Desert rose like heterostructure of NiCo2O4/NF@PPy composite has high stability and excellent electrochemical performance for asymmetric super capacitor application

A chromium cobaltite based ternary composite as an efficient electrode material for hybrid supercapacitors with theoretical investigation

To cater to the growing demand for advanced energy storage devices, the development of efficient electrode materials with brilliant electrochemical response is highly required. Battery-like materials have gained wide research attention as effective electrode materials for hybrid supercapacitors (HSCs). In this account, chromium cobaltite (CrCo2O4) has been synthesized via a facile hydrothermal route. The structural and electronic properties of CrCo2O4 have been investigated using DFT. Activated carbon (AC) and polypyrrole (PPY) have been introduced to hybridize with CrCo2O4 to enhance its electrochemical performance. The high conductivity of PPY, along with the high surface area and excellent cycling stability of AC, synergistically boosts the performance of CrCo2O4. The ternary composite CrCo2O4/AC/PPY exhibited a higher capacitance of 991.25 F g-1 than the pristine CrCo2O4 (301.53 F g-1) at 5 mV s-1. The composite also displayed high cycling stability with 84.25% capacitive retention after ten thousand cycles. The composite also delivered a lower charge transfer resistance (0.36 Ω), which resulted in better charge transfer. A HSC with CrCo2O4/AC/PPY as the positive electrode and MnO2/AC as the negative electrode was fabricated that delivered a high energy density of 97.77 W h kg-1 and power of 1.6 kW kg-1. A high capacitive retention of 76.75% was observed for ten thousand cycles. The practicality of the prepared material was tested by connecting three hybrid cells in series to illuminate a panel of 57 LEDs. The panel was able to glow for 51 minutes. The outstanding performance of the composite reveals the excellent possibility for application in high-performance advanced hybrid SCs.

One-pot hydrothermal synthesis of 3D garland BiOI, spherical ZnO, and CNFs onto Ni foam: Supercapacitor performance with enhanced electrochemical properties

This study reported one-pot hydrothermal synthesis of 3D garland BiOI, spherical ZnO, and carbon nanofibers (CNFs) onto Ni foam substrate with improved supercapacitor performance and enhanced electrochemical properties. The synthesized nanocomposites exhibited high specific capacitance (SC) of 1073 g-1 at a current density of 1 A/g and excellent cycling stability with 88.6% retention of original capacity after 5000 cycles in 2M KOH aqueous solution. The findings highlight the potential of 3D materials for use as electrode materials in advanced supercapacitor applications due to their high energy storage capabilities.

Polypyrrole and activated carbon enriched MnCo2O4 ternary composite as efficient electrode material for hybrid supercapacitors

The development of proficient electrode materials is one of the major tasks faced by modern techniques for energy storage. Integrating different materials with synergistic effects can be a valuable strategy for designing storage devices with high capacity and energy density. The spinel manganese cobaltite (MnCo2O4) is an outstanding candidate for supercapacitors owing to its remarkable pseudocapacitive behavior. However, it suffers from low electric conductivity and limited cyclic stability. To overcome its limitations, activated carbon with superior cyclic stability and polypyrrole with high electric conductivity can be incorporated in MnCo2O4. The synergistic effect of these components offers high capacitance, better conductivity, and superior cyclic performance to the ternary composite. Herein, the MnCo2O4/AC/PPY ternary composite has been synthesized by a facile approach. The optimized ternary composite (MAP-20) exhibited a wonderful capacitance of 945.77 F g-1 at five mV s-1 compared to pristine MnCo2O4 (254.98 F g-1). The real-time applicability of the optimized composite was tested with asymmetric device configuration. The asymmetric device with MAP-20 and MnO2/AC electrodes exhibited a wonderful Ed of 88.12 W h kg-1 (Pd ∼ 1.6 kW kg-1). The asymmetric device also exhibited excellent cyclic performance of 89.68% for 10 000 cycles. Further, the real-time applicability of the device was tested by illuminating a 39 red LED panel. Three asymmetric cells connected in series illuminated the panel for about 45 minutes. All these results suggest that the synergistic integration of various efficient electrode materials leads to enhanced electrochemical performance of supercapacitors.

Enhanced performance of hybrid supercapacitors by the synergistic effect of Co(OH)2 nanosheets and NiMn layered hydroxides

A self-supporting composite electrode material with a unique three-dimensional structure was synthesized by in-situ growth of nanoscale NiMnLDH-Co(OH)₂ on a nickel foam substrate via hydrothermal electrodeposition. The 3D layer of NiMnLDH-Co(OH)₂ provided abundant reactive sites for electrochemical reactions, ensuring a solid and conductive skeleton for charge transfer and resulting in significant enhancement of electrochemical performance. The composite material showed a strong synergistic effect between the small nano-sheet Co(OH)₂ and NiMnLDH, which promoted reaction kinetics, while the nickel foam substrate acted as a structural conductivity agent, stabilizer, and good conductive medium. The composite electrode showed impressive electrochemical performance, achieving a specific capacitance of 1870F g^-1 at 1 A g^-1 and retaining 87% capacitance after 3000 charge-discharge cycles, even at a high current density of 10 A g^-1. Moreover, the resulting NiMnLDH-Co(OH)₂//AC asymmetric supercapacitor (ASC) demonstrated remarkable specific energy of 58.2 Wh kg^-1 at a specific power of 1200 W kg^-1, along with outstanding cycle stability (89% capacitance retention after 5000 cycles at 10 A g^-1). More importantly, DFT calculations reveal that NiMnLDH-Co(OH)₂ facilitates charge transfer, accelerating surface redox reactions and increasing specific capacitance. This study presents a promising approach towards designing and developing advanced electrode materials for high-performance supercapacitors.

