Hierarchical walnut-like Ni_0.5Co_0.5O hollow nanospheres comprising ultra-thin nanosheets for advanced energy storage devices

Abstract

As-prepared hierarchical Ni0.5Co0.5O hollow nanospheres comprising ultra-thin nanosheets exhibit a superior specific capacity and excellent rate performance due to the abundant active sites and fascinating narrow-gap channel.

A High‐Energy Aqueous Sodium‐Ion Capacitor with Nickel Hexacyanoferrate and Graphene Electrodes

“…Further, the Na‐ion aqueous capacitor device was fabricated using Ni‐HCF as positive and graphene as negative electrodes. The operating window of the Ni‐HCF and graphene electrodes (shown in Figure (A)) were in the range of −0.2 to 1 V and 0 to −1 V respectively, hence it is expected that the fabricated device will work in the range of 2.0 V. After balancing the charges accumulated on each electrode using the method given by Jiang et al., the Na‐ion hybrid capacitor is fabricated. The CV profiles of the Ni‐HCF∥graphene device shows that the device is working well in the potential range of 0 to 2.0 V without any signs of evolution as evident from Figure (B).…”

“…The electrochemical studies of the working electrodes, and the Ni‐HCF∥graphene Na‐ion hybrid capacitors were examined using cyclic voltammetry (CV) at different scan rates, electrochemical impedance spectroscopy (EIS) and galvanostatic charge−discharge (CD) measurements at different current densities using an Autolab PGSTAT302N electrochemical workstation. The specific capacity of Ni‐HCF electrodes calculated from the CD profiles using Equation : …”

“…The specific capacitance, energy density ( E ), and power density ( P ) of the Ni‐HCF∥graphene device was calculated using Equations (3)–: …”

Co0.5Ni0.5MoO4 Double‐Shelled Hollow Spheres with Enhanced Electrochemical Performance for Supercapacitors and Lithium‐Ion Batteries

“…The Ni 2p core‐level spectrum (Figure b) shows two main peaks at 856.0 and 873.5 eV, which are attributed to the Ni 2p 3/2 and Ni 2p 1/2 of Ni 2+ . The peaks at 857.6 (2p 3/2 ) and 875.0 eV (2p 1/2 ) indicate the existence of Ni 3+ . As for Mo 3d spectrum, two characteristic peaks at 232.3 and 235.5 eV (Figure c) are assigned to Mo 3d 5/2 and Mo 3d 3/2 , respectively, of Mo 6+ .…”

“…Electrochemical impedance spectroscopy (EIS) spectra are collected to investigate the nature of charge transfer (Figure S9, Supporting Information). Co 0.5 Ni 0.5 MoO 4 DSHSs show a charge transfer resistance (determined from the size of semicircle in high‐frequency region) and diffusive resistance (determined from the slope of the plots in low‐frequency region) between those of NiMoO 4 and CoMoO 4 , suggesting that the introduction of Co into NiMoO 4 improves the electric conductivity as well as electrochemical activity …”