Coupling (NixCo1-x)0.85Se with N-doped MoSe2 for hybrid supercapacitors with remarkable cyclic durability

Abstract

Despite being a novel supercapacitive material, the widespread application of layered molybdenum diselenide has been hindered by its low specific capacity, significant volume changes during electrochemical reactions, and slow kinetics. In this study, we successfully combined (NixCo1-x)0.85Se nanoparticles with N-MoSe2 to create (NixCo1-x)0.85Se/N-MoSe2 hybrids (labeled as AxB1-xC). The electrochemical performance of AxB1-xC was dramatically improved due to the synergistic effects between nickel and cobalt, as well as between (NixCo1-x)0.85Se and N-MoSe2. Among the various AxB1-xC electrodes, the A0.8B0.2C electrode exhibited the best electrochemical performance when the Ni/Co ratio was 0.8/0.2. It provided a specific capacity of 397.9 C g−1 at 0.5 A/g and retained 220.0 C g−1 after 2,000 cycles at 10 A/g. Furthermore, we constructed an A0.8B0.2C//AC hybrid supercapacitor to assess its energy storage capability. The A0.8B0.2C//AC device achieved a specific capacitance of 72.6 F g−1 at 0.5 A/g with an energy density of 25.8 Wh kg−1 at 400 W kg−1. The capacitive retention of the A0.8B0.2C//AC device was 92.9 % after 40,000 cycles at 3 A/g. Impressively, a self-constructed A0.8B0.2C//AC device could power a timer for about 24 min, demonstrating its potential for practical applications.