Sugar gourd-like NiCo layered double hydroxide @ NiMoO4 hierarchical core-shell material for high-performance asymmetric supercapacitors

Abstract

As one of the strategies for preparing electrode materials with excellent electrochemical properties, reasonable structural design has been widely used to improve the performance of electrode materials. In this work, a core-shell structure with a unique sugar gourd-like appearance is designed, in which NiMoO4 (NMO) nanorods string together multiple NiCo-LDH (NCL) hollow nanocages to form NCL@NMO/NF composite electrode. The unique structure and the synergistic effect between the two substances give it high cycle stability and excellent capacity. DFT calculations show that the electronic structure at the NCL@NMO heterogeneous interface changes after compounding, so that electrons are transferred from the NCL to the NMO surface, and the difference in the work function promotes the transfer of electrons and accelerates the reaction rate. When used as the positive electrode of asymmetric supercapacitor (ASC), the material exhibits a specific capacity of 1186 C g−1 at a current density of 1 A g−1, and a capacity retention rate of 85.5 % after 5000 cycles at 5 A g−1. In addition, the assembled NCL@NMO/NF//AC ASC exhibits a high energy density of 80.38 Wh kg−1 at a power density of 800 W kg−1, and has high cycle stability (89.2 % after 5000 cycles).