Pseudocapacitive Electrode Materials Research Articles

Hydrothermal synthesis of rGO-decorated NiMn2O4 nanoneedles for high-performance positive electrode in asymmetric supercapacitors

Pseudocapacitive electrode materials inherently have low electron conductivity, which prevents an energetic material from being fully utilised. We were able to produce effective hierarchical NiMn2O4/rGO composites, which provide an appealing solution to this issue. The composites were synthesised using a one-step hydrothermal approach. Due to the high electrical conductivity of reduced graphene oxide (rGO), the needles on plate like morphology of NiMn2O4, and the strong hold of dynamic materials to the current collector, the resulting hybrid electrodes exhibit a specific capacitance of 1628 Fg−1 at a current density of 1 Ag−1. They also demonstrate excellent rate performance and remarkable cycling stability, with a capacitance retention of 97.4 % after 10,000 cycles. In addition, the NiMn2O4/rGO//AC asymmetric supercapacitor (ASC) exhibits a peak energy density of 45Whkg−1 when operated at a power density of 3240 Wkg−1. The ASC device has an impressive ultralong cycling life, with a capacitance retention rate of 89.1 % after undergoing 10,000 charge/discharge cycles. The NiMn2O4/rGO composites provide a scalable production method and demonstrate outstanding electrochemical performance. This presents an opportunity to create innovative hybrid electrodes for enhanced supercapacitors.

Supercapacitor performance of pure and Ni-doped CuO electrodes prepared by USP

Abstract In this study, the ultrasonic spray pyrolysis (USP) technique was employed to fabricate pure and 3% Ni-doped copper oxide (CuO) thin films (TFs) on In2O3/SnO2 (ITO) coated glass substrates. X-ray diffraction (XRD) analysis revealed that both pure and 3% Ni-doped CuO TFs exhibit a polycrystalline structure with the tenorite phase oriented preferentially along the (111) plane. The morphological properties of these TFs were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) imaging. Energy dispersive x-ray spectroscopy (EDX) confirmed that the deposited TFs achieved the desired stoichiometry. The electrochemical properties of both pure and 3% Ni-doped CuO TFs were evaluated using cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). At a current density of 1 A g−1, the specific capacitance of pure CuO TFs was found to be 78 F g−1, decreasing to 2 F g−1 at 10 A g−1. In contrast, Ni-doped CuO TFs exhibited a specific capacitance of 722 F g−1 at 1 A g−1 and 20 F g−1 at 10 A g−1. These results indicate that Ni-doping significantly enhances the specific capacitance values. The superior performance of Ni-doped CuO electrodes is attributed to their uniformly high porosity and improved electrical conductivity, demonstrating Ni-doped CuO as an optimal electrode material for pseudocapacitors.

Exploring the Electrochemical Superiority of V2O5/TiO2@Ti3C2-MXene Hybrid Nanostructures for Enhanced Lithium-Ion Battery Performance.

The use of vanadium(V)-based materials as electrode materials in electrochemical energy storage (EES) devices is promising due to their structural and chemical variety, abundance, and low cost. V-based materials with a layered structure and high multielectron transfer in the redox reaction have been actively explored for energy storage. Our current work presents the structural and electrochemical properties of a vanadium-based composite with TiO2@Ti3C2 MXene, referred to as VM. This composite is obtained through the in situ thermal decomposition of the VO2(OH)/Ti3C2mixture, which is achieved by solution mixing and drying. The material structure is confirmed using various characterization tools, which establish an orthorhombic V2O5 nanostructure compositing with nanocrystalline TiO2@Ti3C2. VM with 5 wt % MXene, referred to as VM5, can achieve 460 mAhg-1 at a current density of 0.1 Ag1- and 290 mAhg-1 at 1 Ag1-, with an average coulombic efficiency of 98.5%. The presence of the V2O5/TiO2 (nanocrystals) heterojunction attached with Ti3C2 sheets contributed to reduced charge transfer resistance. The cyclic stability shows a capacity retention of 62% over 500 cycles at 1 Ag1- (4C rate, where 1C equals 0.25 Ag1-) with a 0.22 capacity drop with each cycle. Dunn's approach to examining the charge storage mechanism demonstrates 72% contribution of the surface-dominant capacitive process and 28% of the diffusion-controlled intercalation process at 0.4 mVs-1, suggesting a potential high-performance pseudocapacitive hybrid electrode material for lithium-ion batteries.

