Supercapacitors Research Articles

Constructing hollow cobalt sulfide nanocages strung by manganese molybdate nanorods for high-efficiency supercapacitors and electrocatalytic methanol oxidation

Constructing core-shell heterostuctures with rationally designed nanoarchitectures and components is a promising strategy to pursuit high-efficiency energy storage and conversion in supercapacitors (SCs) and direct methanol fuel cells (DMFCs). Herein, a multi-dimensional MnMoO4@CoS core-shell heterostructure is designed and synthesized by stringing metal-organic framework-derived hollow CoS nanocages with MnMoO4 nanorods. Such heterostructure provides more electroactive sites and enhanced structural stability. Theory calculations unveil that the work function difference between MnMoO4 and CoS induces the charge redistribution and modulate interfacial electronic configuration in the MnMoO4/CoS heterojunction. Meanwhile, a interfacial built-in electrical field is established, enhancing interfacial charge transfer efficiency and promoting the surface adsorption of electrolyte ions. By integrating all these advantages, the MnMoO4@CoS electrode demonstrates enhanced rate capacities (933 C g−1 at 1 A g−1 and 623 C g−1 at 10 A g−1) and cycling durability (90.3 % capacity retention after 10,000 cycles) compared to bare MnMoO4 and CoS electrodes. Moreover, the MnMoO4@CoS electrode exhibits an appreciable electrocatalytic performance for methanol oxidation, with a current density of 294.8 mA cm−2 at 10 mV s−1 and 96.6 % current retention after 10,000 s. Our work offers a fundamental guideline for designing and engineering core-shell heterostructures with desirable electrochemical performance for SCs and DMFCs.

Optimizing Energy Solutions: Mott-Schottky Engineered 1D/3D CoWO4(OH)2·H2O/MoS2 Heterostructure for Advanced Energy Storage and Conversion Application.

Heterostructure engineering offers a powerful approach to creating innovative electrocatalysts. By combining different materials, it can achieve synergistic effects that enhance both charge storage and electrocatalytic activity. In this work, it is capitalized on this concept by designing a 1D/3D CoWO4(OH)2·H2O/molybdenum disulfide (CTH/MoS2) heterostructure. It is achieved this by in situ depositing 3D MoS2 nanoflowers on 1D CTH nanorods. To explore the impact of precursor choice, various sulfur (S) sources is investigated. Interestingly, the S precursor influenced the dimensionality of the MoS2 component. For example, L-cysteine (L-cys), and glutathione (GSH) resulted in 0D morphologies, thiourea (TU) led to a 2D structure, and thioacetamide (TAA) yielded a desirable 3D architecture. Notably, the 1D/3D CTH/MoS2-TAA heterostructure exhibited exceptional performance in both supercapacitors (SCs) and quantum dot-sensitized solar cells (QDSSCs). This achievement can be attributed to several factors: the synergetic effect between 1D CTH and 3D MoS2, improved accessibility due to the multi-dimensional structure, and a tailored electronic structure facilitated by the Mott-Schottky (M-S) interaction arising from the different material Fermi levels. This interaction further enhances conductivity, ultimately leading to the observed high specific capacity in SCs (154.44mAhg-1 at 3mAcm-2) and remarkable photovoltaic efficiency in QDSSCs (6.48%).

Synergistic Schottky contacts & diatomic doping in Cr/P-MoS2@Ti3C2Tx with boosted energy storage performance

Molybdenum disulfide (MoS2), despite its promising attributes, suffers from low conductivity and aggregation. Herein, we introduce a novel approach that integrates Schottky contacts with Cr/P diatomic doping in MoS2@Ti3C2Tx, significantly enhancing its performance. The Schottky contacts effectively suppress aggregation and accelerate interfacial charge transfer, while Cr/P doping boosts conductivity, active sites, and stability. As a result, the Cr/P-MoS2@Ti3C2Tx electrode exhibits a specific capacitance of 650 F g-1 at 1 A g-1, which is fourfold higher than that of pristine MoS2. When assembled into an asymmetric supercapacitor (Cr/P-MoS2@Ti3C2Tx//AC ASC), the device achieves a peak energy density of 32 Wh kg-1 at 303 W kg-1, maintaining 85% capacitance retention after 10,000 cycles with an impressive coulombic efficiency of 97%. Furthermore, the density functional theory (DFT) calculations validate the beneficial effects of Schottky contacts and diatomic doping on the improved energy storage performance of Cr/P-MoS2@Ti3C2Tx. This work demonstrates the promising potential of the material for applications in high-performance supercapacitors (SCs).

