Construction of electron-interactive CoMoO4 @ CoP core–shell structure on boron-doped graphene aerogel as strongly interface coupled hybrid electrodes for high flexible supercapacitor

Abstract

Exploring high energy density, lightweight and self-supporting flexible electrodes is essentially significant to flexible energy storage equipment. Herein, boron-doped three-dimensional porous graphene aerogel (BGA) is engineered and novel flake-like CoP encapsulating flower-like CoMoO4 core–shell structure is arranged on it (CoMoO4@CoP/BGA) utilizing a combination of solvothermal, freeze-drying and vapor deposition techniques. Boron-doped graphene aerogel as flexible self-supporting positrode creates a unique three-dimensional porous interface with a larger specific surface area, which is conducive to exposing more active sites and avoids the additional process of adding binders and conductive agents. The heterointerface engineering of CoP epitaxial growth on CoMoO4 can efficiently enhance electrolyte ions adsorption ability and fast reaction kinetics. As expected, the fabricated CoMoO4@CoP/BGA demonstrates a better specific capacitance of 3056.4F/g than that of CoMoO4/BGA (1582.4F/g) and pure CoMoO4 (669.2F/g), apart from retains the remarkable cyclic stability of 88.4 % after 10,000 cycles. Furthermore, a hybrid supercapacitor composed of CoMoO4@CoP/BGA and BGA can provide a high energy density of 50.2 Wh kg−1 at 800.0 W kg−1, and retains good capacitance retention of 95.6 % after 10,000 cycles, which can be attributed to the large specific surface of B doping 3D porous graphene aerogel and the rich strong coupling interface synergy between CoP and CoMoO4. More importantly, this work provides important guidance for the design of heterojunction electrodes based on heteroatom doped graphene aerogel and phosphides @ oxide based flexible energy storage devices.