Electrochemical Performance For Supercapacitors Research Articles

Electrochemical performance of asymmetric supercapacitors based on NiCo(OH)4/Cu2(OH)3NO3 electrode

Copper salt metal compounds are widely used in the field of supercapacitor electrode material due to their rich ionic groups. In this paper, NiCo(OH)4/Cu2(OH)3NO3 electrode material is prepared by the solvothermal method by doping NiCo-based hydroxide with copper salt metal compounds (Cu2(OH)3NO3). NiCo(OH)4/Cu2(OH)3NO3 electrode material with different morphologies and sizes is prepared by adjusting the concentration of metal salts. When the metal salt concentration is 2 M, the prepared circular sheet NiCo(OH)4/Cu2(OH)3NO3 electrode material with a diameter of 3 μm and a thickness of 150 nm exhibits excellent specific capacitance (1335 C g−1 at 1 A g−1) and capacitance retention (after 5000 cycles, the capacitance retention rate is 71.7 %). Furthermore, the NiCo(OH)4/Cu2(OH)3NO3//AC asymmetric supercapacitor is prepared, which exhibited an energy density is 83.78 Wh kg−1 at a power density of 800 W kg−1. The capacitance retention rate of the asymmetric supercapacitor is 65.2 % (after 5000 cycles at 10 A g−1). We used copper salt metal compounds (Cu2(OH)3NO3) to improve the electrochemical performance of NiCo-based hydroxide electrode material. This idea has certain reference significance for improving the performance of NiCo-based hydroxide electrode material.

Enhancing the electrochemical performance of hybrid supercapacitors with in-situ grown ultrasound-mediated heterostructure bi-metallic and dual-linker MOF nanoarchitecture by harnessing charge storage mechanisms

In the present technological era, energy storage devices like batteries and supercapacitors hold immense importance, and their hybrid variants have gained notable interest. The aim of this study was to develop a dual-linker MOF capable of selectively capturing cobalt and vanadium ions using two distinct organic ligands. The ultrasonication-assisted hydrothermal technique was demonstrated to be a resounding success in achieving the synthesis of the bimetallic and dual-linker metal-organic framework (MOF). The outcome of the electrochemical analysis demonstrated that the Co-V-capacitance MOF contributes to the battery-type process by diffusion control at 88.52 %, while 11.48 % of the process is capacitive-controlled, in an aqueous electrolyte (1 M KOH). Additionally, the upgraded Co-V-MOF electrode displayed an impressive specific capacity of 1711.1 F/g. The utilization of Co-V-MOF in the hybrid Asymmetric supercapacitor resulted in an outstanding specific capacitance of 187.5 F/g, with energy and power densities of 70.65 Wh/kg and 835 W/kg, respectively. It is important to mention that the Co-V-MOF hybrid supercapacitor exhibited excellent and consistent performance for 10,000 cycles (92.21 %). The outstanding specific capacitance performances produced in this study represent the most significant findings reported to date for bi-metallic and dual-linker MOFs based on vanadium-cobalt.

Construction of 3D N-doped Ti3C2/TiO2 hollow sphere structure with superior electrochemical performance for supercapacitor

Herein, the 3D N-doped Ti3C2/TiO2 sphere structure is constructed via an innovative three-step method including the preparation of 3D Ti3C2 microspheres with PMMA as templates, the situ-growth of TiO2 nanoparticles on Ti3C2 and the subsequent annealing treatment in NH3. N element is doped in composite after annealing in NH3 to improve the transfer rate of ions and electrons, and N-doped Ti3C2/TiO2 hollow composite provides an abundant active surface for the sufficient contact between electrodes and electrolytes to enhance charge transport and electrolyte diffusion. Benefiting the unique structure feature and the synergistic effects of active materials, the N-doped Ti3C2/TiO2 electrode exhibits a high specific capacitance of 572 F g−1 at a current density of 1 A g−1 and a superior cyclic stability of 99.6% of its initial value for 9500 cycles at 10 A g−1. Based on this, a symmetric supercapacitor (SSC) based on N-doped Ti3C2/TiO2 electrode is further assembled. The SSC shows a competitive capacitance of 157 F g−1 at 1 A g−1. More importantly, the comparable energy density of 17.7 Wh kg−1 is achieved at the power density of 450 W kg−1. This work will give promising guidance for designing and fabricating the durable electrodes with excellent electrochemical behavior for practical application in future.

