Supercapacitive properties of manganese nitride thin film electrodes prepared by reactive magnetron sputtering: Effect of different electrolytes

Development of metal nitride-based thin film binder-free electrodes is a rapidly emerging area of research for the development of supercapacitors. The manganese nitride (Mn₃N₂) binder-free thin film electrodes were prepared using DC magnetron sputtering process. X-ray diffraction and the Raman spectroscopy characterization confirmed the formation of the tetragonal phase of Mn₃N₂ thin film. Field emission scanning electron microscopy revealed that the Mn₃N₂ particles are in nanoscale range and the particles with pyramidal shape are distributed uniformly on the surface of the film. Further, the Mn₃N₂ electrodes were examined by cyclic voltammetry and galvanostatic charge-discharge measurements to investigate the supercapacitive properties. The electrochemical measurements were performed on Mn₃N₂ deposited on conducting stainless steel substrates in different electrolytes (KOH, KCl and, Na₂SO₄ at 1 M concentration). The effect of various electrolytes on the areal capacitance, cycling stability, capacitance retention of the Mn₃N₂ electrodes was investigated. The Mn₃N₂ electrodes show high areal capacitance of 118 mF cm⁻² for KOH, 68 mF cm⁻² for KCl and 27 mF cm⁻² for Na₂SO₄ at a scan rate of 10 mV/s. Moreover, the Mn₃N₂ electrodes indicated excellent cycling stability with capacitance retention of 98.5%, 89% and 83% for KOH, KCl, and Na₂SO₄, electrolytes respectively after 4,000 cycles. A comparative study on the electrochemical supercapacitive properties of the Mn₃N₂ electrode in different aqueous electrolytes is reported for the next generation electrochemical energy storage devices.     

Freestanding Co3N thin film for high performance supercapacitors

Suitable electrode materials play a decisive role in the performance of supercapacitors. In recent years, transition metal nitrides come into view because of their advantages of superior electrical conductivity exceeding the corresponding metal oxides and higher specific capacitance compared with carbon-based materials. Herein, we have successfully synthesized the binder-free Co₃N thin films for high-efficiency supercapacitor by reactive magnetron sputtering. Remarkedly, the Co₃N thin film electrodes can reach a high specific capacity of 47.5 mC cm^?2 at a current density of 1.0 mA cm^?2 along with reasonable cycling stability (78.1% remaining after 10,000 cycles). These findings have proved that the Co₃N thin films have great potential applications for supercapacitors or other electrochemical energy storage devices.     

Rational design of binder-free ZnCo2O4 and Fe2O3 decorated porous 3D Ni as high-performance electrodes for asymmetric supercapacitor

The development of hierarchical, porous film based current collector has created huge interest in the area of energy storage, sensor, and electrocatalysis due to its higher surface area, good electrical conductivity and increased electrode-electrolyte interface. Here, we report a novel method to prepare a hierarchically ramified nanostructured porous thin film as a current collector by dynamic hydrogen bubble template electro-deposition method. At a first time, we report a porous 3D-Ni decorated with ZnCo₂O₄ and Fe₂O₃ by simple, low-cost electrochemical deposition method. The fabricated porous 3D-Ni based electrodes showed an excellent electrochemical property such as high specific capacitance, excellent rate capability, and good cycle stability. The asymmetric solid-state supercapacitor device was fabricated using porous, 3D Ni decorated with ZnCo₂O₄ and Fe₂O₃ as the positive and negative electrodes. The fabricated ZnCo₂O₄//Fe₂O₃ asymmetric device delivered an areal capacitance of 92?mF?cm^?2 at a current density of 0.5?mA?cm^?2 with a maximum areal power density of 3?W?cm^?2 and areal energy density of 28.8?mWh?cm^?2. The higher performances of porous, 3D current collector have a huge potential in the development of high performance supercapacitor.     