Facile Synthesis of NiCo2O4 Nanowire Arrays/Few-Layered Ti3C2-MXene Composite as Binder-Free Electrode for High-Performance Supercapacitors

Herein, a 3D hierarchical structure is constructed by growing NiCo₂O₄ nanowires on few-layer Ti₃C₂ nanosheets using Ni foam (NF) as substrate via simple vacuum filtration and solvothermal treatment. Ti₃C₂ nanosheets are directly anchored on NF surface without binders or surfactants, and NiCo₂O₄ nanowires composed of about 15 nm nanoparticles uniformly grow on Ti₃C₂/NF skeleton, which can provide abundant active sites and ion diffusion pathways for enhancing electrochemical performance. Benefiting from the unique structure feature and the synergistic effects of active materials, NiCo₂O₄/Ti₃C₂ exhibits a high specific capacitance of 2468 F g^-1 at a current density of 0.5 A g^-1 and a good rate performance. Based on this, an asymmetric supercapacitor (ASC) based on NiCo₂O₄/Ti₃C₂ as positive electrode and activated carbon (AC)/NF as negative electrode is assembled. The ASC achieves a high specific capacitance of 253 F g^-1 at 1 A g^-1 along with 91.5% retention over 10,000 cycles at 15 A g^-1. Furthermore, the ACS presents an outstanding energy density of 90 Wh kg^-1 at the power density of 2880 W kg^-1. This work provides promising guidance for the fabrication of binder-free, free-standing and hierarchical composites for energy storage application.

Facile Synthesis of CoSe/Co3O4-CNTs/NF Composite Electrode for High-Performance Asymmetric Supercapacitor

Electrode materials are key factors for supercapacitors to endow them with excellent electrochemical properties. Here, a novel hybrid structure of a CoSe/Co₃O₄-CNTs binder free composite electrode on nickel foam was prepared via a facile flame method, followed by an electrodeposition process. Benefitting from the synergetic effects of the multicomponent (with low resistances of 1.542 Ω cm² and a moderate mesoporous size of 3.12 nm) and the enlarged specific surface area of the composite material (77.4 m² g^-1), the CoSe/Co₃O₄-CNTs composite electrode delivers a high specific capacitance of 2906 F g^-1 at 5 mV s^-1 with an excellent rate stability. The fabricated CoSe/Co3O4-CNTs/NF//AC ASC exhibits a high energy density of 43.4 Wh kg^-1 at 0.8 kW kg^-1 and a long cycle life (92.7% capacitance retention after 10,000 cycles).

Facile Electrodeposition of NiCo2O4 Nanosheets on Porous Carbonized Wood for Wood-Derived Asymmetric Supercapacitors

Multichannel-porous carbon derived from wood can serve as a conductive substrate for fast charge transfer and ion diffusion, supporting the high-theory capacitance of pseudocapacitive materials. Herein, NiCo₂O₄ nanosheets, which are hierarchically porous, anchored on the surface of carbonized wood via electrodeposition for free-binder high-performance supercapacitor electrode materials, were proposed. Benefiting from the effectively alleviated NiCo₂O₄ nanosheets accumulation and sufficient active surface area for redox reaction, a N-doped wood-derived porous carbon-NiCo₂O₄ nanosheet hybrid material (NCNS–NCW) electrode exhibited a specific electric capacity of 1730 F g⁻¹ at 1 A g⁻¹ in 1 mol L⁻¹ KOH and splendid electrochemical firmness with 80% capacitance retention after cycles. Furthermore, an all-wood-based asymmetric supercapacitor based on NCNS–NCW//NCW was assembled and a high energy density of 56.1 Wh kg⁻¹ at a watt density of 349 W kg⁻¹ was achieved. Due to the great electrochemical performance of NCNS–NCW, we expect it to be used as an electrode material with great promise for energy storage equipment.

Nickel Cobaltite: A Positive Electrode Material for Hybrid Supercapacitors

The increased demand of energy due to the recent technological advances in diverse fields such as portable electronics and electric vehicles is often hindered by the poor capability of energy-storage systems. Although supercapacitors (SCs) exhibit higher power density than state-of-the art batteries, their insufficient energy density remains a major challenge. An emerging concept of hybrid supercapacitors (HSCs) with the combination of one capacitive and one battery electrode in a single cell holds a great promise to deliver high energy density without sacrificing power density and cycling stability. This Minireview elaborates the recent advances of use of nickel cobaltite (NiCo₂ O₄ ) as a potential positive electrode (battery-like) for HSCs. A brief introduction on the structural benefits and charge storage mechanisms of NiCo₂ O₄ was provided. It further shed a light on composites of NiCo₂ O₄ with different materials like carbon, polymers, metal oxides, and others, which altogether helps in increasing the electrochemical performance of HSCs. Finally, the key scientific challenges and perspectives on building high-performance HSCs for future-generation applications were reviewed.

