Ni-Co Selenide Nanosheet/3D Graphene/Nickel Foam Binder-Free Electrode for High-Performance Supercapacitor.

Transition-metal selenide electrodes have recently attracted increasing interest in supercapacitors resulting from their superior electrochemical performance, lower-cost, and environmental friendliness. Herein, we report a novel bimetallic Ni-Co selenide nanosheet/three-dimensional (3D) graphene/nickel foam binder-free electrode (NiCo2.1Se3.3 NSs/3D G/NF) prepared via chemical vapor deposition followed by a simple two-step hydrothermal process in this paper. The NiCo2.1Se3.3 NSs array vertically on 3D G/NF with a uniform and stable structure without using any chemical binders. This novel electrode is flexible, highly conductive, and exhibits an excellent specific capacitance of ∼742.4 F g-1 at 1 mA cm-2. Furthermore, with a 10-fold increase to 10 mA cm-2, it still retains 471.78 F g-1 and a high cycling stability of ∼83.8% of the initial retention after 1000 cycles at 10 mA cm-2, demonstrating that NiCo2.1Se3.3 NSs/3D G/NF binder-free electrode has potential for energy storage application in high-performance supercapacitor fields.