A review on metal nitrides/oxynitrides as an emerging supercapacitor electrode beyond oxide

Electrode materials design is the most significant aspect in constructing a supercapacitor device. The evolution of metal nitrides/oxynitrides as supercapacitor electrode is strikingly noticeable today besides prevailing carbon or 2D materials, metal oxides/hydroxides and conducting polymers electrode materials. The theoretically estimated specific capacitance of a nitride-based supercapacitor is 1,560 F g^-1. These nanostructures exhibit an excellent capacitive behavior with a specific capacitance of 15–951.3 mF cm^-2 or 82–990 F g^-1, high energy density (16.5-162 Wh Kg^-1) and power density (7.3-54,000 W Kg^-1). On this account, supercapacitor performance of metal nitrides/oxynitrides is reviewed exclusively. The major focus of the present review is directed towards state-of-art progress in supercapacitor performance of nitrides/oxynitrides, underlying charge-storage mechanism, important outcomes and their limitations. Finally, we conclude with challenges and prospects of metal nitrides/oxynitrides for supercapacitor electrodes.     

Tailoring surface capacitance of Ti3C2Tx-PANI@CNTs nanoarchitecture for tunable energy storage and high-performance micro-supercapacitor

Transition metal carbide or nitride (MXenes), as a novel family of two-dimensional materials, exhibit huge potential for electrochemical energy storage thanks to their excellent electrical conductivity, fast ion diffusion rate, high electrochemical activity and good hydrophilicity. However, the electrochemical properties of MXenes tend to be deteriorated due to the self-restacking phenomenon. Herein, by self-assembly, a unique three-dimensional (3D) Ti₃C₂T_x-PANI@CNTs (TPCs) nanoarchitecture was constructed. Through optimizing structures, the surface capacitance of TPCs can be tailored to tune energy storage. The optimal specific capacitance up to 431.9 F/g was achieved under 1 A/g. Further, the TPCs nanoarchitectures were prepared into self-standing films with excellent mechanical properties and micro-supercapacitors (MSCs) in various shapes were manufactured based on the film. The MSCs demonstrate competitive energy storage capacities, obtaining an areal capacitance of 78.2 mF/cm² and energy density of up to 2.72 μWh/cm², still maintain excellent performance under harsh bending. The strategy for constructing 3D nanoarchitectures and further manufacturing MSCs can inspire the design of novel electrode materials and devices to advance the development in the field of energy storage.     

Corn Cob Lignin-based Porous Carbon Modified Reduced Graphene Oxide Film For Flexible Supercapacitor Electrode

Flexible supercapacitors (FSCs) have attracted widespread attention of many researchers as a type of portable energy storage devices. However, there are still challenges in preparing renewable and inexpensive electrode materials. Herein, we prepared the porous carbon (PC) by the two-step process involving hydrothermal method and low-temperature heat treatment using corn cob lignin as the carbon source, and different types for PC were obtained by changing the temperature of low temperature heat treatment (100?°C–300?°C). The flexible electrode film was prepared by combining the obtained corn cob lignin-based PC with reduced graphene oxide (RGO), in addition, we investigated the effect of PC obtained by different low-temperature heat treatment (100?°C, 150?°C, 200?°C, 250?°C, and 300?°C) on the electrochemical properties of the composite electrode. The optimal low-temperature heat treatment temperature (250?°C) was determined and the PC250/RGO film electrodes displayed a high area specific capacitance of 636 mF/cm² with a mass of 2.2?mg/cm² (specific capacitance of 289?F/g) at 0.2?mA/cm² and 82% of the capacitance was retained after 10,000 charge and discharge cycles at 5?mA/cm², at the same time on the electrode film flexibility test, the influence of different bending angle on the electrochemical properties can be ignored. The assembled supercapacitor had the advantages of flexible, lightweight, low price, and environment friendly, which can achieve area specific capacitance of 324.5 mF/cm² at 0.2?mA/cm² and 91.8% capacitance retention after 1000 charging/discharging cycles. These good electrochemical properties illustrate the application prospects of composite electrode materials in wearable and portable electronic devices.     