Hierarchical MnCo2O4@MnWO4 core-shell nanoarrays on Ni foam as binder-free electrode for asymmetric supercapacitors

Supercapacitors (SCs) are generally perceived as competitive possibilities for portable electronic products due to their exceptionally high power density and extended operational lifespan. Nevertheless, the relatively low energy density remains a crucial obstacle to its widespread application. A hierarchical MnCo2O4@MnWO4 core-shell nanoarrays on nickel foam (NF) was designed and synthesized by utilizing the MnCo2O4 nanosheet array as the backbone and the MnWO4 nanosheet array as the shell via hydrothermal procedure and calcination. The MnCo2O4@MnWO4/NF electrode achieves 1428.5 F g−1 at 1 A g−1 with 97.8 % of its pristine capacity after 4000 cycles. The superior energy storage characteristic is a result of several factors, including the binder-free integrated electrode design, the synergistic effect between MnCo2O4 and MnWO4, and abundant active sites. The assembled asymmetric supercapacitor (ASC) has an energy density of 36.46 Wh kg−1 at 750 W kg−1, and 85.4 % capacity reserved after 5000 cycles.

Synthesis, characterization and application of CNTs@Co-MOF and FCNTs@Co-MOF as superior supercapacitor: Experimental and theoretical studies

Supercapacitor offers high power density and quick charge/discharge speed. Herein, a cobalt-metal organic framework (Co-MOF) is synthesized, and the chemical structure is investigated via XRD, FTIR, XPs, and SEM-EDX. Photoluminescence and diffuse reflectance spectroscopy measurements determine the optical properties and band gap. The band gap of Co-MOF is calculated and found to be 1.94 eV, indicating its capability to be applied as a supercapacitor. Carbon nanotubes (CNTs) and functionalized carbon nanotubes (FCNTs) are mixed with Co-MOF to form CNTs@Co-MOFs and FCNTs@Co-MOFs, respectively. The performance of these MOFs as supercapacitors is evaluated using electrochemical measurements. According to the analysis of the super capacitance of the synthesized compounds, FCNTs@Co-MOF shows the highest specific supercapacitance of 454 F g−1, whereas Co-MOF and CNTs@Co-MOF have 263 F g−1 and 338 F g−1, respectively. Besides, the semi-empirical quantum method is used to assess the relationship between the electronic and the experimental data. Experimental and theoretical results recommended the usage of the investigated MOFs as superior supercapacitors.

Coexistence of Redox‐Active Metal and Ligand Sites in Copper‐based 2D Conjugated Metal‐Organic Frameworks for Battery‐Supercapacitor hybrid systems

Two‐dimensional (2D) conjugated metal‐organic frameworks (c‐MOFs) are promising materials for supercapacitor (SC) electrodes due to their high electrochemically accessible surface area coupled with superior electrical conductivity compared to traditional MOFs. Here, porous and non‐porous HHB‐Cu (HHB=hexahydroxybenzene), derived through surfactant‐assisted synthesis, are studied as representative 2D c‐MOF models, showing different reversible redox reactions with Na+ and Li+ in aqueous and organic electrolytes, respectively. We deployed these redox activities to design negative electrodes for hybrid SCs (HSCs), combining the battery‐like property of HHB‐Cu as negative electrode and the high capacitance and robust cyclic stability of activated carbon (AC) as positive electrode. In organic electrolyte, porous HHB‐Cu‐based HSC achieves a maximum cell specific capacity (Cs) of 22.1 mAhg‐1 at 0.1 Ag‐1, specific energy (Es) of 15.55 Whkg‐1 at specific power (Ps) of 70.49 Wkg‐1, and 77% cyclic stability after 3000 gravimetric charge‐discharge (GCD) cycles at 1 Ag‐1 (calculated on the mass of both electrode materials). In the aqueous electrolyte, porous HHB‐Cu‐based HSC displays a Cs of 13.9 mAhg‐1 at 0.1 Ag‐1, Es of 6.13 Whkg‐1 at 44.05 Wkg‐1, and 72.3% Cs retention after 3000 GCD cycles. The non‐porous sample shows lower Es performance but better rate capability compared to the porous one.

