High-performance hybrid supercapacitors based on electrodeposited amorphous bimetallic nickel cobalt phosphide nanosheets

In this article, an amorphous bimetallic nickel cobalt phosphide (NiCoP) thin film composed of 2D nanosheets architecture was directly grown on Ni foam substrate by using one-step electrodeposition route and utilized as an efficient binder-free cathode for hybrid supercapacitors (HSCs). Particularly, the molar ratio of Ni/Co of the bimetallic NiCoP electrodes was systemically optimized for acquiring superior capacitive features. According to the synergistic advantages of ultrathin 2D nanosheets, good electrical conductivity of metal phosphides, and amorphous characteristics, the optimized bimetallic Ni0.5Co0.5P electrode exhibited the high specific capacity of 42.2 mA h g−1 at a current density of 1 A g−1, which was superior to the corresponding mono-metallic phosphides of NiP (38.8 mA h g−1) and CoP (21.5 mA h g−1). Moreover, an as-fabricated HSC device assembled with modified activated carbon anode and the Ni0.5Co0.5P cathode delivered not only an impressive specific capacity of 56.5 mA h g−1 at 1 A g−1, but also high energy density of 45.2 Wh kg−1 along with a power density of 800 W kg−1. Furthermore, the HSC device demonstrated good cycling stability with 86.7% capacity retention even after 10,000 cycles at 2 A g−1. Thereby, the facile and simple electrodeposition process and superior electrochemical performance of the electrodeposited NiCoP materials makes them as promising electrode materials for energy storage applications.