capacity of 40.4 mAh g−1 at a current density of 2 A g−1 and representing a maximum energy density of 32.3 Wh kg−1 at an impressive power density of 1.6 kW kg−1. Furthermore, the device provided excellent electrochemical stability with a capacity retention of 86.2%, even after a 120-h floating test. Hence, the heterostructure NiS/Ni3S2 with interlaced nanosheets morphology should be considered as promising binder-free flexible electrode materials for next-generation energy storage applications.

One-step hydrothermal growth of reduced graphene oxide/nickel hexacyanoferrate nanocomposite on Ni foam for binder-free supercapacitor electrode

The in-situ growth of nickel hexacyanoferrate/reduced graphene oxide nanocomposite (Ni-HCF/rGO) on Ni foam was successfully achieved with a facile one-step hydrothermal method. Ni foam was not only used as the current collector but also the nickel source. By simply heating Ni foam in the aqueous solution containing graphene oxide (GO), potassium ferricyanide and P-toluenesulfonic acid (TSA), Ni-HCF/rGO nanocube arrays were synthesized on Ni foam. X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron miscroscopy (SEM) and Raman spectroscopy were used to characterize the Ni-HCF/rGO. As the supercapacitor electrode, Ni-HCF/rGO/Ni foam exhibits high capacity, long cycling life and good rate capability in 2.0 M KOH aqueous solution. An asymmetrical supercapacitor device (ASC) was assembled with Ni-HCF/rGO/Ni foam and activated carbon (AC) as the positive and negative electrodes, respectively. The fabricated ASC presents a maximum energy density of 4.38 W h m−2 at power density of 34 W m−2, suggesting its potential in practical applications.

ZnO Nano-Flowers Assembled on Carbon Fiber Textile for High-Performance Supercapacitor’s Electrode

Herein, a crystalline nano-flowers structured zinc oxide (ZnO) was directly grown on carbon fiber textile (CFT) substrate via a simple hydrothermal process and fabricated with a binder-free electrode (denoted as ZnO@CFT) for supercapacitor (SC) utilization. The ZnO@CFT electrode revealed a 201 F·g−1 specific capacitance at 1 A·g−1 with admirable stability of >90% maintained after 3000 cycles at 10 A·g−1. These impressive findings are responsible for the exceedingly open channels for well-organized and efficient diffusion of effective electrolytic conduction via ZnO and CFT. Consequently, accurate and consistent structural and morphological manufacturing engineering is well regarded when increasing electrode materials’ effective surface area and intrinsic electrical conduction capability. The crystalline structure of ZnO nano-flowers could pave the way for low-cost supercapacitors.

In-situ evolution of the NiO nanosheets on 3D-Ni-foam as a self-supported electrode for energy storage device applications

This report shows the inexpensive synthesis of in-situ evolution of NiO nanosheets on 3D-Ni-foam as an outstanding binder-free and self-supported electrode for supercapacitors. The NiO//NiO supercapacitor shows a high specific capacitance (159.3F g−1) at 6.7 A g−1, energy density (22.1 W h kg−1), and excellent power density (15250 W kg−1). It unfolds superb stability (93.9%) after 10,000 GCD cycles and (95.4%) after 14 h voltage holding tests (VHTs). Also, it shows a low leakage current of 0.09 mA during 2 h VHTs.

A new hierarchically porous Cu-MOF composited with rGO as an efficient hybrid supercapacitor electrode material

Exploring new materials for efficient energy storage is imperative to derive uninterrupted energy supply from non-conventional sustainable sources. The present paper reports on the synthesis of a new Cu-MOF (HMRL-1), involving the reaction of a tetracarboxylic linker and Cu2+ salt under solvothermal conditions. Using a simple ultrasonication approach, the as-synthesized MOF has been further used to fabricate a composite with reduced graphene oxide (rGO) (R). The resulting composite (HMRL-1/R) has been explored as a binder-free supercapacitor electrode material for deriving enhanced charge storage capacity. The supercapacitor performance of the composite material has been investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The electrochemical investigations reveal that HMRL-1/R composite exhibits hybrid capacitive features with a specific capacitance (CS) of 366.6 Fg−1 at 1 Ag−1 and excellent cyclic stability and performance retention, which is much higher than that of pristine HMRL-1 and R due to their synergistic effect. All the findings suggest that as-prepared material is a promising candidate for an electrode material in supercapacitor applications.