Silicon Nanowires via Metal-Assisted Chemical Etching for Energy Storage Applications.

Silicon nanowires (SiNWs) have demonstrated great potential for energy storage due to their exceptional electrical conductivity, large surface area, and wide compositional range. Metal-assisted chemical etching (MACE) is a widely used top-down technique for fabricating silicon micro/nanostructures. SiNWs fabricated by MACE exhibit significant surface areas and diverse surface chemistry. Since the material composition and surface chemistry have a significant impact on the electrochemical energy storage performance, integrating SiNWs with diverse materials like porous carbon, metal oxides/sulfides, and polymers, can establish composites with excellent properties. Hence, it is imperative to meticulously fabricate SiNW-based materials with customizable morphologies and enhanced electrochemical energy-storage performance. This review provides an in-depth study of recent advancements in SiNW-based materials with enhanced performance for energy storage systems, such as supercapacitors (SCs) and lithium-ion batteries (LIBs). It includes a concise overview of the history, MACE synthesis, and characteristics of SiNWs. Further, it also explores the key elements that influence the MACE process of SiNWs and delves into structural engineering. Additionally, we introduce recent advances in SiNW-based materials for the design of high-performance energy-storage devices, namely SCs and LIBs. Finally, we present the crucial future prospects of SiNW-based materials for energy-storage applications.

Fabrication of modified laser-induced graphene using activated carbon and polyamic acid coating for flexible and high-performance microsupercapacitors

In this study, we developed a method to combine polyamic acid (PAA) and activated carbon (AC), which were then coated on laser-induced graphene (LIG). The material was heated to facilitate the conversion of PAA–AC into polyimide (PI)–AC. Then, the resulting material was subjected to a second laser irradiation process to obtain AC–LIG composite materials. The resulting material features a robust and flexible electrode architecture with a high surface area, improved ion accessibility, and enhanced charge transfer kinetics. In tests conducted with a three-electrode setup, the AC–LIG configuration exhibited a considerably high specific capacitance, reaching 97.2 mF cm−2 at 0.2 mA cm−2, which is approximately fourteen times larger than that of pristine LIG (7.1 mF cm−2). When integrated into a flexible microsupercapacitor using a polyvinyl alcohol (PVA)–H2SO4 (sulfuric acid) gel-type electrolyte, AC–LIG exhibited a higher specific capacitance (68.4 mF cm−2 at 0.3 mA cm−2) than d-LIG (17.1 mF cm−2 at 0.3 mA cm−2). Furthermore, AC–LIG showed good Coulombic efficiency (98.5 %) and capacitance retention (90.0 %) after 10,000 cycles. These results highlight the potential of AC–LIG as a viable alternative for advanced supercapacitor (SC) applications, providing improved energy storage capacities and a reliable performance.

