Ni3+ doped cobalt–nickel layered double hydroxides as high-performance electrode materials for supercapacitors

Abstract

Co–Ni layered double hydroxides (LDHs), as promising supercapacitor electrode materials with high specific capacity, have suffered from poor rate properties and cycling stability. Doping and topochemical oxidation of Ni ions is considered as an efficient route to overcome these drawbacks. In this work, Ni³⁺ doped cobalt–nickel layered double hydroxides (Co–Ni-LDHs) were synthesized by pulse laser ablation of a Ni target in CoCl₂ aqueous solution. The existence of Ni³⁺ ions doped in Co–Ni-LDHs decreases the conductive resistance, and increases the mobility of surface charge and transfer rate of the electrolyte. As a result, the Ni³⁺ doped Co–Ni-LDHs display a maximum specific capacitance of 2275 F g⁻¹ and 1450 F g⁻¹ at the current density of 1 A g⁻¹ and 20 A g⁻¹, respectively, indicating a high rate of specific capacitance. Moreover, the capacitance retention is 80% after 1800 cycles at the current density of 6 A g⁻¹, manifesting good cycling stability of Ni³⁺ doped Co–Ni-LDHs.