High-performance Pseudocapacitor Electrodes Research Articles

High-performance cabbage-like FeNi3/CoP2@C electrode with 3D porous structure for supercapacitors

The development of supercapacitors relies heavily on the design and manufacture of innovative electrode materials. FeNi3 alloy-based electrodes show good chemical stability and corrosion resistance as positive electrodes. However, their high internal resistance and low electronic conductivity limit the large-scale application. In this work, the CoP2 particles with high electrical conductivity is integrated with FeNi3 nanoalloys to construct FeNi3/CoP2 heterostructure loaded on biomass-derived cabbage-like porous carbon. Combined with the experimental result and density functional theory, the introduction of CoP2 nanoparticles greatly improves the electrochemical properties of the prepared FeNi3/CoP2@C composite. By adjusting the annealing temperature, the FeNi3/CoP2@C-800 electrode displays a specific capacitance of 1135.5 C g−1 at 1 A g−1 with a surface area of 259.45 m2 g−1. In addition, the assembled FeNi3/CoP2@C-800//AC (activated carbon) asymmetric supercapacitor provides a high energy density of 52.2 Wh kg−1 at 525.0 W kg−1 and good electrochemical cycling stability with a capacitance retention rate of 84.23 % after 10,000 cycles. The study offers a feasible idea for making high-performance pseudocapacitive electrode material.

Binder-free NiO/CuO hybrid structure via ULPING (Ultra-short Laser Pulse for In-situ Nanostructure Generation) technique for supercapacitor electrode

Developing a cost-effective pseudocapacitor electrode manufacturing process incorporating binder-free, green synthesis methods and single-step fabrication is crucial in advancing supercapacitor research. This study aims to address this pressing issue and contribute to the ongoing efforts in the field by introducing ULPING (Ultra-short Laser Pulse for In-situ Nanostructure Generation) technique for effective design. Laser irradiation was conducted in ambient conditions to form a CuO/NiO hybrid structure providing a synergistic contribution to the electrical behavior of the electrode. Mainly, the effects of surface morphology and electrochemical surface because of tuning laser intensity were analyzed. The samples demonstrated high oxide formation, fiber generation, excellent porosity, and ease of ion accessibility. Owing to a less than 10-min binder-free fabrication method, the electrochemical performance of the as-fabricated electrode was 25.8 mC cm−2 at a current density of 1 mA cm−2 proved to be excellent. These excellent surface properties were possible by the simple working principle of pulsed laser irradiation in ambient conditions and smart tuning of the important laser parameters. The CuO/NiO electrode demonstrates excellent conductivity and rewarding cyclic stability of 83.33% after 8000 cycles. This study demonstrates the potential of the ULPING technique as a green and simple method for fabricating high-performance pseudocapacitor electrodes.

Fabrication of 3D microporous Ni foam for growing CoMoO4 nanosheet arrays as high-performance pseudocapacitive electrode

A 3D porous Ni foam with pore size in the range of several micrometers can accommodate more CoMoO 4 nanosheet arrays in a limited area with merit of high-efficient electron/ion transportation, thus leading to a high areal performance as pseudocapacitive electrode. • A novel 3D porous Ni foam current collector is fabricated by a scale-up method. • The interconnected pores can be controlled to accommodate electroactive materials with different mass loading values. • The 3DNF@CMO enables a shortened and homogeneous electron/ion transfer pathway. A 3D porous Ni foam (3DNF) with pore and ligament size in the ranging of several micrometers is fabricated via a method of combining nonsolvent induced phase separation (NIPs) and solid-state sintering. Benefiting from the interconnected pores, the pseudocapacitive CoMoO 4 nanosheet arrays can grow on the unique 3DNF (3DNF@CMO) with loading mass of 3.2 mg cm −2 . The 3DNF can act as a connection between internal and external circuit, ensuring rapid and stable electron/ion transfer. Because of these merits, the 3DNF@CMO-8 electrode shows a high area capacitance of 1.53F cm −2 at 3 mA cm −2 and long lifespans surpassing 8000 cycles. These results highlight the importance of rational design of 3D current collectors and reveal a promise for developing idea electrodes for energy storage systems.