A review of π-conjugated polymer-based nanocomposites for metal-ion batteries and supercapacitors

Owing to their extraordinary properties of π-conjugated polymers (π-CPs), such as light weight, structural versatility, ease of synthesis and environmentally friendly nature, they have attracted considerable attention as electrode material for metal-ion batteries (MIBs) and supercapacitors (SCPs). Recently, researchers have focused on developing nanostructured π-CPs and their composites with metal oxides and carbon-based materials to enhance the energy density and capacitive performance of MIBs and SCPs. Also, the researchers recently demonstrated various novel strategies to combine high electrical conductivity and high redox activity of different π-CPs. To reflect this fact, the present review investigates the current advancements in the synthesis of nanostructured π-CPs and their composites. Further, this review explores the recent development in different methods for the fabrication and design of π-CPs electrodes for MIBs and SCPs. In review, finally, the future prospects and challenges of π-CPs as an electrode materials for strategies for MIBs and SCPs are also presented.

Facile Synthesis of Coral Reef-Like ZnO/CoS2 Nanostructure on Nickel Foam as an Advanced Electrode Material for High-Performance Supercapacitors

Nanocomposite electrodes receive much attention because of their excellent energy storage nature. Electrodes for supercapacitors have come a major source of interest. In this pursuit, the current work elucidates binder-free coral reefs resembling ZnO/CoS2 nanoarchitectures synthesized on the surface of Ni foams employing the cost-effective hydrothermal route. The Zno/CoS2 nanocomposite demonstrated excellent battery-type behavior, which can be employed for supercapcitor application. Various analyses were carried out in the current study, such as X-ray diffraction and high-resolution scanning electron microscopy, which allowed defining the crystalline nature and morphology of surface with ZnO/CoS2 nanoarchitectures. Electrochemical measures such as cyclic voltammetry, galvanostatic charge discharge, and potentiostatic impedance spectroscopy confirmed the battery-type behavior of the material. The synthesized precursors of binder-free ZnO/CoS2 nanostructures depicted an excellent specific capacity of 400.25 C·g−1 at 1 A·g−1, with a predominant cycling capacity of 88. 2% and retention holding of 68% at 10 A·g−1 and 2 A·g−1, even after 4000 cycles, representing an improvement compared to the pristine ZnO and CoS2 electroactive materials. Therefore, the electrochemical and morphological analyses suggest the excellent behavior of the ZnO/CoS2 nanoarchitectures, making them promising for supercapacitors.

Emerging of Heterostructure Materials in Energy Storage: A Review

With the ever-increasing adaption of large-scale energy storage systems and electric devices, the energy storage capability of batteries and supercapacitors has faced increased demand and challenges. The electrodes of these devices have experienced radical change with the introduction of nano-scale materials. As new generation materials, heterostructure materials have attracted increasing attention due to their unique interfaces, robust architectures, and synergistic effects, and thus, the ability to enhance the energy/power outputs as well as the lifespan of batteries. In this review, the recent progress in heterostructure from energy storage fields is summarized. Specifically, the fundamental natures of heterostructures, including charge redistribution, built-in electric field, and associated energy storage mechanisms, are summarized and discussed in detail. Furthermore, various synthesis routes for heterostructures in energy storage fields are roundly reviewed, and their advantages and drawbacks are analyzed. The superiorities and current achievements of heterostructure materials in lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), lithium-sulfur batteries (Li-S batteries), supercapacitors, and other energy storage devices are discussed. Finally, the authors conclude with the current challenges and perspectives of the heterostructure materials for the fields of energy storage.

Photocatalytic hydrogen production from dye contaminated water and electrochemical supercapacitors using carbon nanohorns and TiO2 nanoflower heterogeneous catalysts

In this research, efficient and novel catalysts based on hierarchical carbon nanohorns-titanium nanoflowers have been prepared by one-pot solvothermal process. Hydrogen generation from dye-contaminated water and dye degradation along with electrochemical supercapacitance performance have been investigated using the synthesized hierarchical catalyst to produce 4500 μmol g^-1 h^-1 of hydrogen from the photocatalytically generated aqueous methylene blue and methyl orange dyes, which were degraded up to 90% under natural solar light irradiation. These results offer a new path to generate hydrogen from the aqueous dyes. The catalysts electrode showed 164.6 F g^-1 supercapacitance at 5 mV s^-1 scan rate, which is nearly 1.3 and 1.65-times higher than that of pristine titanium nanoflower and carbon nanohorns electrodes, respectively. Such superior results were achieved due to good crystallinity, improved optical absorption strength, strong chemical composition between the two components, and hierarchical morphology as demonstrated from XRD, UV-DRS, TEM, XPS, and Raman spectral characterizations.