CoSe2@ZnS microsphere arrays with remarkable electrochemical performance for hybrid asymmetric supercapacitor

This study presents a simple hydrothermal synthesis method for preparing CoSe2, ZnS, and their nanohybrid combinations (ZnS-70 % CoSe2 and ZnS-50 % CoSe2, referred to as ZC-1 and ZC-2) for the first time. These materials are intended for application in a supercapacitor (SC) and are synthesized through an ex-situ wet-chemical approach. The research thoroughly examines the electrochemical properties of as-prepared electrodes and how they relate to their structure and morphology to understand their charge storage mechanism better. The detailed characterization reveals that a one-step hydrothermal reaction obtains the cubic crystal structure of the ZnS with microsphere morphology, and the CoSe2 presents a snow crystals-like morphology with a highly smooth and transparent surface appearance. The systematic electrochemical examination declares the typical pseudocapacitive charge storage response owing to fast Faradaic redox reactions with good reversibility and rate capability. Notably, a high capacitance of CoSe2-ZnS nanohybrid (denoted as ZC-2) is realized by the synergistic effect between ZnS and CoSe2 supported by the impedance, cyclic voltammetry, and charge/discharge studies. High specific energy with a power of 46.71 Wh/kg (899.21 W/kg) and 9 Wh/kg (5400 W/kg) is realized by adding an optimal voltage and capacitance simultaneously by fabricating a hybrid asymmetric HASCs (ZC-2||AC HASC) in aqueous solution. This study believes that metal sulfide and selenide-based nanohybrids can be effective candidates for competing in the growing electrochemical energy storage demand.

High-performance supercapacitors enabled by N/S dual-doped porous carbon and DMO-regulated electrolyte

The demand for high-performance supercapacitors exceeds the capabilities of pristine carbon materials and traditional electrolytes. To address this gap, we prepared a petal-like multicyclic polycondensate precursor (PCDP) using Knoevenagel reaction and amine/aldehyde condensation between 3-aminorhodanine and p-phthalaldehyde. The subsequent activation of PCDP by KOH and carbonization at various temperatures (600–900 °C) were employed to produce N/S-dual doped porous carbon (N/S-DDPCs) for use as electrode materials. For N/S-DDPC8 carbonized at 800 °C, the specific surface area measured as the highest at 2047 m2 g−1 with a significant number of interconnected micro/mesoporous structures and higher N and S contents of 3.57 % and 2.31 %, respectively. Furthermore, Zn(CF3SO3)2 aqueous electrolyte was developed using dimethyl oxalate (DMO) to regulate and improve the electrochemical performance of the N/S-DDPCs while also providing better stability. In comparison to the conventional Zn(CF3SO3)2 electrolyte, the utilization of N/S-DDPC8 in DMO-regulated Zn(CF3SO3)2 electrolyte resulted in a noteworthy enhancement in energy density and power density, soaring to 36.4 Wh kg−1 from 11.7 Wh kg−1 and to 642 W kg−1 from 250 W kg−1 at a current density of 0.5 A g−1, respectively. It is particularly noteworthy that N/S-DDPC8-DMO-D can maintain 100 % specific capacitance even after 10,000 cycles, demonstrating its high-level electrochemical consistency. In brief, the porous N/S-DDPCs and DMO-regulated electrolyte created in this study serve as a valuable guide for boosting the electrochemical performance of supercapacitors.