Co-electrophoretic deposition of Mn2O3/activated carbon on CuO nanowire array growth on copper foam as a binder-free electrode for high-performance supercapacitors

Co-electrophoretic deposition of Mn2O3/activated carbon on CuO nanowire array growth on copper foam as a binder-free electrode for high-performance supercapacitors

Flexible and porous Co3O4-carbon nanofibers as binder-free electrodes for supercapacitors

Flexible and porous Co3O4-carbon nanofibers as binder-free electrodes for supercapacitors

MnMoO4 nanorods-encapsulated carbon nanofibers hybrid mat as binder-free electrode for flexible asymmetric supercapacitors

In this work, the in-situ formation of MnMoO4 nanoparticles and simultaneous encapsulation within the porous carbon nanofiber (CNF) matrix through electrospinning-carbonization-thermal annealing processes were carried out. The results of various spectroscopic and morphological analyses confirmed the successful formation of rectangular-shaped MnMoO4 nanorods within the CNF matrix. The MnMoO4@CNF hybrid yielded a maximum specific capacitance of 389.7 F/g at 0.1 A/g, which is 3-folds more than that of CNF (123.4 F/g). The MnMoO4@CNF symmetric cell with an aqueous KOH electrolyte possessed a maximum energy density of 54.12 Wh/kg at a power density of 10 W/kg. The excellent capacitive performances of as-prepared MnMoO4@CNF nanofibers could be ascribed to their high specific surface area (229.35 m2/g) with wide mesoporous distribution (3–13 nm) and enhanced reactivity of the nano-sized MnMoO4 nanoparticles. The hybrid electrode demonstrated excellent cyclic stability with capacitance retention of 92.1% after 5000 cycles, suggesting restricted extrication of metal oxide from the CNF matrix during the charge-discharge process. A flexible solid-state asymmetric supercapacitor was assembled by using MnMoO4@CNF hybrid mat as a positive electrode and activated carbon cloth as a negative electrode. The polymer gel electrolyte (PVA + KOH) was used as electrolyte-cum-separator. The as-prepared MnMoO4@CNF//AC cell yielded a highest energy density of 37.46 Wh/kg and an equivalent power density of 278 W/kg. The present investigation could open new horizons in developing next-generation flexible solid-state supercapacitors for wearable electronics.

Capillary enhanced hydrophilic block carbon material for binder-free supercapacitor electrode

Excellent wettability of electrode materials is an important prerequisite for high-efficiency energy storage devices. Inspired by the capillarity, we design a new type of block carbon material with vertical channel array that can generate capillary tension and then enhance the hydrophilicity in aqueous liquid. When applied to supercapacitors, this electrode not only exhibits an excellent affinity ( e.g., 0°) for aqueous electrolyte, but also can be directly utilized as an electrode without any additions. Electrochemical measurements demonstrate that this novel hydrophilic and binder-free electrode enjoys satisfactory performances including high capacitance ( e.g., 2452 mF cm −2 at 5 mA cm −2 ), long cycling life in coin-type device ( e.g., 100% after 10 000 cycles). Furthermore, the pure carbon-assembled quasi-solid-state supercapacitor could deliver an appealing energy density up to 5.49 mWh cm −2 at a power density of 50.0 mW cm −2 . This work presents the strategy of hydrophilic conversion of materials through rational structural construction for the first time, and demonstrates an ultra-facile supercapacitor electrode which is full of practical application value. • Block carbon material with vertical channels was designed. • Capillary effect caused by channels optimized the transport of electrolyte. • The electrode exhibited better electrochemical performance in supercapacitors.

Template assisted synthesis of porous termite nest-like manganese cobalt phosphide as binder-free electrode for supercapacitors

The development of metal-organic frameworks (MOFs) opens up a new pathway of original or sacrificial template for synthesizing unique morphologies to serve as novel supercapacitor electrode materials. Herein, we describe a synthesis of termite nest-like nanostructured manganese cobalt phosphide on carbon fiber cloth (MCP/CC) by simple wet chemical method and followed by phosphorization. The fabricated MOF-derived binder-free MCP/CC electrode unveils a maximum areal capacitance (Ca) of 338 mF cm−2 at a current density of 2 mA cm−2 in 6 M KOH electrolyte. Additionally, a hybrid supercapacitor (HSC) was assembled using MCP/CC as a positive electrode and N, O, S enriched activated carbon coated CC (AC@CC) as a negative electrode, which delivered a maximum specific capacitance of 48 F g−1 at a wide potential window of 0–1.7 V. Moreover, HSC showed an excellent specific energy and power of 19.18 Wh kg−1 and 9996 W kg−1 with superior capacitance retention (94%) even after 10,000 cycles. Further, the device exhibited negligible self-discharge and have good stability even after 50 h of charge holding test. These results indicate that the MCP/CC nanostructure is a favorable electrode material for highly efficient energy storage applications.