Nd-Ions Role in Structural Engineering and Capacitive Contributions of NiO Nanosheets Clusters as Excellent Pseudocapacitor Electrode Material

Nd-Ions Role in Structural Engineering and Capacitive Contributions of NiO Nanosheets Clusters as Excellent Pseudocapacitor Electrode Material

WO3 Nanoparticle/Biomass Derived N‐Doped Activated Carbon Decorated with Polyaniline Nanofibers Ternary Nanocomposite for High‐Performance Symmetric and Asymmetric Supercapacitor

AbstractSupercapacitors have captured the curiosity of researchers due to their extremely high energy storage capacity. Hybrid supercapacitors deliver high specific capacitance values compared to the exciting (electrical double layer capacitor) EDLC and pseudocapacitors. This work presents a simple and scalable synthetic method to design a hybrid ternary composite as electrode material. In this work, the combination of EDLC‐type behaviour material, i. e., sustainable biomass‐derived Nitrogen‐doped activated carbon (NAC) and pseudocapacitive behaviour electrode materials, i. e., metal oxides (tungsten oxide) and conductive polymer (polyaniline) are selected to achieve a high gravimetric capacity. The PANi/WO3/NAC (PWNAC) ternary composite is tested for symmetric and asymmetric supercapacitor (ASC). In a symmetric capacitor, PWNAC acts as both the positive and negative electrode, whereas in ASC, PWNAC acts as the positive electrode and NAC as the negative electrode. It is observed that the ASC shows a better capacitance value than symmetric. ASC operates at a potential range of 1.4 V in 1 M H2SO4 aqueous electrolyte, shows a maximum capacitance of 608.2 F/g at 0.5 A/g, and has long capacitance retention of 98.32 % of its initial capacitance after 2000 charge‐discharge cycles.

In-situ synthesis of synergistic ZnMn2O4/MnOOH nanocomposite as a cutting-edge pseudocapacitive electrode material for all-solid-state asymmetric supercapacitors

Currently, there has been a growing interest in constructing metal oxide composite structures through the in-situ synthesis method, especially for fabricating electrode materials for supercapacitors. This approach offers several advantages, such as improved contact between different materials, enhanced conductivity, efficient ion diffusion, and better overall electrochemical performance. This work investigates the synthesis of zinc manganese oxide and manganese oxyhydroxide (ZnMn2O4/MnOOH) composite using a solvothermal method. The structure, surface morphology, and composition of the ZnMn2O4/MnOOH composite were elucidated using standard physicochemical characterization techniques where the presence of ZnMn2O4 and MnOOH phases was confirmed and the ZnMn2O4/MnOOH nanocomposite behaved as a pseudocapacitive electrode with a notable specific capacitance of 1039.2 F g⁻1 at a current density of 1 A g⁻1. When subjected to a 10-fold increase in current density, the ZnMn2O4/MnOOH electrode maintained 50 % of its initial capacity, registering 513.4 F g⁻1. Additionally, the electrode showcased excellent cyclic stability, preserving 95 % of its initial capacity after 5000 cycles at 10 A g⁻1. Moreover, the constructed ZnMn2O4/MnOOH//activated carbon (AC) asymmetric supercapacitor (ASC) device attained a high energy density of 29.45 Wh kg⁻1 at a power density of 1384.5 W kg⁻1. The results confirm that the ZnMn2O4/MnOOH composite, prepared in a single synthesis step, shows great potential as a phenomenal pseudocapacitive electrode for energy storage applications.