Design of multifunctional 1D/2D polypyrrole nanotubes@pg-C3N4 binary nanocomposite for removal of mercury (Hg2+) from wastewater and supercapacitor applications

A multifunctional, highly efficient, 1D/2D Polypyrrole nanotubes@pg-C3N4 binary nanocomposite was prepared using a one-pot ultra-sonication approach. The influence of 1D and 2D nanomaterials on the behavior of developed PPy-NTs-based nanocomposite for eliminating Hg2+ ions was explored. The developed nanocomposite revealed greater adsorption performance to eliminate Hg2+ions from contaminated water. The PPy-NTs/pg-C3N4 potential as an excellent sorbent for the removal of Hg2+ and possible mechanisms were assessed using batch experiments involving multiple factors that can also optimize the maximum adsorption conditions that were found to be at pH = 5, 1 h stirring time, and 0.5 g/L adsorbent dosage. The maximum Hg2+ absorption capacity reached was 197 mg/g. The data were well fitted with the pseudo-second-order kinetic model, which indicates that the chemisorption process controls the Hg2+ ions adsorption onto the pg-C3N4/PPy-NTs. The four adsorption isotherms models were applied to analyze the adsorption of Hg2+ ions on the developed adsorbent. The data were well described with Freundlich isotherm, revealing the presence of heterogeneous adsorption sites. The effect of temperature and thermodynamic considerations were investigated, showing that Hg2+ ion adsorption is endothermic. Additionally, the prepared material was explored for the supercapacitor application. It delivered an outstanding electrochemical supercapacitor performance and remarkable cycling stability.

Integrating V-doped CoP on Ti3C2Tx MXene-incorporated hollow carbon nanofibers as a freestanding positrode and MOF-derived carbon nanotube negatrode for flexible supercapacitors

Novel architectural electrode materials that are freestanding and exhibit improved electrochemical performances in flexible asymmetric supercapacitors are urgently needed; however, designing these materials is challenging. Herein, a Ti3C2TX MXene-aligned hollow carbon fiber (MX/HCF) is engineered and vanadium-doped cobalt phosphide nanorod arrays are grown on it (V-CoP@MX/HCF) and applied for supercapacitor positrode. V doping modulates the surface structure and electronic environment of CoP nanorods grown over conductive and flexible MX/HCFs. As expected, the optimized V-CoP@MX/HCF exhibits a better electrochemical performance (1896.8Fg−1) than that of CoP@MX/HCF and CoP@HCF. For the negative electrode, zeolitic imidazolate framework-67 (ZIF-67) grown on electrospun polyacrylonitrile (PAN) fibers is converted to cobalt nanoparticle-encapsulated nitrogen-doped carbon nanotubes at carbon nanofibers (Co-CNT@CNF) by a simple heat treatment without the burden of external catalysts and reducing gases. The as-designed freestanding Co-CNT@CNF delivers a specific capacitance of 405.5Fg−1 with superior cycling stability. A flexible asymmetric supercapacitor (V-CoP@MX/HCF//Co-CNT@CNF) is designed that unveil remarkable electrochemical properties, such as a high energy density of 72.4 Wh kg−1 at 800.12 W kg−1 and good capacitance retention (91.4 %) after 10,000 charge/discharge cycles. Furthermore, the device can maintain a consistent performance regardless of the bending degree. More importantly, this work provides new opportunities to rationally design novel freestanding cathodes and anodes for high-performance flexible asymmetric supercapacitors.

Ammonium and Tartrate Salts as Alternatives to Neutral Aqueous Electrolytes for Supercapacitors

AbstractSupercapacitors are promising energy storage devices in terms of power density and lifetime. Organic electrolytes are frequently applied in commercial supercapacitor devices. However, their water‐based counterparts are much safer, more sustainable and cost‐effective. In this study we therefore present, for the first time, aqueous tartrate‐based electrolytes (sodium tartrate / ammonium tartrate) for supercapacitor applications, and relate them to well‐known inorganic aqueous electrolytes like Na2SO4. Additionally, the influence of the cation on the electrochemical performance of supercapacitors is investigated using sodium and ammonium cations for comparison. We demonstrate the electrochemical performance and physicochemical properties of ammonium tartrate / sulfate and sodium tartrate / sulfate. An improvement of the conductivity in the range of 40–60 % was achieved by the exchange of sodium cation with ammonium cation. Carbon electrodes in newly introduced aqueous tartrate‐based electrolytes deliver high specific capacitances up to 117 Fg−1. Furthermore, electrical double layer capacitors (EDLCs) containing 1 M ammonium tartrate display a high energy density at 0.1 Ag−1 and at 10 Ag−1 (9.88 Whkg−1 and 1.14 Whkg−1, respectively). Floating tests show excellent long‐term performance. Tartrate‐based EDLCs retain >80 % of their initial capacitance at 1.6 V cell voltage (120 h floating time). In the case of ammonium tartrate electrolyte, a novel metal‐free and non‐toxic concept for an eco‐friendly supercapacitor device is proposed.

