Morphological modulation of NiCo2Se4 nanotubes through hydrothermal selenization for asymmetric supercapacitor

Abstract

Transition metal selenide electrodes have attracted much attention in supercapacitor applications, due to their high electrical conductivity, superior electroactivity, and excellent structural stability. However, preparing the transition metal selenide with elaborate nanostructures remains a challenge. Herein, a two-step hydrothermal method was utilized to design NiCo2Se4 electrode with hollow nanotubes. By controlling the feeding of selenium in the selenization process, the formation mechanism of NiCo2Se4 nanotubes was investigated. In detail, the characterization methods, such as FESEM, TEM, XRD, EDS, and Raman spectroscopy, were implemented to study the influence of selenium on the morphology, structure composition, and electrochemical performance of NiCo2Se4 electrode. Moreover, an asymmetric supercapacitor was fabricated using the optimized NiCo2Se4 as positive electrode and activated carbon (AC) as negative electrode, showing high energy density of 25.0 Wh kg−1 at a power density of 490 W kg−1 and excellent cycle stability (93% of initial capacitance after 5000 cycles). This study will shed light on the facile design of transition metal selenide electrode with high electrochemical performance for supercapacitor applications.