Evaluation of Graphene/WO<Subscript>3</Subscript> and Graphene/CeO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Structures as Electrodes for Supercapacitor Applications

The combination of graphene with transition metal oxides can result in very promising hybrid materials for use in energy storage applications thanks to its intriguing properties, i.e., highly tunable surface area, outstanding electrical conductivity, good chemical stability, and excellent mechanical behavior. In the present work, we evaluate the performance of graphene/metal oxide (WO₃ and CeO _x ) layered structures as potential electrodes in supercapacitor applications. Graphene layers were grown by chemical vapor deposition (CVD) on copper substrates. Single and layer-by-layer graphene stacks were fabricated combining graphene transfer techniques and metal oxides grown by magnetron sputtering. The electrochemical properties of the samples were analyzed and the results suggest an improvement in the performance of the device with the increase in the number of graphene layers. Furthermore, deposition of transition metal oxides within the stack of graphene layers further improves the areal capacitance of the device up to 4.55 mF/cm², for the case of a three-layer stack. Such high values are interpreted as a result of the copper oxide grown between the copper substrate and the graphene layer. The electrodes present good stability for the first 850 cycles before degradation.     

All polymer-based transparent composites for electrothermal actuator and supercapacitor

With the rapid development of smart devices, multifunctional integrated systems are greatly developed. Although several multifunctional devices integrated with functions of actuation, sensing, and energy storage have been successfully fabricated, most of these integrated multifunctional systems are opaque. Here, all polymer-based transparent composites are proposed for the electrothermal actuator, supercapacitor, and intelligent integrated electronic system. The transmittances of the polyaniline@poly(3, 4-ethylene dioxythiophene): poly(styrenesulfonate)/polyethylene terephthalate/polyethylene hierarchical composites with transmittance over 40% are prepared by the facile method of in-situ polymerization and “cut-paste” process, which can be directly used as transparent actuators as well as electrodes for transparent supercapacitors. The transparent actuator exhibits large bending deformation (>0.8 cm⁻¹) and long-term repeatability under electrical stimulation. Also, the transparent supercapacitor presents a high areal capacitance of 9.9 mF cm⁻² and excellent cycling stability. Due to the above advantages, a series of practical applications are designed, such as biomimetic transparent grippers, flexible supercapacitor arrays, and so forth. Finally, an intelligent integrated electronic system with intelligent electrical-controlled switches and supercapacitor arrays is successfully constructed to demonstrate the practical application of functional polymer film in smart devices.     

Effects of specific surface area of electrode and different electrolyte on capacitance properties in nano porous-structure CrN thin film electrode for supercapacitor

Thickness and specific surface area of the film electrode are critical parameters for supercapacitors. The relationship between the thickness and the specific surface area of the film directly affects the capacitance and electrochemical stability performance of super supercapacitors, which virtually affects the contact chance of ion in the electrolyte on the surface of electrode and the ion transport path of electrode. In this paper, the CrN thin films with a thickness of 200–3500 nm are prepared using direct current magnetron sputtering. Atomic force microscopy (AFM) technique is introduced to investigate the relationship between thickness and the specific surface area of the CrN films. The electrochemical performances of CrN electrode with the nanoporousper structure is analyzed in different electrolytes H₂SO₄, Na₂SO₄ and NaCl aquous solutions. The specific surface area of the film increases linearly with the film thickness increases. The areal capacitance is also linearly related to the specific surface area. The spurtted CrN film with a thickness of 3370 nm has a specific surface of up to 43.59 cm² per cm² footprint area. Its areal and volume capacitances reache to 53.92 mF cm^?2 and 650 F cm^?3 at 5 mV s^?1, respectively. In addition, the areal capacitance of CrN film electrode with 655 nm possesses reaches to 40.53 mF cm^?2 for 0.5 M H₂SO₄ solution, 32.69 mF cm^?2 for 0.5 M Na₂SO₄ solution and 9.17 mF cm^?2 for NaCl solution at a scan rate of 5 mV s^?1. Furthermore, the CrN film electrode exhibits excellent capacitance retention of 95.3%, 93.8% and 89.9% in H₂SO₄, Na₂SO₄ and NaCl electrolytes, respectively, after 2000 cycles. Therefore, the sputtered CrN thin film is an potential electrode material for electrochemical supercapacitors.     