Polyaniline nanosheets templated from aniline‒acid precipitates and their electrochemical performance for flexible supercapacitor

The simple synthesis of two-dimensional (2D) polyaniline (PANI) structures remains a big challenge owing to the intrinsic growth of PANI chains into one-dimensional structures and the curling of the PANI chains into spherical particles. In this contribution, we report on the simple synthesis of PANI nanosheets by oxidizing aniline–acid precipitates with ammonium persulfate (APS) through a chemical oxidation polymerization method. The tested acids include methylene disulfonic acid, sulfuric acid, benzoic acid, oxalic acid, p-toluenesulfonic acid, hydrochloric acid, and acetic acid. The aniline–acid precipitates serve as separation-free templates for producing PANI nanosheets. The yield, oxidation level, electronic conductivity, conjugation length, and thickness of the PANI nanosheets can be tuned by controlling the molar ratio of aniline/APS. The electrochemical performance of PANI nanosheets-based symmetric supercapacitors was examined at the temperature ranging from room temperature to –60 °C. The PANI nanosheets with relatively high specific surface area rather than the oxidation level manifest superior electrochemical performance.

Boosting the electrochemical performance of NiFe2O4/Carbon composite materials by nitrogen doping for supercapacitors application

The development of high-performance anode materials is of great importance for improving the electrochemical performance of asymmetric supercapacitors. Here, nickel ferrite/porous carbon composite is synthesized via hydrothermal approach and the electrochemical properties are improved by nitrogen doping process. As the surface nitrogen content of the porous carbon precursor increased from 2.40 at.% to 9.53 at.%, the nickel ferrite/porous carbon composite exhibited substantial improvement in specific capacitance (increased from 136.4 to 201.4 F g−1 at 1 A g−1) in an alkaline aqueous electrolyte. The energy density of the assembled asymmetric supercapacitor was increased from 17.7 W h kg−1 to 11.2 W h kg−1, and the cycle retention rate after 10,000 cycles at 2 A g−1 was increased from 16.5 % to 85.7 %. Nitrogen atoms on the carbon surface provide active sites for the growth of nickel ferrite nanoparticles and enhance the interfacial effect between nickel ferrite nanoparticles and porous carbon materials, enhancing the charge transfer and preventing particle aggregation during charge and discharge processes. The fabricated nickel ferrite/nitrogen-doped porous carbon composite exhibits excellent capacitance and cycling stability, providing a new option for asymmetric supercapacitor anode materials.

Controlled synthesis of sulfur-vacancy-enriched sheet-like Ni3S2@ZnS composites for asymmetric supercapacitors with ultralong cycle life

To improve the electrochemical performance of supercapacitors, pseudocapacitive electrode materials must be synthesized with high surface activity, high electrical conductivity, and ultralong cycle life, which presents a significant challenge. In this study, we reported on the synthesis of sulfur-vacancy-enriched sheet-like Ni3S2 @ZnS composites based on 3D network porous nickel foam (NF) using a two-step electrodeposition protocol. The Ni3S2 @ZnS/NF exhibited a specific capacitance of 1141.9 C g−1 (241.0 mC cm−2) at a current density of 19 A g−1 (5 mA cm−2). The Ni3S2 @ZnS/NF positive electrode was used to fabricate an all-solid asymmetric supercapacitor, which demonstrated an ultrahigh energy density of 12.0 μWh cm−2 at a power density of 7.2 mW cm−2, as well as an ultrahigh capacitance retention rate of 86.7% after 50,000 cycles. Experimental and theoretical results indicated that the introduction of sulfur vacancies could improve the surface activity of the electrode, as well as its hydroxide diffusion and adsorption ability by adjusting the surrounding local electron concentration of cations around them. This accelerated the interfacial redox reaction and resulted in remarkable electrochemical performance for the Ni3S2 @ZnS/NF electrode. This research provides a pathway for the controlled synthesis of 2D nanosheets with vacancy-rich structures and their potential electrochemical applications.

