Investigation of the Electrochemical Behavior of CuO-NiO-Co3O4 Nanocomposites for Enhanced Supercapacitor Applications

In the present study, composites incorporating NiO-Co3O4 (NC) and CuO-NiO-Co3O4 (CNC) as active electrode materials were produced through the hydrothermal method and their performance was investigated systematically. The composition, formation, and nanocomposite structure of the fabricated material were characterized by XRD, FTIR, and UV-Vis. The FE-SEM analysis revealed the presence of rod and spherical mixed morphologies. The prepared NC and CNC samples were utilized as supercapacitor electrodes, demonstrating specific capacitances of 262 Fg-1 at a current density of 1 Ag-1. Interestingly, the CNC composite displayed a notable long-term cyclic stability 84.9%, which was observed even after 5000 charge-discharge cycles. The exceptional electrochemical properties observed can be accredited to the harmonious effects of copper oxide addition, the hollow structure, and various metal oxides. This approach holds promise for the development of supercapacitor electrodes. These findings collectively indicate that the hydrothermally synthesized NC and CNC nanocomposites exhibit potential as high-performance electrodes for supercapacitor applications.

Micro/Nano Energy Storage Devices Based on Composite Electrode Materials

It is vital to improve the electrochemical performance of negative materials for energy storage devices. The synergistic effect between the composites can improve the total performance. In this work, we prepare α-Fe2O3@MnO2 on carbon cloth through hydrothermal strategies and subsequent electrochemical deposition. The α-Fe2O3@MnO2 hybrid structure benefits electron transfer efficiency and avoids the rapid decay of capacitance caused by volume expansion. The specific capacitance of the as-obtained product is 615 mF cm−2 at 2 mA cm−2. Moreover, a flexible supercapacitor presents an energy density of 0.102 mWh cm−3 at 4.2 W cm−2. Bending tests of the device at different angles show excellent mechanical flexibility.

Hierarchical Co3O4@Ni3S2 electrode materials for energy storage and conversion

Transition metal oxides are considered to be one of the most potential electrode materials. However, poor conductivity and insufficient active sites limit their actual applications. Rationally designed electrode materials with unique structural features can be ascribed to the efficient route for enhancing electrochemical performance. Here, we report hybrid Co₃O₄@Ni₃S₂ nanostructures obtained via a hydrothermal strategy and subsequent electrodeposition process. The obtained products can be used as electrodes for a hybrid supercapacitor with a specific capacity of 1071 C g^-1 at 1 A g^-1 and excellent rate capability. The as-assembled device delivers an energy density of 77.92 W h kg^-1 at 2880 W kg^-1. As an electrocatalyst, the above electrode possesses an overpotential of 237.6 mV at 50 mA cm^-2 for oxygen evolution reaction.

Prolific intercalation of VO2 (D)/polypyrrole/g-C3N4 as an energy storing electrode with remarkable capacitance

VO2 (D)/polypyrrole/g-C3N4 composites are synthesized through in situ chemical oxidation polymerization, and used as an electrode material for excellent energy storage.

Transition Metal Oxide Electrode Materials for Supercapacitors: A Review of Recent Developments

In the past decades, the energy consumption of nonrenewable fossil fuels has been increasing, which severely threatens human life. Thus, it is very urgent to develop renewable and reliable energy storage devices with features of environmental harmlessness and low cost. High power density, excellent cycle stability, and a fast charge/discharge process make supercapacitors a promising energy device. However, the energy density of supercapacitors is still less than that of ordinary batteries. As is known to all, the electrochemical performance of supercapacitors is largely dependent on electrode materials. In this review, we firstly introduced six typical transition metal oxides (TMOs) for supercapacitor electrodes, including RuO₂, Co₃O₄, MnO₂, ZnO, XCo₂O₄ (X = Mn, Cu, Ni), and AMoO₄ (A = Co, Mn, Ni, Zn). Secondly, the problems of these TMOs in practical application are presented and the corresponding feasible solutions are clarified. Then, we summarize the latest developments of the six TMOs for supercapacitor electrodes. Finally, we discuss the developing trend of supercapacitors and give some recommendations for the future of supercapacitors.

A flexible hybrid capacitor based an NiCo2S4 nanowire electrode with an ultrahigh capacitance

It is well-known that the excellent cycling stability and high energy density of electrode materials is very important for supercapacitors. However, their actual performance falls far behind and does not satisfy the practical demand. In this study, we synthesized NiCo₂S₄ nanowire bundles on a nickel foam via facile hydrothermal routes. The as-obtained product as an electrode material possesses excellent specific surface area, which suggests that numerous active sites on the electrode surface can shorten the diffusion channel of ions. The assembled asymmetric supercapacitor delivers an energy density of 57.36 W h kg^-1 at 1412.92 W kg^-1. Also, it exhibits excellent mechanical stability even at different bending angles.