Green synthesised Mn3O4 and poly (o-phenylenediamine) for antimicrobial textile-based supercapacitor applications

The advancement of wearable supercapacitors (SCs) has recently garnered a lot of attention owing to their ease of fabrication into textiles, low cost, long cycle life, fast charging and discharging, high efficiency, and ability to bridge the energy and power gap between conventional capacitors and batteries. The present study focuses on the development of wearable textile-based SC electrodes using green-synthesised manganese oxide nanoparticles functionalised on poly(o-phenylenediamine) reinforced to a polymer nanocomposite. The prepared nanocomposite was characterized using spectroscopic techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy, x-ray diffraction studies, and scanning electron microscopy to validate the incorporation of metal oxide nanoparticles into the polymer matrix. The thermal properties were studied using thermogravimetric analysis and differential scanning calorimetry. The electrochemical performance of the bare polymer and the nanocomposite was evaluated using cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy techniques. An impressive specific capacitance of 213 Fg-1was achieved at a current density of 1 Ag-1for the polymer nanocomposite and even after 1000 cycles a capacitance retention of 89% was observed. Enhanced antimicrobial activity was also observed for the nanocomposite against both gram-negative and gram-positive bacteria. Based on these attributes, the fabricated device can be used as an efficient antimicrobial wearable SC.

Nickel aluminum selenide wrapped by NiCoAl-layered double hydroxide enables a robust structure for supercapacitors

To explore a simple and convenient strategy for the construction of hybrid composites as advanced electrode materials for supercapacitors (SCs), this research realized the construction of nickel − aluminium selenide (NiAlSe)@NiCoAl-layered double hydroxide (NiCoAl-LDH) heterostructure. In-situ hybridization of NiCoAl-LDH nanosheets onto NiAlSe nanoparticles anchored on carbon cloth generates a special core–shell heterostructure, which enhances the exposure of active centers and increases the surface area. The formation of heterogeneous interfaces between NiAlSe and NiCoAl-LDH alters the electronic architecture and accelerates the electron/ion migration. By making full use of the structural benefits and the cooperative effect, the NiAlSe@NiCoAl-LDH composite electrode delivered a large capacitance (Cs) of 1789.2F/g at 1 A/g along with a high retention rate of 94.7 % over 5,000 cycles, which outperforms the bare NiAlSe and NiCoAl-LDH. Meanwhile, the assembled NiAlSe@NiCoAl-LDH hybrid supercapacitor (HSC) attained maximum specific energy (Es) of 71.5 Wh kg−1. This HSC device exhibits superior cyclic durability of 92.1 % after 30,000 cycles. Thereby, this research offers valuable insights into the construction of robust electrode materials for advanced HSC devices.

Self-sulfur doped mesoporous novel carbon electrodes derived from poly-anthraquinone sulfide for high-performance supercapacitors! A comparative study

Carbon materials are suitable electrode candidates in supercapacitors (SCs) because of their availability, well-defined microstructures, and ultrahigh surface areas. Herein, a universal chemical activation method was utilized to obtain activated carbon (C-KOH) from poly-anthraquinone sulfide (PAQS) at 850 °C and reduced activated carbon (C-KOH-H) from C-KOH via a mild hydrogen reduction process at low temperature. The electrochemical performances of the PAQS derived activated carbon electrodes were investigated by assembling electric double-layer capacitors (EDLCs). Electrodes fabricated from C-KOH and C-KOH-H showed 174 and 182.3 F g−1 specific capacitances at 0.5 A g−1 current density, respectively. Whereas their energy densities were 44 and 46 Wh kg−1 at 350 and 423 W kg−1 power densities, respectively. SCs assembled from C-KOH-H showed excellent rate performance, that retained 140 F g−1 even at high current density (20 A g−1), while the one assembled with C-KOH stored 54 F g−1. Furthermore, the C-KOH-H electrode retained 98 % of the initial capacitance at 1 A g−1 over 20,000 continuous cycles. The experimental results revealed that C-KOH-H showed the best electrochemical performance in SCs, which is attributed to the presence of less sulfur and oxygen than C-KOH after the mild reduction. These results prove that PAQS show excellent activation with KOH to produce well-organized porous activated carbons having high specific surface areas, which can be utilized as high-performance electrode materials in SCs.