The role of nitrogen-doping on the electrochemical behavior of MOF-derived carbons in ionic liquid electrolytes

Metal-organic frameworks (MOFs) derived nanoporous carbons have been intensively studied as electrode materials for electric double-layer capacitors. However, the current research on MOF-derived carbons were mainly focused on investigating electrochemical performances of supercapacitors in aqueous electrolytes, and there were only a few studies involved ionic liquids electrolytes. In addition, the research of nitrogen doping effect on MOF-derived carbons in ionic liquids electrolytes has rarely been reported. Nitrogen doping is considered to be the common and effective way to improve the electrochemical performances of carbonaceous electrodes because it can not only enhance the electrical conductivity but also bring about pseudocapacitances in aqueous electrolytes. However, the nitrogen doping effect in ionic liquids electrolytes need to be further investigated especially for MOF-derived carbons with large quantities of micropores. In this study, MOF-derived nitrogen-doped carbons were synthesized by carbonization of urea functionalized Zn-MOF-74, and their electrochemical behavior in EMIMBF4 and EMIMTFSI ionic liquid electrolytes were investigated. The nitrogen-doping degree was tuned by adjusting the amount of urea. Electrochemical test showed that nitrogen-doped carbons exhibited a maximum capacitance enhancement of 24.4 % than pristine sample in ionic liquid electrolytes. Nevertheless, nitrogen-doping contributed few pseudocapacitances in ionic liquid electrolytes, and the enhanced electrochemical performances could be ascribed to the increased electrical conductivity and the matched pore structures.

Nickel-cobalt phosphide interfacial heterostructures as supercapacitor electrode material for electrochemical energy storage application

Transition metal phosphides have become one of the excellent electrode material choices for improving the electrochemical performance of supercapacitors due to their high theoretical capacity and good redox ability. The introduction of secondary metals in single metal phosphides can enhance the properties and chemical stability of their redox sites. Combining multiple types of transition metal phosphides can comprehensively utilize the properties of each component and improve the charge efficiency at the interface, thus exhibiting good electrochemical performance. Therefore, in this work, nickel–cobalt phosphide heterojunction Co2P/NiCoP/Ni2P was prepared. At the current density of 1 A/g, the specific capacitance of the Co2P/NiCoP/Ni2P electrode material is 174.2 mAh/g. And its specific capacitance is higher than each of its components at any current density. An asymmetric supercapacitor was assembled with Co2P/NiCoP/Ni2P as the positive electrode and activated carbon as the negative electrode. When the power density is 800 W kg−1, the device can exhibit an energy density of 42.29 W h kg−1, which shows a high energy density while maintaining the power density. At the current density of 2 A/g, the assembled supercapacitor could still maintain 90% of the initial specific capacitance after 10,000 cycles, showing high cycle stability. This provides ideas for future research on this type of energy storage materials.

