Ni–Mo–S@Ni–P composite materials as binder-free electrodes for aqueous asymmetric supercapacitors with enhanced performance

Abstract

Introducing transition-metal phosphides with high conductivity and high theoretical capacity into transition-metal sulfides is considered to be an effective strategy to improve electrochemical performance by providing rich electrochemical active sites and rich redox reactions. Herein, we report a simple two-step method for the growth of Ni–Mo–S@Ni–P composite materials on Ni foams (NMPS), which delivers a specific capacity of 1062C g−1 (1770 F g−1) at 1 A g−1 in a three-electrode system. Using NMPS as the positive electrode and commercial activated carbon (AC) as the negative electrode, we built an NMPS//AC aqueous asymmetric supercapacitor that shown an energy density of 31.57 Wh kg−1 at a power density of 377.59 W kg−1. This supercapacitor achieved a specific capacity retention of 89.5% after 10000 cycles at 2.5 A g−1. These results reveal that the introduction of Ni–P into Ni–Mo–S is an effective method to obtain enhanced electrochemical properties.