A high-performance electrode based on the ZnCo2O4@CoMoO4 core-shell nanosheet arrays on nickel foam and their application in battery-supercapacitor hybrid device

Hierarchical ZnCo2O4@CoMoO4 core-shell nanosheet arrays (ZCCM) were synthesized by coating CoMoO4 nanosheets on the ZnCo2O4 nanosheets on nickel foam (NF) via a facile two-step hydrothermal method, followed by a calcination process. The electrochemical properties of the prepared electrodes were characterized in a three-electrode system as the working electrode. The ZCCM electrode is able to deliver extraordinary specific capacity as high as 1096.08 C g(-1) at the current density of 10 mA cm(-2), and exhibits excellent cycling stability with the specific capacity of 104.1% initial value after 5000 charge/discharge cycles. A battery-supercapacitor hybrid (BSH) device was then assembled using the ZCCM electrode as the positive electrode, activated carbon (AC) as the negative electrode, and 2 M KOH as the electrolyte, and its performance was evaluated. The device outputs the high energy density of 29.24 W h kg(-1) at the power density of 884.57 W kg(-1) and 20.76 W h kg(-1) at the power density of 10526.32 W kg(-1) and shows outstanding cycling stability with 90.95% retention of its initial capacitance after 5000 cycles at the current density of 10 mA cm(-2). (C) 2020 Elsevier Ltd. All rights reserved.