Mechanosynthesis of pseudocapacitive MnCO3 and CoCO3 electroactive materials

Transition metals are known for their enormous potential as electrode materials for supercapacitor applications, however anhydrous carbonate minerals, namely Mn-carbonate, and Co-carbonate, are less explored and exhibit competitive energy storage performance compared to oxide and hydroxide forms. For the first time, MnCO3 (Rhodochrosite), CoCO3 (Spherocobaltite) and MnCo mixture (Mn1-xCoxCO3) were synthesized via mechanochemistry by a one-pot approach and used to prepare pseudocapacitive electrode materials for electrochemical energy storage. In this work, these materials were tested in alkaline electrolyte, and the morphological and structural features of the materials were examined using SEM (Scanning Electron Microscope), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). The surface composition was studied by X-ray photoelectron spectroscopy (XPS). After milling, the microstructures showed an increase in dislocations and microstrains in their crystal lattices which influenced the electrochemical performance. The crystallinity of the carbonate materials was also affected by grinding. In 1 M KOH electrolyte, milled MnCO3 evidenced the highest specific capacitance (354.3 F/g at 1.0 A/g), while milled CoCO3, revealed impressive capacitance retention of 94.8 % after 20000 continuous charge–discharge cycles at 10 A/g. Interestingly, the composite (Mn-Co)CO3 evidenced superior rate capability (58.8 %) and enhanced capacitance retention under cycling compared to the individual cobalt and manganese carbonates. The results evidence the excellent electrochemical behavior of Mn and Co carbonates prepared by a simple, low-cost, and green route and prove their potential as electroactive electrode materials for electrochemical energy storage applications, particularly pseudocapacitors.

Carbon-modified NiCo2O4 as an electrode material for supercapacitors

Transition metal oxides are a promising class of electrode materials for pseudocapacitors due to their high electrochemical activity and eco-friendly nature. However, they possess poor intrinsic conductivity which results in the low energy density of the assembled supercapacitors. In this study, electrodes composed of amorphous C-modified NiCo2O4 (C/NiCo2O4/NF) on nickel foam substrate were prepared by electrochemical deposition and thermostatic heating method. The incorporation of amorphous C compensates for the low electrical conductivity of NiCo2O4 materials, thereby significantly enhancing the electrochemical performance. The galvanostatic charge-discharge (GCD) test results reveal an impressive specific capacitance of 379.4 mF/cm2 at a current density of 1.5 mA/cm2, and with a capacitance retention rate of 87.1 %. In addition, the symmetric supercapacitor assembled using C/NiCo2O4 electrode materials exhibits exceptional energy density and power density, reaching maximum values of 522.3 μWh/cm2 and 900 μW/cm2 respectively. The device is capable of illuminating LED for up to 8 min, further demonstrating its practical applicability. These results underscore the feasibility and promise of C/NiCo2O4 as an electrode material for the advancement of high-performance supercapacitors.

Encapsulation hierarchical bimetallic oxide with flexible electrospinning carbon nanofibers for efficient capacitive deionization

Water scarcity, an intensifying issue, has spurred extensive research into the development of sophisticated freestanding pseudocapacitive electrode materials. Characterized by their precise morphology, intricate mechanics, and superior desalination capabilities, these materials are revolutionizing water treatment technologies. However, their broad adoption is hampered by complex fabrication processes and the necessity for various unique components. Herein, the paper introduces a streamlined method combining electrospinning and carbonization to produce a freestanding nitrogen-doped carbon nanofiber encapsulating manganese cobalt oxide (MCO) nanoparticles for desalination purposes. The approach significantly enhances interfacial interactions, mitigates volume shifts during sodium ion adsorption and desorption, and strengthens interfacial stability. Benefiting from its structural and compositional merits, the optimal MCO-1.0 electrode showcases exceptional electrochemical attributes. It achieves an impressive desalination efficiency (34.68 mg g−1), swift capacitive deionization rate (0.58 mg g−1 min−1), and superior cyclic durability. The study enhances our understanding of freestanding carbon fibers encapsulated with metal oxide nanoparticles, a key step toward developing robust electrodes for industrial applications.

