Construction of hierarchical nanoporous bimetallic copper‑cobalt selenide hollow spheres for hybrid supercapacitor

Nickel-Copper Bimetallic Oxide Nanoparticles Prepared by Simple Coprecipitation Method as High Performance Electrode Materials for Asymmetric Supercapacitors

Supercapacitors with transition bimetallic oxides as pseudocapacitive materials have been of wide concern for their excellent energy storage performance. In this work, a simple coprecipitation method was used to synthesize the precursor, followed by calcination to prepare Ni-Cu bimetallic oxide materials. The structure, morphology and properties of the materials prepared by different precipitating agents and different calcination temperatures of NCO-H2C2O4 precursor were investigated. The optimum precipitant was determined to be H2C2O4, and Ni-Cu nanoparticles with regular lamellar microstructure were obtained at the calcination temperature of 400 °C. The nanostructure and morphology provide a large active channel for the rapid diffusion of electrolyte ions, and the specific capacitance of NCO-H2C2O4-400 electrode material can reach 740.31 F/g Cs at 1 A/g. The investigation of charge storage mechanism shows that the contribution rate of capacitance and diffusion control is about 37.9% and 67.2%, respectively. The electrochemical test results of the asymmetric supercapacitors (ASC) constructed with NCO-H2C2O4-400 and activated carbon show that the specific capacitance, energy density, and power density of the capacitor are 52.66 F/g, 16.45 Wh/kg, and 759.51 W/kg, respectively. Even after 5000 charge/discharge cycles at 5 A/g, it can still keep 90.57% of its initial capacity. This work not only provides competitive electrode materials for energy storage devices but also provides a feasible strategy for producing complex transition metal oxide materials with high capacitance performance.

Ti3C2Tx MXene reinforcement: a nickel-vanadium selenide/MXene based multi-component composite as a battery-type electrode for supercapacitor applications

Designing innovative microstructures and implementing efficient multicomponent strategies are still challenging to achieve high-performance and chemo-mechanically stable electrode materials. Herein, a hierarchical three-dimensional (3D) graphene oxide (GO) assisted Ti3C2Tx MXene aerogel foam (MXene-GAF) impregnated with battery-type bimetallic nickel vanadium selenide (NiVSe) has been prepared through a hydrothermal method followed by freeze-drying (denoted as NiVSe-MXene-GAF). 3D-oriented cellular pore networks benefit the energy storage process through the effective lodging of NiVSe particles, improving the access of the electrolyte to the active sites, and alleviating volume changes during redox reactions. The 3D MXene-GAF conductive matrix and heterostructured interface of MXene-rGO and NiVSe facilitated the rapid transport of electrical charges and ions during the charge-discharge process. As a result of the synergism of these effects, NiVSe-MXene-GAF exhibited remarkable electrochemical performance with a specific capacity of 305.8 mA h g-1 at 1 A g-1 and 99.2% initial coulombic efficiency. The NiVSe-MXene-GAF electrode delivered a specific capacity of 235.1 mA h g-1 even at a high current density of 12 A g-1 with a 76.8% rate performance. The impedance measurements indicated a low bulk solution resistance (Rs = 0.71 Ω) for NiVSe-MXene-GAF. Furthermore, the structural robustness of NiVSe-MXene-GAF guaranteed long-term stability with a 91.7% capacity retention for successive 7000 cycles. Thus, developing NiVSe-MXene-GAF provides a progressive strategy for fabricating high-performance 3D heterostructured electrode materials for energy storage applications.

All-Solid-State Supercapacitors Based on Cobalt Magnesium Telluride Microtubes Decorated with Tellurium Nanotubes

Magnesium (Mg) has received very little exploration on its importance in the realm of battery-type energy storage technologies. They are abundantly present in seawater, and if successfully extracted and utilized in energy storage systems, it could lead to the long-term advancement of human civilization. Here, we fabricated an all-solid-state supercapacitor (ASSSC) using tellurium nanotubes decorated cobalt magnesium telluride microtubes (Te NTs@CoMgTe MTs) clad on nickel foam (NF). Owing to the unique mixed phase hierarchical structure, Te NTs@CoMgTe MTs showcases some advancement in energy storage performance. When tested in a three-electrode system, multiphasic hybrid of elemental Te and metal tellurides, Te NTs@CoMgTe MTs outperforms the monometallic telluride owing to the strong synergistic interaction effect triggered from conductive three components and delivers a long-life span performance up to 15,000 cycles. The fabricated Te NT@CoMgTe MT//AC solid-state device exhibits a maximum areal capacity of 59.2 μAh cm-2 (56.3 mAh g-1) at a current density of 6 mA cm-2 with a maximum energy density of 42.2 Wh kg-1 (46.5 μWh cm-2) at a power density of 6857.1 W kg-1 (7574.6 μW cm-2). The performance of the device is rigid even at different bending angles (0 to 180°) which validates the extensibility of the process for future applications.

Engineering Rich-Cation Vacancies in CuCo2O4 Hollow Spheres with a Large Surface Area Derived from a Template-Free Approach for Ultrahigh Capacity and High-Energy Density Supercapacitors

Intriguing cationic defects with hollow nano-/microstructures are a critical challenge but a potential strategy to discover electrochemical energy conversion and storage devices with improved electrochemical performances. Herein, we successfully produced a highly porous, and large surface area of self-templated CuCo₂O₄ hollow spheres (CCOHSs) with cationic defects via a solvothermal route. We hypothesized that the inside-out Ostwald ripening mechanism of the template-free strategy was the framework for forming the CCOHSs. Cationic defects (Cu) within the CCOHSs were identified by employing various analytical techniques, including energy-dispersive X-ray spectroscopy analysis of both scanning and transmission electron microscopy, X-ray photon spectroscopy, and inductively coupled plasma-atomic emission spectroscopy. The resulting CCOHSs had significant properties, such as a high specific surface area of 98.32 m² g^-1, rich porosity, and battery-type electrode behavior in supercapacitor applications. Notably, the CCOHSs demonstrated an outstanding specific capacity of 1003.7 C g^-1 at 1 A g^-1, with excellent structural integrity and cycle stability. Moreover, the fabricated asymmetric CCOHS//activated carbon device exhibited a high energy density of 65.2 Wh kg^-1 at a power density of 777.8 W kg^-1.

H-CoNiSe2/NC dodecahedral hollow structures for high-performance supercapacitors

The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacities. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe₂/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe₂ and NiSe₂ nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe₂/NC electrode provides high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (90.2% retention after 6000 cycles). In addition, the H-CoNiSe₂/NC//AC hybrid supercapacitor delivers ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cyclic stability (92.1% of the initial capacitance after 6000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.Please confirm the corresponding affiliation for the 'Ali A. Ensafi' author is correctly identified.Error during converting author query response. Please check the eproofing link or feedback pdf for details.

Hierarchical copper cobalt sulfide nanobelt arrays for high performance asymmetric supercapacitors

Rational construction of the morphology of the positive and negative electrodes to assemble a high performance asymmetric supercapacitor.