An environment-friendly method to prepare fulvic acid-based porous carbon for high energy density supercapacitors

Low energy density (Eg) of supercapacitors (SCs) severely limits their industrial applications. Enhancing the voltage window of SCs is an effective method to achieve a square-fold increase in Eg. 3D hierarchical porous carbons (FPs) with high yield (14.5 %) and high conductivity (87 S m−1) were prepared by an interfacial self-assembly method using low-cost biomass fulvic acid (FA) as a carbon resource and employs P123 as a structure-directing agent. The soft template P123 establishes a key role in the formation of FPs. It not only enhances the pore connectivity of FPs but also induces an interfacial orientation of the carbon micro-domains in FA. Furthermore, high-temperature annealing can repair the carbon network of FPs, thus FPs are endowed with high electrical conductivity, low carbon defects and low oxygen content (4.1 at.%), which leads to superior voltage-withstanding properties. By exploiting its structural advantages, the optimized sample FP800 exhibits a specific surface area of 1938 m2 g−1, sp2 carbon (88.5 %), a high mesopore ratio of 30.76 % and a high voltage of 3.2 V in commercial TEABF4/PC electrolyte. It gets high Cg of 107 F g−1 at 1 A g−1, high rate performance (C10/0.05) of 82.0 % and maximum Eg of 39.1 Wh kg−1. Furthermore, it also obtains an ultra-stable lifespan with 90.6 % capacity retention after 60,000 cycles. Compared to FP750 and FP850, FP800 has a more reasonable electrochemical performance.

Facile synthesis of MWCNT hexagonal needles grown on interconnected honeycombs like MnCo2O4/MnO2 nanoporous electrode for high-performance asymmetric supercapacitor

The construction of a honeycomb-like structure composed of MnCo2O4/MnO2was effectively achieved using a combination of hydrothermal processing and heat treatment. The whole surface of the MnCo2O4/MnO2 honeycomb is coated with neatly arranged hexagonal nano needles made of MWCNT, leading to a substantial enhancement in the specific surface area. At 1 A/g, the supercapacitor electrode composed of MnCo2O4/MnO2@MWCNT composite exhibited an exceptional specific capacitance of around 1539 F/g. Furthermore, it maintained approximately 95.5 % of its capacity even after undergoing 10,000 cycles. The asymmetric capacitor device, with MnCo2O4/MnO2@MWCNT and AC electrode, has a power density of 1537.8 W kg−1 and an energy density of 48.78 Wh kg−1. The MnCo2O4/MnO2composite exhibits exceptional rate performance, significant capacitance, and excellent cycle performance due to the synergistic effect between MnCo2O4/MnO2 and MWCNT, as well as the high specific surface area and unique structure. Consequently, it presents a viable option for the advancement of high-efficiency electrochemical super capacitors in the next generation.

Surface engineered covalent bridging strategy to in-situ fabricate MXene-based core-sheath fiber for flexible supercapacitors with ultrahigh volumetric energy density and mechanical properties

MXene fiber-based supercapacitors (SCs) are expected to make a major contribution to the ongoing development of wearable electronics and metaverse technologies in future. However, to fabricate fiber electrodes with high energy density and strong mechanical properties remains a major challenge for their usage in SCs. Herein, we fabricated a flexible core-sheath structural Ti3C2Tx MXene@polyaniline (MX@PA) fiber electrode with ultrahigh volumetric energy density and good tensile strength through surface engineered covalent bridging strategy via wet spinning and in situ oxidant-freepolymerization processes. Benefiting from the high-order core-sheath structure and strong Ti-O-N covalent bonds between MXene and PANI, an ultrahigh tensile strength (∼168.1 MPa) and super-toughed (∼1.75 MJ cm−3) fiber electrode was achieved. The assembled SC provided much higher volumetric capacitance of 631F cm−3 (based on the SC device) at a current density of 0.5 A cm−3 and ultralong-term cycling stability with 92.6 % capacitance retention after 10000 cycles due to the rapid electron conduction of core (MXene) and large pseudocapacitive charge transfer of the sheath (PANI). As a result, the SC delivers excellent volumetric energy density of 56.1 mWh cm−3 at a power density of 204.9 mW cm−3. The integrated SC found actual application to power a 2.5 V red LED.