Redox-active “Structural Pillar” molecular doping strategy towards High-Performance polyaniline-based flexible supercapacitors

To coordinate flexibility to electrodes without sacrificing their electrochemical properties is critical for the development of wearable supercapacitors (SCs). Polyaniline (PANI) is well-known pseudocapacitive electrode material due to its high conductivity and different oxidation states upon switchable structures. However, its rigid conjugated backbone and structural instability caused by repeated doping/de-doping during cycling severely impede its utilization in flexible SCs. Herein, we deploy a directional freezing and redox-active “structural pillar” molecular doping strategy to boost PANI-based flexible SCs with high performance. The directional freezing strategy constructs an interconnected 3D honeycomb hydrogel structure with PANI nanofibers, which guarantees fast ion diffusion and electron transport and meanwhile exposes abundant active sites. The large-sized dopant 2-amino-4-bromoanthraquinone-2-sulfonic acid sodium (AQNS) is used as the structural pillar to alleviate the structural instability of PANI during cycling and provides additional pseudocapacitance arising from its redox active quinone groups. Moreover, the negatively charged −SO3− on AQNS can further interact with H+ in the electrolyte to act as an internal proton reservoir, assisting the protonation of –NH- and −N = in PANI to facilitate its charge storage process. Consequently, the PANI-AQNS electrode achieves a high specific capacitance of 578 F g−1 at 1 A g−1 and its symmetric SCs exhibit a specific capacitance of 199 F g−1 at 0.5 A g−1 with an energy density of 13.61 W h kg−1 at a power density of 175 W kg−1. Upon 2000 cycles of dynamic deformations, the SCs can still maintain above 90 % of the initial capacitance, verifying their excellent flexibility-relevant property.

Enabling extreme low-temperature proton pseudocapacitor with tailored pseudocapacitive electrodes and antifreezing electrolytes engineering

A critical current challenge in the development of proton pseudocapacitors is developing antifreezing electrolytes and high-performance proton storage materials in extreme environments. Here, we design an antifreezing proton pseudocapacitor using a high-concentration phosphoric acid electrolyte and pseudocapacitive electrode materials, which delivers an outstanding rate capacity and cycle life below − 40 °C. Comprehensive physical characterization techniques and theoretical simulations demonstrate that the solvation structure of the electrolyte defines the freezing point and electrochemical stability window, which is crucial for achieving fast charge carrier mobility and avoiding side effects. The pseudocapacitive hydrated tungsten oxide anodes and Prussian blue analogue cathodes with their open crystal structures achieve fast proton transport and storage, resulting in excellent electrochemical performance from − 60 to 25 °C (1000 cycles with no capacity fading at − 40 °C). Benefiting from the synergistic effect between the electrolyte and electrode materials, the fabricated proton pseudocapacitors exhibit remarkable low-temperature electrochemical performance. It achieves a maximum energy density of 39 Wh kg−1 and a broadened electrochemical window from 1.7 V at 25 °C to 2.3 V at − 60 °C. This work provides a comprehensive strategy to develop high-performance proton energy storage devices under ultralow-temperature conditions.

Single‐Step One‐Pot Synthesis of NiCo2O4/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material.

Cobalt‐based zeolitic imidazole framework derived hollow Co3S4 nanopolyhedrons for supercapacitors

Transition metal sulfides with designed nanostructures are expected to provide superior electrochemical performance when used as electrode materials for pseudocapacitors compared to their oxide counterparts. In this paper, hollow Co3S4 dodecahedra were successfully prepared using cobalt‐based zeolite imidazolium skeleton (ZIF‐67) as the precursor and thioacetamide (TAA) as the sulfur source combined with a facile one‐step vulcanization process. The hollow cavity structure not only shortens the carrier transport distance but also provides a higher specific surface area and abundant active sites, which promotes an efficient mass transfer process. In addition, the one‐step synthesis of hollow Co3S4 has greater advantages than the one‐step synthesis in terms of cost control and process simplification. The specific capacitance of the produced hollow Co3S4 nanopolyhedra was 668 F/g at 1 A/g and remained at 353 F/g at 10 A/g when used as a pseudocapacitor electrode, demonstrating its superior multiplication capability. In addition, the capacitance retention is 86.4% after 5000 cycles at 4 A/g, indicating its long cycle stability. Notably, employing commercial activated carbon as negative electrode and the as‐prepared hollow Co3S4 polyhedrons as positive electrode, the assembled asymmetry supercapacitor device delivers a high energy density of 20.7 Wh/kg at a power density of 716 kW/kg. The capacitance value of the device remains up to 81.4% after 2000 charging/discharging cycles. The simple synthesis process opens new opportunities to develop advanced hollow nanostructures exhibiting potential for various applications.