Rational design of ZIF-8 assimilated hierarchical porous carbon nanofibers as binder-free electrodes for supercapacitors

Recently, tremendous attention has been paid to carbon-based fibers, particularly porous carbon fibers (PCFs), because of their great potential as electrodes for advanced supercapacitors (SCs). However, the relatively complex preparation and monotonous pore structure are still the most important challenge that PCFs needs to counter. In this work, an eco-friendly yet facile approach has been applied to synthesis PCFs with tunable multi-level pores and satisfactory electrochemical performance. By using the combinations of electrospinning technology, hard-template method and carbonization process, nanofibers with interconnected multi-level pores can be achieved. It is demonstrated that the pore engineered PCF possesses enhanced electrochemical performance. For instance, the PCF electrode possesses a high capacitance of 211 F g−1 in 6 mol L−1 KOH at a density of 0.5 A g−1 together with excellent rate capability. Meanwhile, a high areal capacitance of 1.2 F cm−2 also can be achieved at a mass loading of 10 mg cm−2. Additionally, symmetrical supercapacitor assembled by PCF electrodes exhibits good capacitance of 101.9 F g−1 at the current density of 0.5 A g−1, such device also can deliver an energy density up to 60.1 Wh kg−1 with ionic liquid electrolyte.

3D nanostructured CuxO modified copper foam as a binder-free electrode for all-solid-state supercapacitor

Copper oxides (CuxO) play an active role in the field of binder-free electrodes for supercapacitors due to their own advantages, including high theoretical capacity, non-toxicity, low cost, etc. Developing mild and cheap process to prepare CuxO nanomaterials would broad its application in supercapacitors. In this paper, copper oxide is used as an active material and copper foam (CF) is chosen as a substrate to synthesize metal oxide-based electrodes by an in-situ oxidation method. Ingeniously, the availability of copper foam has a dual nature encompassing as a collector as well as a copper source. The as-obtained CuxO/CF-60 electrode possesses an area capacitance of 354.6 mF cm−2 under 2 mA cm−2. It also has superior cycle stability with 93.8 % of initial capacitance undergo 5000 charge-discharge cycles. Moreover, the all-solid-state asymmetric supercapacitor, combining CuxO/CF-60 and activated carbon (AC) pasted on nickel foam (NF) as the respective positive and negative electrodes, exhibits an energy density of 25 μWh cm−2 when power density reaches 3 mW cm−2. The CuxO/CF-60//AC/NF device displays better cycling stability as 80.2 % of initial capacitance after 5000 cycles. This work provides a simple way for designing CuxO based electrodes and lays the foundation for subsequent improvements in electrochemical performance.

Rationally designed Mn2O3/CuxO core–shell heterostructure generated on copper foam as binder-free electrode for flexible asymmetric supercapacitor

Inherent poor conductivity and agglomeration of CuxO phase limit its further development in supercapacitors. High theoretical capacitance of Mn2O3 and the construction of core–shell heterostructure may provide a new strategy to solve these problems. Herein, the unique core–shell heterostructure of Mn2O3 nanosheets attached to CuxO nanowires is formed on copper foam (CF). This electrode material is prepared via an in-situ oxidation reaction followed by the combination of calcination and hydrothermal method. The areal capacitance of the as-obtained Mn2O3/CuxO/CF electrode at hydrothermal time of 9 h is 1403.5 mF cm−2 (779.7F g−1) at current density of 2 mA cm−2 (1 A g−1), which is much greater than that of other electrodes. It also exhibits a good stability with 92.8% retention of initial capacitance after 10,000 cycles. Besides, the flexible asymmetric supercapacitor (FASC) device is assembled by Mn2O3/CuxO/CF-9 and activated carbon (AC) coated on nickel foam (NF) as respective positive and negative electrodes. It can deliver specific capacitance of 512.7 mF cm−2 at 2 mA cm−2, and reaches 120.2 μWh cm−2 at a power density of 1.3 mW cm−2. The outstanding electrochemical characteristics may be ascribed to the unique core–shell heterostructure, making it potential application in the field of flexible supercapacitors.

Petal-like CoMoO4 Clusters Grown on Carbon Cloth as a Binder-Free Electrode for Supercapacitor Application.

The development of supercapacitors with a high energy density and power density is of great importance for the promotion of energy storage technology. In this study, we designed and prepared petal-like CoMoO4 clusters combined with carbon cloth as an excellent self-standing and binder-free electrode for asymmetric supercapacitors. Due to the abundant electrochemical active sites, the promising electron conduction, and ion diffusion rate, the CoMoO4@carbon cloth (CoMoO4@CC) electrode exhibits an excellent electrochemical performance. The results show that the CoMoO4@CC material exhibits a high specific capacitance (664 F/g at a current density of 1 A/g) and an excellent cycle stability (capacitance remains at 84.0% after 1000 cycles). The assembled symmetrical supercapacitor has an energy density of 27 Wh/kg when the power density is 600 W/kg. Even at a higher power density (6022 W/kg), it still maintains a good energy density (18.4 Wh/kg).