Optimal techno-economic assessment of isolated microgrid integrated with fast charging stations using radial basis deep learning

The global transportation electrification commerce sector is now booming. Stakeholders are paying an increased attention to the integration of electric vehicles and electric buses into the transportation networks. As a result, there is an urgent need to invest in public charging infrastructure, particularly for fast charging facilities. Consequently, and to complete the portfolio of the green environment, these fast-charging stations (FCSs) are designed using 100% of renewable energy sources (RESs). Thus, this paper proposes an optimization model for the techno-economic assessment of FCSs comprising photovoltaic and wind turbines with various energy storage devices (ESDs). In this regard, the FCS performance is evaluated using flywheels and super capacitors due to their high-power density and charging/discharging cycles and rates. Then, optimal sizing of these distributed generators is attained considering diverse technical and economical key performance indicators. Afterwards, the problem gets more sophisticated by investigating the effect of RES’s uncertainties on the selection criterion of the FCS’s components, design and capacity. Eventually, as an effort dedicated to an online energy management approach, a deep learning methodology based on radial basis network (RBN) is implemented, validated, and carried out. In stark contrast to conventional optimization approaches, RBN demonstrates its superiority by obtaining the optimum solutions in a relatively short amount of time.

Investigating the suitability of pristine and defective C3N monolayer as supercapacitor electrodes: DFT calculations

The possibility of utilizing defected C3N monolayers as the electrodes of supercapacitors (SCs) was investigated in the current study by performing DFT computations. A single-vacancy C3N monolayer (SC3NML), a double-vacancy C3N monolayer (DC3NM) and a pure C3N monolayer (PC3NML) were investigated. The charge plots, quantum capacitance (QC) and the density of state of SC3NML, DC3NM and PC3NML were also studied. Based on the results, the QC of SC3NML and DC3NM at voltages between -0.80 and 0.80 V was more compared to the QC of PC3NML. It was possible to use SC3NML as a negative electrode and DC3NM as a positive electrode, both of which were p-type semi-conductors. The stored charge in the SC3NML and DC3NM was higher compared to the stored charge in PC3NML at voltages 0 to 0.8 V. The charge stored in DC3NM was higher than the stored charge in SC3NML and PC3NML. Finally, DC3NML layer can be regarded as an encouraging electrode for application in SCs.

Optimizing nickel-aluminium layered double hydroxides for supercapacitors: The role of 3D structural assembly

Nickel-aluminium layered double hydroxides (NiAl-LDHs) have emerged as promising electrode materials for supercapacitors (SCs) due to their inherently high specific surface area and theoretical specific capacitance, which are primarily attributed to the rapid pseudocapacitive response at the surface. However, NiAl-LDHs typically form agglomerated nanosheets, leading to a significant reduction in specific surface area, which is crucial for enhancing the number of active sites and improving the capacitive properties of the materials. To overcome this limitation, 2D nanostructures were assembled into 3D architectures by synthesizing NiAl-LDHs with distinct morphologies in a one-step hydrothermal process using an alkaline agent (NH4F). This approach resulted in the formation of 3D NiAl-LDH/HN4F structures, which exhibit a larger contact area and a greater number of redox-active sites. Consequently, the 3D NiAl-LDH/HN4F electrodes demonstrated a significantly higher specific surface area, leading to remarkable improvements in specific capacitance (1219 ± 30F g−1) and energy density (61 ± 1 Wh kg−1) compared to their 2D counterparts. This structural enhancement increases both the surface area and active site density while providing a new framework for designing high-performance LDH-based electrodes.