Enhanced supercapacitor potential of CeO2/MXene nanocomposites with tunable conductive polyaniline concentrations

In this paper, a scalable hydrothermal and in-situ polymerization method is described for the development of CeO2/MXene/PANI-based nanocomposites. Five samples CeO2, CeO2/MXene, three ternary composites namely (CeO2/MXene)/PANI 80 %:20 % (CMP1), (CeO2/MXene)/PANI 60 %:40 % (CMP2) and (CeO2/MXene)/PANI 40 %:60 % (CMP3) are prepared. The synthesized materials are characterized using advanced techniques to reveal their diverse properties and potential applications. The CMP3 composite exhibits a lower band gap energy of up to 2.19 eV in the optical study. Moreover, this material's high capacitance and dielectric constant of 169.9 make it beneficial for capacitors. It also offers the lowest charge transfer resistance of all the as-prepared samples, a high specific capacitance of 2247.962 Fg−1, remarkable rate capability, and excellent cycle life, maintaining 91 % after 6000 cycles. Its remarkable performance is caused by the even distribution of its extremely porous morphology and enhanced electrical conductivity. This work suggests that CMP3 is the best electrode material for pseudocapacitors.

Magnetron Sputtered SnO₂ Layer Combined with NiCo−LDH Nanosheets for High‐Performance All‐Solid‐State Supercapacitors

AbstractNickel‐cobalt layered double hydroxide (NiCo−LDH) has attracted much attention because of its excellent electrochemical properties and regulability. And it is a potential pseudocapacitive electrode material, which is commonly used in supercapacitors and lithium‐ion batteries. Its application in the field of supercapacitors can improve the energy density, power density and cycle life of devices. However, NiCo−LDH still faces some challenges, such as poor electrical conductivity and the capacity attenuation caused by agglomeration of layered structures, which require further research and optimization. In this paper, SnO2 films were prepared on carbon cloth (CC) by magnetron sputtering method, and Ni−Co LDH nanosheets were grown by hydrothermal reaction to obtain NiCo−LDH@SnO2 composites. Due to the synergistic effect between NiCo−LDH and SnO2, NiCo−LDH@SnO2 composites exhibit high Cs and good cyclic stability. In addition, an all‐solid‐state flexible asymmetric supercapacitor (ASC) was assembled with activated carbon (AC) anodes, showing good specific capacitance(Cs) and energy density. And a high initial capacitance can still be retained after 10,000 cycles. This paper shows that NiCo−LDH@SnO2 shows excellent application potential in supercapacitors.

Improved electrochemical performance of hydrothermally synthesized Zn-Ni-S/rGO nanocomposite as an electrode for supercapacitor application

This present work reports on the hydrothermal synthesis of zinc-nickel sulfide with reduced graphene oxide (Zn-Ni-S/rGO) nanocomposite for supercapacitor applications. The synthesized samples are evaluated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), and high-resolution scanning transmission electron microscopy (HR-TEM), which are employed to examine the structure, morphology, and chemical composition of the Zn-Ni-S/rGO nanocomposite. The XRD results indicates formation of high crystalline Zn-Ni-S/ rGO nanocomposites. FE-SEM equipped with an EDX spectrum, illustrates a spherical morphology of Zn-Ni-S combined with a thin layer of rGO in the form of composite nature. Furthermore, elemental composition of Zinc, Nickel, Sulfur and Carbon presence in the EDS spectra further supports the formation of Zn-Ni-S/rGO nanocomposite. The electrochemcial properties of ZnS and Zn-Ni-S/rGO nanocomposite are studied through cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. High specific capacitance of 284 F/g is obtained at 11 mA g−1 current density. The Zn-Ni-S/rGO nanocomposite demonstrates high capacitance retention of 96 % over 3,000 cycles. The potential application of the Zn-Ni-S/rGO nanocomposite as an efficient electrode material for pseudocapacitors is supported by its favourable performance.