Engineering oxygen-deficient nanocomposite comprising LaNiO3-δ and reduced graphene oxide for high-performance pseudocapacitors

Aiming at a high performance pseudocapacitive electrode - an oxygen-deficient nanocomposite comprising reduced graphene oxide-Lanthanum nickelate LaNiO3 (rGO-LNO) was synthesized using a facile binder-free approach. The structural identity and the phase purity of the nanocomposite were verified by X-ray diffraction and electron microscopy studies coupled by the inputs from Raman scattering. The assistance of rGO in the amplification of oxygen vacancies in rGO-LNO relative to LNO was confirmed from X-ray photoelectron spectroscopy (XPS). Maximum specific capacitance of 920 F g−1 at 1 A g−1 current density in 6 M KOH solution in a three-electrode set up was observed. An excellent long-term cycling efficiency of over 99 % even at a high current density of 10 A g−1 in solid-state-symmetrical setup. Analysis of self-discharge and leakage current parameters concluded sturdy electrode dynamics. Deconvolutions of cyclic voltammograms were suggestive of majorly bulk conduction over diffusive kinetics. In summary, LNO facilitates a faster electron transfer rate and while rGO allows the penetration of the electrolytes into the bulk matrix, and allows more effective utilization of the electrode materials via. an efficient ion-exchange.

Cubic like CoMn2O4 nanostructures as advanced high-performance pseudocapacitive electrode

In this work, a synthesis of cubic-like CoMn2O4 uniform nanostructures with KOH-NaOH involved in the hydrothermal method has been reported. The crystal structure phase purity, functional groups, and morphology of the CoMn2O4 have been investigated by X‑ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-reso­lution transmission electron microscopy (HR-TEM) analyses. The electrochemical behaviour of CoMn2O4 electroactive material has been examined for supercapacitors. The electrode displays excellent capacitive behaviour with superior electrochemical properties. The cubic-like morphology structure with enough free space is beneficial for improving electrochemical performance. The CoMn2O4 electrode exhibits a faradaic capacitance with the highest specific capacitance value of 762.4 F g-1 at a scan rate of 5 mV s-1. The coulombic efficiency of the CoMn2O4 electrode was found to be 91.2 % after 2000 charging-discharging cycles. The nanostructures of CoMn2O4 make a prominent contribution to the excellent electrochemical performance of the prepared electrode.

Ultra-small RuO2 nanoparticles supported on carbon cloth as a high-performance pseudocapacitive electrode

Ultra-small RuO2 nanoparticles supported on carbon cloth as a high-performance pseudocapacitive electrode

NiO nanoparticles/graphene nanocomposite as high-performance pseudocapacitor electrodes: Design and implementation

A simple hydrothermal approach was used to successfully fabricate NiO/G nanocomposites. Since the addition of nickel oxide nanoparticles (NiO) to graphene instead of conducting polymeric materials produces better capacitances and improved capacity retention. Graphene-based inorganic composites have been attracting more and more attention. The as prepared NiO/G nanocomposite is characterized by XRD, TEM, Raman, XPS and nitrogen adsorption/desorption. It is demonstrated that NiO nanoparticles adorn graphene sheets to generate hierarchical nanostructures with rich porosity (33.8 nm) and substantial specific surface area (51 m2 g−1). Electrochemical characterization demonstrate that the mesoporous graphene/NiO can deliver a specific capacitance of 632 F g−1 at a current density of 2 Ag−1 and have a capacitance retention of 99.7% at 2Ag−1 after 6000 continuous charge–discharge cycles. In addition, the ASC constructed from NiO/G shows excellent energy density (30.56 Whkg−1), excellent power density (2800 Wkg−1) and impressive cycle performance (capacitance retention after 6000 cycles is approximately 92.7%). This strategy aids in the fabrication and utilization of hybrid nanocomposite in high-geared reversible supercapacitors.

Highly ordered nanoscale phosphomolybdate-grafted polyaniline/metal hybrid layered structures prepared via secondary sputtering phenomenon as high-performance pseudocapacitor electrodes

The development of energy storage electrode materials is important for enhancing the electrochemical performance of supercapacitors. Despite extensive research on improving electrochemical performance with polymer-based materials, electrode materials with micro/nanostructures are needed for fast and efficient ion and electron transfer. In this work, highly ordered phosphomolybdate (PMoO)-grafted polyaniline (PMoO-PAI) deposited onto Au hole-cylinder nanopillar arrays is developed for high-performance pseudocapacitors. The three-dimensional nanostructured arrays are easily fabricated by secondary sputtering lithography, which has recently gained attention and features a high resolution of 10 nm, a high aspect ratio greater than 20, excellent uniformity/accuracy/precision, and compatibility with large area substrates. These 10 nm scale Au nanostructures with a high aspect ratio of ∼30 on Au substrates facilitate efficient ion and electron transfer. The resultant PMoO-PAI electrode exhibits outstanding electrochemical performance, including a high specific capacitance of 114 mF cm−2, a high-rate capability of 88%, and excellent long-term stability.