3D heterostructure constructed by few-layer 1T MoS2 and MXene under high electrostatic fields for high-performance supercapacitors

Electrostatic spray deposition (ESD) is a promising technique for preparing high-quality heterostructure materials to achieve high electrochemical performance. Moreover, the materials obtained by ESD possesses well-dispersed, bonder-free and easy-control advantages. Herein, we firstly report that 1T MoS2/Ti3C2Tx heterostructure material is successfully constructed by few-layer 1T MoS2 and Ti3C2Tx MXene through ESD. The construction of heterostructure by high electrostatic fields is able to solve problem of agglomeration of layered materials, improve conductivity and stabilize 1T MoS2 to realize outstanding electrochemical performance of supercapacitor. As expected, the binder-free 1T MoS2/Ti3C2Tx heterostructure displays an excellent specific capacitance (1198 mF cm−2 at 3 mA cm−2), a high rate performance (45% as current density from 3 to 20 mA cm−2) and long-cycle life (73.8% capacity retention after 7000 cycles at 20 mA cm−2). More interestingly, a simple and efficient route to prepare 2D/2D heterostructure electrode for storing energy can be extended to other materials.

The influence of electrode geometry on the electrochemical performance of fabric-based screen-printed coplanar supercapacitors

Coplanar supercapacitors are promising flexible energy storage systems due to the excellent flexibility and tailored shapes and sizes of electrodes. However, the influence mechanism of electrode’ geometry parameter on the electrochemical performance of the flexible coplanar supercapacitors needs to be elucidated to realize the performance enhancement. Herein, the flexible coplanar supercapacitors with different thicknesses, widths and lengths of screen-printed electrodes were constructed on the cotton fabric substrates utilizing multi-walled carbon nanotubes ink and polymer gel electrolytes. The relationship between electrodes' geometry and overall electrochemical performance of flexible coplanar supercapacitors was detailed analyzed and demonstrated by employing equivalent series circuit model and electrode kinetic theory. Furthermore, due to the favorable aspect ratio and relatively low electrode and electrolyte resistance, the fabric-based coplanar supercapacitor with electrode size of 4 × 10 mm shows optimal electrochemical performance with areal capacitance of 3.08 mF cm−2 at 20 mV s−1, fast electrode response and effective kinetic process. Most importantly, the fabric-based supercapacitor exhibits excellent flexibility and cycling performance with capacitance retention rate over 79.6 % after 4000 charge and discharge cycles, indicating application potential in wearable electronic devices. The analysis and assessments of electrodes' geometry provides theoretical reference for the electrode design and optimization of flexible coplanar supercapacitors.

Inorganic perovskite photo-assisted supercapacitor for single device energy harvesting and storage applications

Halide-perovskite having excellent electronic, ionic, optoelectronic and optoionic properties have been found suitable for both energy harvesting and energy storage devices. Herein, we exploit these properties to fabricate a photo-assisted supercapacitor serving the dual functions of energy harvesting and electrochemical energy storage in a single device. The device utilized stable inorganic Cu3Bi2I9 perovskite material in fabricating a Cu-perovskite photoactive electrode. A novel HPvA gel electrolyte was synthesized and sandwiched between two Cu-perovskite photoactive electrodes, to obtain a Cu-perovskite photo-assisted supercapacitor. The HPvA gel electrolyte was characterized by fourier-transfrom infrared spectroscopy (FTIR), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The Cu-perovskite photoactive electrode was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). We characterized the electrochemical and photo-electrochemical energy storage performance of the Cu-perovskite photo-assisted supercapacitor by cyclic voltammetry (CV) and EIS. The device recorded 127 % energy density augmentation, at a scan rate of 0.01 V/s. The Cu-perovskite photo-assisted supercapacitor retained 93.8 % of its initial capacitance, after 10,000 charge-discharge cycles.

Three-dimensional Salacca zalacca shell-derived oxygen-doped porous carbon framework and its electrochemical performance in supercapacitors

Three-dimensional Salacca zalacca shell-derived oxygen-doped porous carbon framework and its electrochemical performance in supercapacitors

Germanium‐Functionalized 3D Microporous, Nanostructured Nickel–Nickel Oxides for Application in Asymmetric Supercapacitors

