A novel MoP2@Ni2P nanosheet and an individual kelp-based porous carbon for assembly a unique high performance asymmetric supercapacitor

Abstract

In order to improve the specific capacity and energy density of the asymmetric supercapacitors, it is necessary to design positive and negative electrode materials with special structure and good electrochemical properties. Herein, a novel MoP2@Ni2P nanosheet material is prepared by one-step simple hydrothermal synthesis and low temperature phosphating method, which exhibits excellent specific capacity of 133.6 mAh g−1 at 0.5 A g−1. In addition, a kelp based porous carbon nanosheet material (AKPC) is prepared via swollen the kelp in a sodium chloride solution and then subjected to an activation and carbonization. Because of its biomaterial unique morphology, the carbon material shows ultra-high specific surface area (1197 m2 g−1) and large pore volume, thus possess a high specific capacitance of 180 F g−1 at 0.5 A g−1. Moreover, the above two materials are assembled into a unique asymmetric supercapacitor with operating voltage of 1.65 V, which has demonstrated a high energy density of 31.5 Wh kg−1 and excellent cycling stability with 81 % capacitance retention after 1500 cycles in aqueous electrolyte. The successful preparation of the asymmetric device provides a new idea for the development of high performance electronic devices.