Tween modified CuFe2O4 nanoparticles with enhanced supercapacitor performance

Binary metal oxides CuFe2O4 can be a low-cost and high-performance pseudo-capacitive electrode material. However, their large size distributions and low dispersion caused by agglomeration can not exert their potential capacity. Hence, we used tween to modify CuFe2O4 (CuFe2O4-T) nanoparticles via a facile hydrothermal method. The composite nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis reflectance spectroscopy, and Fourier transform infrared spectroscopy. After modification, CuFe2O4-T showed high purity, greatly reduced particle size with the diameter about 10–20 nm, and decreased bandgap energy. When serving as supercapacitor electrodes, their electrochemical behaviors were examined by cyclic voltammetry, galvanostatic charge-discharge study, and electrochemical impedance spectroscopy. CuFe2O4-T exhibited improved supercapacitor behavior, with a specific capacitance of 437.3 F g−1 at the scan rate of 0.004 Vs−1 in 0.5 M H2SO4 electrolyte, 88.6% capacitance stability retention over 2000 cycles. An asymmetric supercapacitor device was assembled by using CuFe2O4-T as a positive electrode, which showed good capacitive behavior and cyclic stability. This work indicates that tween can effectively improve the performance of CuFe2O4 nanoparticles, and CuFe2O4-T will have great promise for wide electrochemical application.

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.

A high-performance pseudocapacitive electrode based on CuO–MnO2 composite in redox-mediated electrolyte

In the present work, a simple and cost-effective precipitation approach was carried out to fabricate CuO nano-needle, and its electrochemical performance was evaluated in a redox-mediated electrolyte (2 M KOH and 0.3 M K3Fe(CN)6). A high specific capacitance of 2519 F/g was recorded at a specific current of 8 A/g. However, the electrode suffered from poor rate capability as the specific capacitance was rapidly decreased to 100 and 1 F/g when the specific current was increased to 30 and 50 A/g, respectively. The CuO nanoparticles were further modified with MnO2 by a hydrothermal method, and the resulting CuO–MnO2 (CMO6) electrode delivered a high specific capacitance of 539 F/g even at very high specific current of 50 A/g. The as-synthesized electrode materials were structurally and morphologically characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the CuO and MnO2–CuO composites have been examined in detail. Synopsis Modification of pristine CuO nano-needles with MnO2 nanosheets improved the electrochemical performance of the material. The composite was able to deliver a high specific capacitance of 539 F/g even at very high specific current of 50 A/g.

Construction of mesoporous carbon microsphere/polyaniline composites as high performance pseudocapacitive electrodes

Mesoporous carbon microspheres (MCMs), as a supercapacitor electrode material, have good gravimetric capacitance and rate performance; however, their low volumetric capacitance, which results from their low density, restricts their application as a micro power source. Herein, polyaniline was introduced into the channels of MCMs to achieve a synergistic effect and significantly increase the volumetric capacitance. MCMs with a high surface area and pore volume allowed the uniform dispersion of PANI within their channels in nanoscale dimensions. The interconnected carbon framework could provide excellent electrical conductivity and alleviate the structural collapse of PANI. Moreover, PANI could function not only as an active pseudocapacitive material that facilitated energy storage but also as a proton transport media that promoted a rapid protonation/deprotonation process during the redox reaction in the internal channels. As a result, PANI/MCM composites, even with a poor pore structure, delivered a high volumetric capacitance of 539F cm−3 at 1 A g−1 and an excellent rate performance of 83% at current densities ranging from 0.5 to 20 A g−1. In addition, PANI/MCM composites exhibited good cycling stability, retaining 84% of the capacitance after 1000 charge/discharge cycles at 1 A g−1, owing to the high mechanical strength of the MCMs. Therefore, this synthesis strategy could provide an efficient and scalable solution for the development of supercapacitor electrode materials.

