Tailoring morphology of cobalt-nickel layered double hydroxide via different surfactants for high-performance supercapacitor.

Abstract

Tailoring the morphology of cobalt–nickel layered double hydroxide (LDH) electrode material was successfully achieved via the process of cathodic electrodeposition by adding different surfactants (hexamethylenetetramine, dodecyltrimethylammonium bromide (DTAB) or cetyltrimethylammonium bromide). The as-prepared Co0.75Ni0.25(OH)2 samples with surfactants exhibited wrinkle-like, cauliflower-like or net-like structures that corresponded to better electrochemical performances than the untreated one. In particular, a specific capacitance of 1209.1 F g−1 was found for the cauliflower-like Co0.75Ni0.25(OH)2 electrode material using DTAB as the surfactant at a current density of 1 A g−1, whose structure boosted ion diffusion to present a good rate ability of 64% with a 50-fold increase in current density from 1 A g−1 to 50 A g−1. Accordingly, the asymmetric supercapacitor assembled by current LDH electrode and activated carbon electrode showed an energy density as high as 21.3 Wh kg−1 at a power density of 3625 W kg−1. The relationship between surfactant and electrochemical performance of the LDH electrode materials has been discussed.