Photoresist-derived porous carbon for on-chip micro-supercapacitors

Photoresist, which is frequently used in existing microelectronics processing, can be pyrolyzed to form a conductive carbon film. We demonstrate that a pyrolysis technique of SPR-220 photoresist, consisting of heating in Ar ambient to 900 °C followed by further annealing in an H₂/Ar mixture, results in a high surface area porous carbon, applicable to supercapacitor electrode fabrication. Electrochemical testing of the pyrolyzed photoresist film yields a specific areal capacitance of 1.5–3.5 mF/cm² and a specific volumetric capacitance of 15–35 F/cm³. These results are obtained on the as-pyrolyzed films, without additional activation or deposition of electroactive species. The cycling stability of the films is shown to be robust over 10,000 cycles. This photoresist pyrolysis process could be readily integrated into microelectromechanical systems or microelectronics technology for on-chip energy storage.     

Enhanced electrochemical performance of hybrid composite microstructure of CuCo2O4 microflowers-NiO nanosheets on 3D Ni foam as positive electrode for stable hybrid supercapacitors

Self-assembled composite porous structures comprising CuCo₂O₄ microflowers and NiO hexagonal nanosheets were synthesized on a conducting 3D Ni foam surface [CCO/NO] using a simple hydrothermal method. This unique composite assembly was further characterized and electrochemically evaluated as a binder-free positive electrode for hybrid supercapacitor application. The study showed that the CCO/NO exhibited a maximum areal capacitance of 1444 mF cm^?2, significantly higher than the parent CuCo₂O₄ and NiO electrodes, with remarkable stability of 88.5% for 10,000 galvanostatic charge-discharge cycles. Key features for the enhanced electrochemical performance of CCO/NO can be related to a lowered diffusion resistance because the hybrid nanocomposite porous assembly generates short diffusion paths for electrolyte ions and more active sites for reversible faradaic transition for charge storage. The hybrid supercapacitor was assembled using activated carbon as a negative electrode and CCO/NO as a positive electrode in alkaline electrolyte, performed at an improved potential of 1.6 V. Device showed a maximum areal capacitance of 122 mF cm^?2, a maximum areal energy density of 43 μWh cm^?2, and a maximum areal power density of 5.1 mW cm^?2. This hybrid supercapacitor showed remarkable cyclic stability up to 98% for 10,000 cycles. This study encourages the development of low-cost, high-performance, durable electrode designs using hybrid composite for next-generation energy storage systems.     

Binder-less fabrication,some surface studies,and enhanced electrochemical performance of Co,Cu-embedded MnO2 thin film electrodes for supercapacitor application

We report the fabrication of nanocystalline MnO₂ thin film-based electrode on a predeposited indium tin oxide (ITO) film on the glass substrate, using a binderless and simple two-electrode electrofabrication approach. Effects of Co and Cu incorporation on microstructural and electrochemical performance of the electrode were optimally and extensively investigated. The experimental results for the optimum fabrication conditions for Co@MnO₂ and Cu@MnO₂ and pure MnO₂ thin film-based electrode samples showed uniqueness in microstructural features, degrees of crystallinity and roughness, and high electrochemical energy storage performance. Co@MnO₂ film electrode exhibited remarkable specific capacitance (1068 Fg^-1) and areal capacity (25.78 mAh cm^?2) as against other electrode films (Cu@MnO₂ and pure MnO₂) which exhibited specific capacitances 837 and 438 F g^?1 and areal capacities 10.6 and 4.9 mAh cm^?2, respectively. Exceptional stabilities were also recorded for the composite samples (87.2% and 84.4% for Cu@MnO₂ and Co@MnO₂ thin film electrodes, respectively) against the pure MnO₂ film electrode sample (77.8%), after 2000 cycles. In addition, the short time constants (1.27 s and 1.31 s) were respectively realized for the fabricated Co@MnO₂ and Cu@MnO₂ electrode films as against the pure MnO₂ electrodes (4.35 s). These features observed in the composite electrode samples demonstrated an exhibition of faster ion response and higher rate capability by the samples. Moreover, the incorporation of Co into the MnO₂ electrode material relatively improved the supercapacitive activeness by enhancing the charge transition and transport.     