Electrochemical potential of chitosan nanoparticles obtained by the reverse micellar process

Chitosan nanoparticles are synthesized by the reverse micellar technique using heptane as solvent and hexamine as surfactant. XRD, FTIR, and SEM/EDAX analyses are performed to investigate the structural and morphological behavior of chitosan nanoparticles. XRD shows the crystalline nature of the materials with peaks appeared at 2θ =17.8 °, 25.5 °, 31.2 °, 36.4 °, 44.7 °, and 48.5 °. The average crystallite size of obtained chitosan nanoparticles is 25 nm. The identification of functional groups in both pure chitosan and chitosan nanoparticles are compared using FTIR analysis. Noticed at wavenumbers 3435 cm−1 and 3460 cm−1 corresponds to the stretching vibration of the –NH2 and –OH functional groups. SEM shows the uniform morphology of the materials and EDAX shows the presence of various elements (carbon, nitrogen, oxygen, aluminum and chlorine) in both the materials. The electrochemical behavior of the nanoparticles was analyzed by cyclic voltammetry analysis and galvanostatic charging/discharging. Electrochemical faradaic performance identifies chitosan nanoparticles as effective electrode materials in pseudo capacitors.

Work-function-prompted interfacial charge kinetics in hierarchical heterojunction flexible electrode for efficient capacitive deionization

The growing challenge of water scarcity has spurred extensive research into the development of advanced freestanding pseudocapacitive electrode materials. These electrodes, characterized by their controlled morphology, mechanical complexity, and enhanced desalination capabilities, are advancing water treatment technologies. Additionally, electrodes with interfacially influenced heterostructures demonstrate substantial potential to enhance electrochemical kinetics. However, their widespread adoption is hindered by intricate synthesis procedures and the necessity for multiple discrete components. Herein, the report introduces a cohesive approach that utilizes electrospinning and carbonization to create a freestanding, hierarchically porous nitrogen-doped carbon nanofiber network encapsulating FeNi3 alloy (FeNi3@CNFs) for desalination applications. The method enhances the interfacial effect, mitigates volume changes during sodium ion adsorption and desorption, and improves interfacial stability. By capitalizing on structural and compositional advantages, the novel FeNi3@CNFs electrode delivers outstanding electrochemical properties, including a high desalination capacity (46.47 mg g−1 at 1.2 V), rapid desalination rate (0.77 mg g−1 min−1), and enhanced cyclic durability. Computational analysis via Density Functional Theory shows that the work function prompts a surface charge redistribution at the FeNi3@CNFs heterojunction, optimizing the surface electronic structure and reducing the energy barrier for adsorption. The modification significantly boosts the diffusion kinetics of sodium adsorption. The study delineates a comprehensive methodology for fabricating high-performance heterostructured electrode materials that are effective for capacitive deionization.

Machine Learning-Assisted Survey on Charge Storage of MXenes in Aqueous Electrolytes.

Pseudocapacitance is capable of both high power and energy densities owing to its fast chemical adsorption with substantial charge transfer. 2D transition-metal carbides/nitrides (MXenes) are an emerging class of pseudocapacitive electrode materials. However, the factors that dominate the physical and chemical properties of MXenes are intercorrelated with each other, giving rise to challenges in the quantitative assessment of their discriminating importance. In this perspective, literature data on the specific capacitance of MXene electrodes in aqueous electrolytes is comprehensively surveyed and analyzed using machine-learning techniques. The specific capacitance of MXene electrodes shows strong dependency on their interlayer spacing, where confined H2O in the interlayer space should play a key role in the charge storage mechanism. The electrochemical behavior of MXene electrodes is overviewed based on atomistic insights obtained from data-driven approaches.

Facile synthesis of bismuth niobium oxide (Bi3NbO7) micro squares as a novel pseudocapacitive electrode material for supercapacitors

Herein Bi3NbO7 micro squares were prepared by a simple solvothermal method, and their electrochemical performances towards supercapacitor application were assessed. XRD, Raman, XPS, FESEM and TEM analysis were performed as the confirmation studies for the Bi3NbO7. The electrochemical measurements specified that the maximum specific capacitance value of 596 Fg−1 at a given current density of 2 Ag−1, and an outstanding cycling stability of ∼ 90 % capacitance retention over 2000 cycles at 10 Ag−1 were achieved. Hence, the single-component Bi3NbO7 electrode material has been considered as alternate material for supercapacitor applications.