Supercapacitors and batteries are essential for sustainable energy development. However, the bottleneck is the associated high cost, which limits bulk use of batteries and supercapacitors. In this context, realizing that the cost of energy‐storage device mainly depends on materials, synthesis processes/procedures, and device fabrication, an effort is made to rationally design and develop novel low‐cost electrode materials with enhanced electrochemical performance in asymmetric supercapacitors. Herein, surface functionalization approach is adopted to design low‐cost 3D mesoporous and nanostructured nickel–nickel oxide electrode materials using facile synthesis for application in supercapacitors. It is demonstrated that the 3D mesoporous Ni provides the high surface area and enhanced ionic conductivity, while germanium functionalization improves the electrical conductivity and reduces the charge‐transfer resistance of NiO. Surface functionalization with Ge demonstrates the significant improvement in specific capacitance of NiO. The asymmetric supercapacitor using these Ge‐functionalized NiO–Ni electrodes provides a specific capacitance of 304 Fg−1 (94 mF cm−2), energy density of 23.8 Wh kg−1 (7.35 μWh cm−2), and power density of 6.8 kW kg−1 (2.1 mW cm−2) with excellent cyclic stability of 92% after 10 000 cycles. To validate their practical applications, powering the digital watch using the asymmetric supercapacitors in laboratory conditions is demonstrated.

Construction of high-performance solid-state asymmetric supercapacitor based on Ti3C2Tx MXene/CuS positive electrode and Fe2O3@rGO negative electrode

The reasonable and logical construction of electrode materials along with greater electrochemical features and solid architectural design is an effective strategy for boosting the electrochemical performance of supercapacitors. In this paper, Ti3C2Tx MXene/CuS composites have been synthesized using an electrostatic attraction connection of negatively charged 2D few-layered Ti3C2Tx MXene sheets with positively charged CuS nanoparticles and are investigated as an asymmetric supercapacitor active material. The addition of MXene enhances the conductivity and specific surface area of the MXene/CuS electrode compared to their individual components. The as-prepared MXene/CuS electrode exhibits a high specific capacity (1541.6C g−1 (2569.3 F g−1)) at 1 A g−1 and an excellent cycle performance with 93.5 % capacity retention after 10,000 cycles. Furthermore, Fe2O3 nanoparticles/reduced graphene oxide (rGO) nanosheets (Fe2O3@rGO) composite electrode is also produced. The designed Fe2O3@rGO negative electrode with a wide operation voltage window of 1.1 V can deliver a capacity of 255.6C g−1 at 1 A g−1. Ultimately, the MXene/CuS//Fe2O3@rGO device displays energy density of 74.1 Wh kg−1 and power density of 849.8 W kg−1. In addition, the ASC shows excellent cycling stability of 91.3 % capacity retention after 10,000 cycles.

Morphology induced symmetrical supercapacitive performance of the 3D interconnected Ni(OH)2 framework

The rational design of electrode materials for energy storage applications is a key element of resolving the energy crisis. Herein, nickel hydroxide (NHO) nanostructures with different morphologies, such as platelet (Platelets-NHO), three-dimensional flower (3DF-NHO), and flake-like (Flakes-NHO) morphologies, were synthesized using different solvents inside the hydrothermal reactor during the reaction process. The fabricated electrode materials of the NHO nanostructure were further characterized using different types of microscopic and spectroscopic techniques, and their electrochemical performance was further studied in a three-electrode assembly cell to explore the morphological effect on the supercapacitive performance. The 3DF-NHO displayed a significantly enhanced capacitance value (1112.5 F g−1) than Platelets-NHO (820.0 F g−1) and Flakes-NHO (850.0 F g−1) at the same current load (1 A g−1). The electrochemical supercapacitive performance of 3DF-NHO, Platelet-NHO, and Flakes-NHO revealed that the morphology played an important role in enhancing the electrode chemical performance of the electrode material. The symmetric assembly cell of 3DF-NHO was also assembled, and cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and cyclic stability tests were recorded, revealing excellent performance for potential applications in the field of energy storage devices. Among the materials, the excellent performance of 3DF-NHO is credited to the three-dimensional structures and interconnected petals, which provide a better surface and suitable space for the electrolytes during the electrochemical reaction. These results suggest that the rational design of the electrode material using an appropriate solvent could help to fabricate a large number of different morphologies of NHO, which may be a potential candidate for energy storage electrode materials.