Designing of hierarchical lychee fruit-like cobalt-selenide heterostructures with enhanced performance for hybrid supercapacitors

Abstract

Hierarchical porous structured active materials for energy storage devices could increase the surface area, stimulate the charge transport kinetics, and regulate the volume changes during the charge/discharge process. Moreover, the fabrication of heterostructures would increase the interfacial electric field and modify the electronic structure. The features of hierarchical porous heterostructures are more beneficial to enhance the electrochemical properties and robustness of electrode materials for supercapacitors (SCs). Herein, novel hierarchical lychee fruit-like cobalt-oxide@coblat-selenide heterostructure composites (LF-CoO@CoSe HSCs) composed of three-dimensional nanoparticles were prepared via an efficient single-step hydrothermal approach followed by calcination treatment. The LF-CoO@CoSe HSC-500 electrode exhibited a high specific capacity value of 341.6 mAh g−1 (2146.2 F g−1) at a current density of 2 A g−1 compared to the other electrodes annealed at 400 and 600°C (LF-CoO@CoSe HSC-400 (307.2 mAh g−1) and LF-CoO@CoSe HSC-600 (131.8 mAh g−1)), respectively. The LF-CoO@CoSe HSC-500 electrode delivered good cycling stability (77.5%). Furthermore, the pouch-type aqueous hybrid SC (AHSC) was constructed with LF-CoO@CoSe HSC-500 as a positive electrode and porous activated carbon as a negative electrode. The assembled AHSC device delivered maximum energy and power density values of 37.01 Wh kg−1 and 9490 W kg−1, respectively with superior cycling stability of 134% even after 5000 cycles. Furthermore, the fabricated AHSC device was successfully powered a mini light-emitting diode bulb and a timer display. The prepared composites could be an efficient electro-active material for high-capacity SC applications.