Recent advances in metal oxide/hydroxide on three-dimensional nickel foam substrate for high performance pseudocapacitive electrodes

Abstract The high demand for long-lasting and portable energy storage devices with enhanced energy and power densities has attracted researcher's interest globally. The three-dimensional (3D) nickel foam is a promising electrode material for storing energy in various devices because they possess large surface area, are very conductive and enjoy a continuous permeable 3D system. This article provides a review and detailed information on the uses of 3D nickel foam-based electrodes with metal oxides/hydroxides of different morphologies for high-performance pseudocapacitors. We assess the limitations and future prospects of 3D nickel foam-based electrodes with metal oxides/hydroxides for industrial application towards enhancing pseudocapacitors' energy storage capability.

High-performance pseudocapacitor electrodes based on the flower-like nickel sulfide coated carbon nanofiber webs

Flower-shaped Ni3S2/Ni structures were synthesized on the surface of three-dimensional (3D) carbon fiber webs (CFWs) using electroless plating of Ni and subsequent sulfuration. The as-obtained product of this treatment was characterized using various techniques including scanning electron microscopy and X-ray diffraction, and was confirmed to indeed be Ni3S2/Ni-coated CFWs. Moreover, these webs were observed to have a unique architecture, consisting of a hierarchical porous structure with the flower-shaped morphology. This structure apparently enabled efficient ion diffusion and rapid electron transfer through the 3D CFW supports, as the Ni3S2/Ni-coated CFWs showed excellent electrochemical performances: a high areal capacitance of 240 mF/cm2 at current density of 1 mA/cm2, a high rate capability of 85.4% retention at current density of 15 mA/cm2, and good long-term stability (98% over 2000 cycles).

Polyaniline nanotube synthesized from natural tubular halloysite template as high performance pseudocapacitive electrode

Design and preparation of nanostructured conducting polymers (CPs) is a very important research direction for high performance CPs-based supercapacitors (SCs). With hollow structure, high surface area, tunable surface properties and abundant resources, natural halloysite is a promising template agent for preparing new nanotubular-structure CPs. Here, nanotubular-structure polyaniline was successfully synthesized using natural tubular halloysite as hard template. The obtained tubular polyaniline presents high specific capacitance at various current density as electrode material for supercapacitors. After a facile carbon coating, the carbon coated tubular polyaniline shows high specific capacitance of 654 F g−1 at the current density of 1 A g−1 and excellent electrochemical stability with capacitance retentions ∼87% after 10000 cycles. This work may prove the feasibility of preparing high performance CPs-based nanostructure electrode materials for SCs application based on inexpensive natural clay minerals.

NiCo2O4-based nanostructured composites for high-performance pseudocapacitor electrodes

Nanostructured electrodes for supercapacitors made by combination of electrical double layer and pseudocapacitive based-nanomaterials within a single hybrid composite has a great potential on expanding the range of use of these devices and increase their electrochemical performance. In this work, we developed several nanostructured composites with combinations of such types of materials with potential applicability as electrodes in supercapacitors. In particular, these composites were obtained by easy, cost-effective and scalable procedures, and were composed by NiCo2O4 cores as the main reversible fast faradaic-based nanomaterial and either the conductive polymer polyaniline (PANI), multiwall carbon nanotubes (MWCNTs), or reduced graphene oxide (r-GO) as the electrical double layer-based carbonaceous-based nanomaterials in order to enable the combination of both type of energy storage processes within a single nanostructured electrode. These constructions allowed us to obtain specific capacitance as large as 1760 F/g, 900 F/g and 734 F/g at a current density of 1 A/g for NiCo2O4/PANI, NiCo2O4/MWCNT, and NiCo2O4/r-GO nanostructured composite electrodes, respectively. Besides, the stability of NiCo2O4/MWCNTs and NiCo2O4/r-GO-based electrodes was outstanding, with capacity losses below 10% after the periods of operation (>1000 cycles).