Enhanced Dynamic Droop Control for Microgrid Frequency and Voltage Stabilization Using Hybrid Energy Storage Systems: A SECANT Method Approach

Due to their variable and intermittent nature, the integration of renewable energy sources poses control challenges related to voltage and frequency stability in isolated microgrids. This paper proposes an enhanced dynamic droop control strategy optimized in active time along with a Hybrid Energy Storage System (HESS) comprising Battery Energy Storage System (BESS), supercapacitors (SUPCA), and Superconducting Magnetic Energy Storage (SMES) to improve microgrid stability. The Dynamic Droop Gains (DDG) are continuously tuned using the rapid-converging SECANT numerical method to enhance transient response and steady-state performance, this was achieved using MATLAB/Simulink. The HESS combines the complementary characteristics of BESS, SUPCA and SMES to balance steady power supply and temporary overload capacity. Detailed simulation studies on a microgrid test system verify that the proposed control strategy significantly enhances voltage/frequency regulation, power sharing accuracy, BESS lifespan and overall stability compared to conventional droop techniques. The SUPCA further improves the transient performance and power quality by mitigating fluctuations. The research demonstrates an innovative way to harness advanced control algorithms and emerging storage technologies for next-generation resilient and sustainable microgrids.

Fabrication of NbTe2@rGO nanosheet by hydrothermal route for cost-effective supercapacitor electrode

The expansion of energy storage devices with extensive stability and high energy density is a crucial area of research that requires immediate attention. In light of these requirements, it was worth noting that supercapacitor (SCs) exhibit great potential as viable options for achieving these demands. Supercapacitor (SCs) despite their potential currently exhibit energy density levels that fall short of the necessary threshold for long-term applications. This limitation primarily stems from the challenge of identifying the ideal materials to enhance their performance. However, transition metal tellurides have a well-studied group of materials that have garnered noticeable consideration because of high energy density. Herein, we present a novel hydrothermal method that involves the fabrication of reduced graphene oxide (rGO) nanosheet combined with niobium telluride (NbTe2) material. However, the NbTe2@rGO nanohybrid's specific capacitance (Csp) was 1475 F g−1, which was approximately twice as high as the specific capacitance of the NbTe2 (667 F g−1) electrode with a specific capacity of 826 C/g at 1 A g−1 which could be ascribed to interconnection between nanoparticles and nanosheets in the NbTe2@rGO nanohybrid with lower Rct = 0.02 Ω and outstanding cycling stability even after undergoing 7000th cycles with a capacitance retention of (97 %). The NbTe2@rGO nanohybrid demonstrated an impressive power density of 285 W kg−1 and energy density of 22 Wh kg−1 at 1 A g−1 in its symmetric two-electrode performance. The findings of this investigation suggested that NbTe2@rGO nanohybrid exhibits promising material for future energy storing devices.

Metallic 1T-MoS2 boosts the kinetics for NiS2-based hybrid supercapacitors with superb rate performance

NiS2 with high theoretical capacitance shows great potential for supercapacitors (SCs). However, the poor cycling stability and sluggish redox kinetics have limited the development of high-rate NiS2-based SCs. Integrating materials with high conductivity potentially reinforces its structure and improves its rate capability. 1T-MoS2 featuring extended interlayer spacing and superior electronic conductivity emerges as an ideal candidate. Therefore, we designed a hybrid material with an alternating interconnected structure of NiS2 and MoS2 with adjustable content of 1T-MoS2. Owing to the improved ion/electron transmittability and the mutual shielding effect, an obvious positive correlation between rate capability and stability with 1T-MoS2 content was established. The optimized 1T-MoS2/NiS2 nanosheets (NMS-2) with 1T phase purity of up to 67.6% in MoS2 demonstrated exceptional specific capacity (579.4 C g−1 at 1 A g−1) and impressive rate capability (345.0 C g−1 at 30 A g−1), which suggests much faster kinetics compared to pure NiS2. Notably, the hybrid supercapacitor (HSC) assembled with NMS-2 as the cathode and activated carbon as the anode (NMS-2//AC HSC) exhibited a maximum specific capacitance of 137.4 F g−1 at 1 A g−1. Furthermore, this HSC can deliver a high energy density of 45.9 Wh kg−1 at 774.9 W kg−1, and could retain 17.7 Wh kg−1 even at a high power density of 7731.7 W kg−1. After 5000 cycles at a high current density of 5 A g−1, the HSC still remained 93.23% of its initial capacitance with an extremely low fading rate of 0.0014% per cycle.