Fabrication of Tiron‐doped polypyrrole/MWCNT composite electrodes with high mass loading and enhanced performance for supercapacitors

In this study, the aromatic sulfonate compound Tiron with high charge to mass ratio is used as an anionic dopant for synthesis of polypyrrole (PPy). The fabricated PPy is investigated for electrochemical supercapacitor (ES) application. Testing results show that Tiron allows reduced PPy agglomeration, smaller particle size and improved charge storage properties of PPy. High capacitance and improved capacitive retention at high scan rates are achieved by the fabrication of PPy/multiwalled carbon nanotube (MWCNT) composite electrode using safranin (SAF) as a co‐dispersant. The Tiron‐doped PPy electrode shows the highest capacitance of 7.8 F cm^?2 with a mass of 27 mg cm^?2. The Tiron‐doped PPy/MWCNT composite electrode shows good capacitance retention with a capacitance of 1.0 F cm^?2 at the scan rate of 100 mV s^?1. Symmetric supercapacitor cells are fabricated using PPy based active materials. An energy density of 0.36 mWh cm^?2 is achieved. The energy/power density and capacitance retention of the Tiron‐doped PPy/MWCNT ES is significantly improved in comparison with PPy‐based ES, prepared without Tiron or MWCNT. The Tiron‐doped PPy/MWCNT symmetric supercapacitor presents good cycling performance with 91.4% capacitance retention after 1000 charge–discharge cycles. The PPy/MWCNT composites, prepared using Tiron and SAF co‐dispersant, are promising electrodes for ES. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42376.     

Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 mF.cm^-2 for open pore and approximately 180 mF.cm^-2 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles.     

Structural rearrangement by Ni,Cr doping in zinc cobaltite and its influence on supercapacitance

Transitional metal oxides are prevalent in the energy storage devices due to their remarkable electrochemical activity and charge storage capability. In this study, a spinel structured zinc cobaltite (ZnCo₂O₄) is doped with Ni and Cr to form a novel (Ni,Cr:ZnCo₂O₄) electrode material towards supercapacitor (SC) applications. Dopants served as a conductivity booster, particle size reducer and active sites provider benefitting the electrochemical activity. Comparatively, the doped sample delivered a higher capacitance value of 575 Fg^-1 in the potential range of 0–0.6V with 1 M KOH solution as an electrolyte which is higher than that of the pristine material and better cyclic stability is improved from 82.2% to 90.24% for 2000 cycles. The specific capacitance value of 30 Fg^-1 and 73 Fg^-1 at 0.75 Ag^-1 is achieved for the fabricated asymmetric supercapacitor device with Ni,Cr:ZnCo₂O₄ using Cu foil and Ni foam as current collector respectively. The device assembled with doped sample using Ni foam current collector has an energy density of 16.3 WhKg^?1 and a power density of 0.9 KWKg^?1 superseding the performance of the devices constructed with the pristine ZnCo₂O_4. The performance of Ni and Cr doped spinel structured zinc cobaltite device indicates a notable progress towards the direction of better performance supercapacitor applications.     

Electrochemical energy storage performance of heterostructured SnO2@MnO2 nanoflakes

In this work, we report synthesis of SnO₂@MnO₂ nanoflakes grown on nickel foam through a facile two-step hydrothermal route. The as-obtained products are characterized by series of techniques such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-obtained SnO₂@MnO₂ nanoflakes are directly used as supercapacitor electrode materials. The results show that the electrode possesses a high discharge areal capacitance of 1231.6 mF cm⁻² at 1 mA cm⁻² and benign cycling stability with 67.2% of initial areal capacitance retention when the current density is 10 mA cm⁻² after 6000 cycles. Moreover, the heterostructured electrode shows 41.1% retention of the initial capacitance when the current densities change from 1 to 10 mA cm⁻², which reveals good rate capability. SnO₂@MnO₂ nanoflakes products which possess excellent electrochemical properties might be used as potential electrode materials for supercapacitor applications.     

Micro-supercapacitors based on three dimensional interdigital polypyrrole/C-MEMS electrodes