Core-shell structured Ni6MnO8@carbon nanotube hybrid as high-performance pseudocapacitive electrode material

Binary metal oxides have been proved to possess better pseudocapacitive performance than single metal oxide analogies. Substitution of toxic and high-cost ions (Co and Mo) in binary metal oxides with low-cost and environmentally-friendly ions (Ni and Mn) is of great economic and environmental importance. In this paper, murdochite-type binary metal oxides (i.e., Ni6MnO8) and binary metal oxides@carbon nanotubes (i.e., Ni6MnO8@CNTs) core-shell structure were synthesized via a facile hydrothermal approach followed by a calcination process. Electrochemical measurement results indicated that the synthesized Ni6MnO8@CNT core-shell structure showed a high specific capacitance of 1213 F g−1 at 1 A g−1 with two times capacitance value of Ni6MnO8 at same current density. Even at the high current density of 20 A g−1, the Ni6MnO8@CNT core-shell structure can still deliver a high capacitance value of 711 F g−1, which value is also much higher than that of Ni6MnO8 at the current density of 1 A g−1. With the prepared Ni6MnO8@CNT hybrid as positive electrode and activated-polyaniline-derived-carbon as negative electrode, an asymmetric supercapacitor cell (ASC) was successfully assembled. The assembled ASC device exhibited excellent pseudocapacitive performance with a high specific capacitance of 154 F g−1 at 1 A g−1 and a high energy density of 58.2 Wh kg−1 at a power density of 831.4 W kg−1. Even at a high power density of 16.6 kW kg−1, the ASC device can still deliver a high energy density of 23.1 Wh kg−1, suggesting the promising applications of Ni6MnO8@CNT hybrid in supercapacitors.

Yeast-derived N-doped carbon microsphere/polyaniline composites as high performance pseudocapacitive electrodes

Carbonaceous materials derived from a variety of cheap and sustainable biomass have shown great potential as conductive substrates for the coating of pseudocapacitive materials. In this study, yeast-derived N-doped carbon microsphere/polyaniline (YC/PANI) composites are synthesized by an in situ polymerization approach, using yeasts as the carbon source and structural template. The self-templated hollow YC with good conductivity has many active sites for anchoring PANI, and alleviates the structure destruction caused by the redox reaction of PANI. Accordingly, the YC/polyaniline composite as a supercapacitor electrode exhibits a high specific capacitance (500 F g−1 at a current density of 1 A g−1) and good rate capability in a three-electrode system. Additionally, the symmetric supercapacitor of the YC/polyaniline composite delivers a high capacitance (100 F g−1 at 1 A g−1) and remarkable cycle life (95.4% of the initial capacitance maintenance after 5000 cycles). The uniform coating of PANI nanowires and robust structure stability of composites are responsible for excellent electrochemical properties.

A high-performance pseudocapacitive electrode material for supercapacitors based on the unique NiMoO4/NiO nanoflowers

Currently, although some progress has already been achieved, the complex and high-cost synthetic route, and low electrochemical properties of supercapacitor still restrict its practical application. Here, NiMoO4/NiO nanoflowers material with a high specific surface area grown on a nickel foam conductive substrate is successfully synthesized via a facile and efficient method, which exhibits an excellent capacitance of 10.3 F cm−2 (1982.3 F g−1), a good rate capability, and a remarkable cycling stability (capacity remain 98.6% after 3000 cycles). In addition, a novel asymmetric supercapacitor with excellent energy density is also fabricated via the NiMoO4/NiO nanoflowers as the positive electrode and a piece of active carbon as the negative electrode in 3 M KOH electrolyte. The optimized asymmetric device operating at 1.7 V also offers a high energy density and an outstanding long-term cycling stability. These impressive results suggest that such NiMoO4/NiO nanoflowers can pave the way for designing and developing next-generation high-performance storage systems.

Construction of NiCo2O4@NiFe LDHs core/shell nanowires array on carbon cloth for flexible, high-performance pseudocapacitor electrodes

NiFe layered double hydroxides (LDHs), a class of ionic layered compounds with high electrochemical activity, possess great potential in the field of pseudocapacitive energy storage. However, the practical applications of NiFe LDHs in supercapacitors are largely hindered by their inherently poor cycling life and low electrical conductivity. In this work, NiFe LDHs electrodeposited on mesoporous and conductive NiCo2O4 nanowire arrays that are grown on flexible carbon cloth, are investigated as active materials for pseudocapacitive application. This rational core/shell electrode design promises high specific surface area, shorten electron and ion transport distance for the enhancement of electrochemical kinetics. As such, a high specific capacitance (1.9 F cm−2 at 1 A cm−2, and 1160 F g−1 at 1 A g−1), excellent rate capability (83% retention as the current density was increased from 1 A cm−2 to 20 A cm−2), decent cycling stability (79% retention after 1000 charging/discharging cycles), and good flexibility have been obtained, implying their potential application as energy storage devices for flexible electronics.