Fabrication of hybrid supercapacitor device based on NiCo2O4@ZnCo2O4 and the biomass-derived N-doped activated carbon with a honeycomb structure

Research on Interfacial Construction and Energy Storage Performance of Polymetallic Heterostructure Based on Zn-Ni 3d Orbital Modulation and DFT Study

In this study, ZnCo2O4 nanosheets and NiCo2O4 nanowires were successfully grown on nickel foam as anode materials for lithium-ion batteries by a low-temperature hydrothermal and immersion method. The nanosheets offered an enlarged electrically active surface area, and the nanowires provided support for the nanosheets, thereby forming a heterojunction interface. The ZnCo2O4/NiCo2O4 heterojunction demonstrated favorable electrochemical performance in electrochemical tests. In terms of its rated performance, the capacity of the composite electrode recovered to 1050 mAh g-1 when the current density ranged from 0.1 to 1 A g-1; its capacity was maintained even when the current density returned to 0.1 A g-1 after 60 cycles. The diffusion coefficient of lithium ions (DLi+) increased due to the reduction of the interfacial contact resistance under the interfacial electric field of the heterostructure, and they were continuously activated during repeated cycles. This further significantly enhanced the electrochemical activity of the electrode. The analysis results based on the density functional theory revealed the hybridization of the 3d orbitals of Ni and Zn and the augmented electronic state occupancy of the orbitals near the Fermi energy level. This process was accompanied by the migration of electrons, leading to a decrease in the band gap. Meanwhile, the Li+ diffusion barrier decreased, and the conductivity of the electrode materials was enhanced.

Homogeneous activation induced by bacterial cellulose nanofibers to construct interconnected microporous carbons for enhanced capacitive storage

Porous carbons have been widely applied for capacitive energy storage, yet usually suffer from insufficient rate performance because of the sluggish ion transport kinetics in deep and multi-branched pores. Herein, we fabricated an interconnected microporous capacitive carbon (IMCC) by growing D (+)-glucosamine on bacterial cellulose (BC) nanofibers scaffold, followed by carbonization and activation. The BC nanofibers acted as a sacrificial template during pre-carbonization, facilitating the subsequent KOH permeation and homogeneous activation. By taking advantage of the interconnected microporous structure, the IMCC delivers a high capacitance of 302 F g^-1 at 1 A g^-1 and an excellent rate capability of 165 F g^-1 at 100 A g^-1 for aqueous supercapacitor, demonstrating its fast ion transport capability. Impressively, it also shows a superior gravimetric capacity of 177 mAh g^-1 at 0.5 A g^-1 and remains a high value of 72 mAh g^-1 at 20 A g^-1 as a cathode material for Zn-ion hybrid capacitor. This facile and cost-effective design strategy exhibits a great potential to construct carbohydrates-derived interconnected microporous carbon materials for high-rate energy storage.

Role of Electrochemical Techniques for Photovoltaic and Supercapacitor Applications

Electrochemistry forms the base of large-scale production of various materials, encompassing numerous applications in metallurgical engineering, chemical engineering, electrical engineering, and material science. This field is important for energy harvesting applications, especially supercapacitors (SCs) and photovoltaic (PV) devices. This review examines various electrochemical techniques employed to fabricate and characterize PV devices and SCs. Fabricating these energy harvesting devices is carried out by electrochemical methods, including electroreduction, electrocoagulation, sol-gel process, hydrothermal growth, spray pyrolysis, template-assisted growth, and electrodeposition. The characterization techniques used are cyclic voltammetry, electrochemical impedance spectroscopy, photoelectrochemical characterization, galvanostatic charge-discharge, and I-V curve. A study on different recently reported materials is also presented to analyze their performance in various energy harvesting applications regarding their efficiency, fill factor, power density, and energy density. In addition, a comparative study of electrochemical fabrication techniques with others (including physical vapor deposition, mechanical milling, laser ablation, and centrifugal spinning) has been conducted. The various challenges of electrochemistry in PVs and SCs are also highlighted. This review also emphasizes the future perspectives of electrochemistry in energy harvesting applications.