A facile synthetic protocol of α-Fe2O3@FeS2 nanocrystals for advanced electrochemical capacitors

In this work, we report granular α-Fe₂O₃@FeS₂ nanocrystals by a one-pot hydrothermal route. The as-obtained product as an electrode material shows excellent charge transfer ability and cyclic stability.

Mesoporous Co–Mo–S nanosheet networks as cathode materials for flexible electrochemical capacitors

In this study, we synthesized numerous Co–Mo–S nanosheet networks as electrode materials by a two-step hydrothermal strategy. It delivers a specific capacity of 510 C g−1 at 1 A g−1.

Novel synthesis of hierarchical NiGa2O4@MnO2 core-shell hetero-nanostructured nanowall arrays on carbon cloth for high-performance all-solid-state asymmetrical supercapacitors

A hierarchical NiGa₂O₄@MnO₂ core-shell nanowall arrays have been grown on carbon cloth by stepwise design and fabrication. Ultrathin MnO₂ nanoflakes are revealed to grow uniformly on the porous NiGa₂O₄ nanowalls with many interparticle mesopores, resulting in the formation of 3D core-shell nanowall arrays with hierarchical architecture. The as-synthesized product as a binder-free electrode possesses a high specific capacitance of 1700 F g^-1 at 1 A g^-1 and 90% capacitance retention after 10,000 cycles at 10 A g^-1. Furthermore, an asymmetrical solid-state supercapacitor assembled by the NiGa₂O₄@MnO₂ and N-CMK-3 exhibits an energy density of 0.59 Wh cm^-3 at a power density of 48 W cm^-3, and excellent cycling stability (80% of initial capacitance retention after 5000 cycles at 6 mA cm^-2). The remarkable electrochemical performances can be attributed to its novel nanostructure with high surface area, convenient ion transport paths and favorable structure stability. These results display an effective method for fabrication of different core-shell nanostructure on conductive substrates, which brings new design opportunities of device configuration for next energy storage devices.

Toward materials-by-design: achieving functional materials with physical and chemical effects

Advances in renewable and sustainable energy technologies critically depend on our ability to rationally design and process target materials with optimized performances. Advanced material design and discovery are ideally involved in material prediction, synthesis and characterization. Control of material crystallization enables the rational design and discovery of novel functional inorganic materials in multi-scale. Material processing can be adjusted by various physical fields and chemical effects at different energy states. Material microstructure, architecture and functionality can thus be modified by multiple design methodologies. In this review, we show typical examples using physical and chemical methods to shape inorganic functional materials and evaluate their specific applications in Na-air batteries, Li-ion batteries and supercapacitors. Furthermore, this review also provides insight into the understanding of synthesis-structure relationship of inorganic functional materials.

Bi-functional Mo and P co-doped ZnCo-LDH nanosheets as high performance electrocatalysts for boosting overall water splitting

To rationally construct electrode structures with high activity is very significant for bi-functionalization conversion systems.

Phase and morphology evolution of CoAl LDH nanosheets towards advanced supercapacitor applications

Al-Based LDH materials have been considered as promising active electrode materials for pseudocapacitors due to their structural tunability.

Asymmetric pseudo-capacitors based on dendrite-like MnO2 nanostructures

Dendrite-like MnO₂ nanostructures grown on carbon cloth are successfully prepared by a facile one-step route.

Toward a high performance asymmetric hybrid capacitor by electrode optimization

Molybdenum disulfide (MoS₂) is an extremely promising electrode material for supercapacitors due to its superior electrochemical performance and conductivity.

Mixed transition metal oxide nanowire arrays enabling hybrid capacitor performance enhancement

Herein, we report MnO₂@NiCo₂O₄ nanowire bundles grown on Ni foam by a facile hydrothermal route. The as-prepared products exhibit high areal capacitance of 452.1 C g⁻¹ at 10 A g⁻¹ and 88.6% of initial capacitance after 10 000 cycles.

Transition metal oxide@hydroxide assemblies as electrode materials for asymmetric hybrid capacitors with excellent cycling stabilities

In this work, three-dimensional cactus-like Co₃O₄@Ni(OH)₂ electrode materials are grown directly on Ni foam via a two-step hydrothermal method. The as-prepared products possess a specific capacitance of 464.5 C g⁻¹ at 0.5 A g⁻¹ and 91.67% capacitance retention after 20 000 cycles. The as-assembled device using the as-synthesized samples as positive electrodes delivers an energy density of 112.5 W h kg⁻¹ at a power density of 1350 W h kg⁻¹. The superior electrochemical performance of the electrode materials can be attributed to their unique structure, the synergistic effect between Co₃O₄ and Ni(OH)₂ materials and reversible reaction kinetics. It suggests that the products are potential alternatives in future energy storage devices.

In this work, three-dimensional cactus-like Co₃O₄@Ni(OH)₂ electrode materials are grown directly on Ni foam via a two-step hydrothermal method.