Systematic study on electrochemical performances of Co-Ni layered double hydroxides grown directly on stainless steel wire mesh

Transition metal cobalt-nickel hydroxides have been widely studied as electrode materials for hybrid supercapacitors (HSCs) due to their unique active component properties. Nevertheless, the influencing factors and optimization of their electrochemical performances are still being studied and discussed. In this paper, Co-Ni layered double hydroxide (LDH) porous structure assembled from nanosheets was formed directly on stainless steel wire mesh (SS) by potentiostatic deposition. The bimetallic synergistic effect and porous structure of Co-Ni LDHs are favorable to their electrochemical performances. The Co0.5Ni0.5(OH)(2)-SS (nominal composition) electrode has the optimal Co:Ni molar ratio, and its specific capacity values are 474.2 - 320.1 C g(-1) at different current densities (1-10 A g(-1)) in 1 M KOH electrolyte. In addition, the concentration of KOH electrolyte also plays an important role on the electrochemical mechanism and performances. Compared with 6 M KOH electrolyte, lower concentration (1 and 3 M) is much more conductive to the microstructural stability and electrochemical behaviors of Co0.5Ni0.5(OH)(2)-SS electrode. Moreover, the fabricated Co0.5Ni0.5(OH)(2)-SS//AC-SS HSC device exhibits a good cycling stability, and the maximum energy density is about 10.9 Wh kg(-1) at 548.0 W kg(-1).

Automated summary

This study investigates the optimization of cobalt-nickel hydroxides as electrode materials for hybrid supercapacitors and their electrochemical performances, indicating the favorable bimetallic synergistic effect and porous structure, as well as the important influence of KOH electrolyte concentration on performance.