Trimetallic Oxides/GO Composites Optimized with Carbon Ions Radiations for Supercapacitive Electrodes

Hydrothermally synthesized electrodes of Co3O4@MnO2@NiO/GO were produced for use in supercapacitors. Graphene oxide (GO) was incorporated into the nanocomposites used for electrode synthesis due to its great surface area and electrical conductivity. The synergistic alliance among these composites and GO enhances electrode performance, life span, and stability. The structural properties obtained from the X-ray diffraction (XRD) results suggest that nanocomposites are crystalline in nature. The synergistic alliance among these composites and GO enhances electrode performance, life span, and stability. Performance assessment of these electrodes indicates that their characteristic performance was enhanced by C2+ radiation, with the uttermost performance witnessed for electrodes radiated with 5.0 × 1015 ions/cm2.

Flexible synthesis of high-performance electrode materials of N-doped carbon coating MnO nanowires for supercapacitors

The MnO/C composites were obtained by co-precipitation method, which used Mn₃O₄nanomaterials as precursors and dopamine solution after ultrasonic mixing and calcination under N₂atmosphere at different temperatures. By studying the difference of MnO/C nanomaterials formed at different temperatures, it was found that with the increase of calcination temperature, the materials appear obvious agglomeration. The optimal calcination temperature is 400 °C, and the resulting MnO/C is a uniformly dispersed slender nanowire structure. The specific capacitance of MnO/C nanowires can reach 356 F g^-1at 1 A g^-1. In the meantime, the initial capacitance of MnO/C nanowires remains 106% after 5000 cycles. Moreover, the asymmetric supercapacitor was installed, which displays a tremendous energy density of 30.944 Wh kg^-1along with a high power density of 10 kW kg^-1. The composite material reveals a promising prospect in the application of supercapacitors.

Novel Dealloying-Fabricated NiS/NiO Nanoparticles with Superior Cycling Stability for Supercapacitors

NiS/NiO nanoparticles are successfully fabricated through a simple dealloying method and an ion-exchange process. X-ray diffraction demonstrates the existence of NiO and NiS phases, and scanning electron microscopy and transmission electron microscopy imply the nanopore distribution nature and the nanoparticle morphology of the produced material. The electrochemical behaviors are studied by cyclic voltammetry and galvanostatic charge-discharge measurements. The NiS/NiO electrode shows an enhanced specific capacitance of 1260 F g-1 at a current density of 0.5 A g-1. The NiS/NiO//AC device provides a maximum energy density of 17.42 W h kg-1, a high power density of 4000 W kg-1, and a satisfactory cycling performance of 93% capacitance retention after 30,000 cycles.

Three-dimensional hierarchical core-shell CuCo2O4@Co(OH)2 nanoflakes as high-performance electrode materials for flexible supercapacitors

Rational design of composite electrode materials with novel nanostructures plays an important role in improving both high energy density and structure stability of flexible and wearable supercapacitors. Herein, numerous peculiar three-dimensional hierarchical core-shell CuCo₂O₄@Co(OH)₂ nanoflakes directly grown on Ni foam are synthesized via a facile hydrothermal method and subsequent electrodeposition technique. Ultrathin Co(OH)₂ nanosheets arrays vertically anchored on CuCo₂O₄ nanoflakes can not only improve the electrical conductivity, but also provide interconnected channels for ion diffusion and enrich electrochemical active sites to boost faradaic redox reaction, leading to the enhanced electrochemical behavior. Excellent electrochemical performance of CuCo₂O₄@Co(OH)₂ electrode can be reflected on a higher specific capacitance of 1558 F/g and lower resistance compared with that of the pristine CuCo₂O₄ electrode. The asymmetric flexible supercapacitor assembled by the optimized CuCo₂O₄@Co(OH)₂ electrode and activated carbon exhibits high energy density of 62.5 Wh/kg at 893 W/kg, outstanding cycle stability of 88.6% capacitance retention after 10,000 cycles and remarkable mechanical flexibility, performing the best electrochemical behavior among various metal oxides based asymmetric supercapacitors. All above results indicate that the resulted hierarchical core-shell CuCo₂O₄@Co(OH)₂ electrode can be a promising candidate for flexible energy storage devices.

N-Doped carbon as the anode and ZnCo2O4/N-doped carbon nanocomposite as the cathode for high-performance asymmetric supercapacitor application

Herein, we report a one-pot hydrothermal assisted synthesis of ZnCo₂O₄/N-doped carbon nanocomposite (ZC/NC) for high-performance asymmetric supercapacitor applications.

Supercapacitor and non-enzymatic biosensor application of an Mn2O3/NiCo2O4 composite material

Energy storage mechanism and catalytic performance of the Mn₂O₃/NiCo₂O₄ composite material.