Symmetric micro-supercapacitors with three dimensional (3D) interdigital electrode structures have been designed and fabricated through Carbon-microelectrochemical system (C-MEMS) technology. The micro-supercapacitor consists of a 3D C-MEMS structure which serves as a high effective surface area current collector and conformal polypyrrole (PPy) films deposited on the carbon structures as electroactive materials. The electrochemical performance of single electrodes and symmetric micro-supercapacitor cells were evaluated by cyclic voltammetry (CV) at different scan rates and galvanostatic charge/discharge tests. The effect of the 3D electrode structure on the performance of the micro-supercapacitor was studied. Single PPy/C-MEMS electrodes presented a specific capacitance of 162.07 ± 12.40 mF cm⁻² and a specific power of 1.62 ± 0.12 mW cm⁻² at 20 mV s⁻¹ scan rate. The symmetric micro-supercapacitor cells exhibited an average specific capacitance of 78.35 ± 5.67 mF cm⁻² and a specific power of 0.63 ± 0.04 mW cm⁻² at 20 mV s⁻¹ scan rate, demonstrating that 3D micro-supercapacitors are promising for applications that require high power in a limited footprint area of the device.     

Preparation of ordered mesoporous nickel oxide film electrodes via lyotropic liquid crystal templated electrodeposition route

A novel electrochemical route to fabricate ordered mesoporous metal oxide film electrodes has been investigated with particular reference to nickel oxide. Ordered mesoporous nickel oxide films are successfully synthesized by templated electrodeposition of H_I-e nickel hydroxide and followed by heat-treatment in air at various temperatures. The films are characterized physically by thermogravimetry (TG), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The applicability of this film as inexpensive and high-performance supercapacitor electrode material is demonstrated by the electrochemical characterization using cyclic voltammetry (CV) and chronopotentiometry technique. The specific capacitance of the nickel oxide film depends on the annealing temperature, showing a maximum value of 590 F g⁻¹ when the as-deposited film is heat-treated at 250 °C for 1.5 h.     

Synthesis and plasma treatment of nitrogen-doped graphene fibers for high-performance supercapacitors

Graphene fiber-based supercapacitor has aroused great interest as a flexible power source in future wearable electronics. However, the low electrochemical performance of graphene fibers (GFs) usually causes the serious limitation of use in practical applications due to the material stacking, hydrophobicity and fabrication process complexity. In this work, a facile and effective plasma-assisted strategy is put forward to increase specific surface area, tune hierarchically porous structure and promote wettability of nitrogen-doped graphene fibers (NGFs), resulting in the improvement of electrochemical performance. The supercapacitor assembled from plasma-treated NGFs shows superior capacitance (878 mF/cm² at 0.1 mA/cm² current density) and high energy density (19.5 μW h/cm² at 40 mW/cm² power density), which is 23.7% and 131.4% higher than that of NGFs and GFs, respectively. Additionally, the fiber-based supercapacitor based on plasma-treated NGFs exhibits high rate capability of 59.8% and excellent cyclic performance (95.8% retention over 10,000 cycles). These plasma-treated NGFs can be promising candidates for high-performance and flexible power sources in future wearable electronics.     

Novel one-step synthesis for 3-D four-pointed micro-star of quaternary metal (Mo–V–Mn–Ag) oxide electrode for asymmetric supercapacitor

An intention of the present work is to synthesize a quaternary metal oxide by a simple and cost-effective method. MoVMnAg-oxide@Ni-foam is synthesised by one-step hydrothermal method. The as-deposited MoVMnAg-oxide sample is systematically examined through XRD, FESEM, EDS-mapping, and TEM analysis. The electrochemical performance of an MoVMnAg@Ni-foam electrode is tested using CV, GCD, and EIS techniques. MoVMnAg-oxide@Ni-foam has a considerable high areal capacitance of 651 mFcm^?2 with 0.13 mWhcm^?2 energy at 1.8 mWcm^?2 power density in 1 M KOH electrolyte calculated from GCD curves. Also, the electrode shows a diffusion coefficient of 1.52 × 10^?7 cm²s^?1 along with 91 % of diffusive-controlled contribution and a b-value of 0.51, which depicts faradaic charge storage mechanism. An assembled asymmetric supercapacitor device (MoVMnAg@Ni-foam//AC) delivers an areal capacitance of 312 mFcm^?2 with 0.37 mWcm^?2 power density at 1 mAcm^?2 current density within 0 – 1.5 V voltage window. The asymmetric device showed cyclability and coulombic efficiency of 80.3% and 95% respectively measured up to 10,000 GCD cycles. These results demonstrate the deposition of quaternary metal oxide directly on Ni-foam showing highly competitive electrochemical performance so that they can be utilized in energy storage applications.