Facile synthesis and incomplete sulfidation of nickel-cobalt-aluminum ternary layered hydroxide binder-free electrode with enhanced supercapacitor properties

Layered transition metal hydroxide, a clay-like material, possessing characteristics of large specific surface area, adjustable fraction, and plentiful active components make it a potential energy storage material, especially in the background of energy and environment crisis. Herein, comprehensive applications of cobalt-aluminum-based LDHs for supercapacitors are proposed. Binder-free electrodes were successfully synthesized such as Co3Al1- LDH/Ni, Ni2Co1Al1-LDH/Ni and Ni1Co2Al1-LDH/Ni using a rapid green hydrothermal approach. Subsequently, further sulfuration was carried out to obtain a heterostructure of sulfide/layered hydroxide. The electrochemical energy storage properties of binder-free electrodes were investigated, which show that the performance of ternary LDH electrode is better than that of binary one, and the incompletely sulfuration Ni1Co2S/Ni has the optimal electrochemical performance among all electrodes, with a specific capacitance of 2186 F g-1 at 1 A g-1. The Ni1Co2S//AG hybrid supercapacitor (HSC) device assembled with Ni1Co2S as positive electrode and active graphene as negative electrode delivers an energy density of 13 Wh kg-1 at a power density of 749 W kg-1, good rate capability and cycling stability.

Automated summary

Layered transition metal hydroxide is a potential energy storage material with large specific surface area, adjustable composition, and abundant active components. The performance of the binder-free electrodes in the study showed that the ternary LDH electrode had better electrochemical properties than the binary one, and the partially sulfide Ni1Co2S/Ni electrode exhibited the optimal performance. The hybrid supercapacitor device assembled with Ni1Co2S as the positive electrode and active graphene as the negative electrode displayed high energy density, good rate capability, and cycling stability.