Ion regulation of hollow nickel cobalt layered double hydroxide nanocages derived from ZIF-67 for High-Performance supercapacitors

Abstract

Ni-Co layered double hydroxides (LDHs) have been extensively applied as promising supercapacitor materials due to their ultra-high theoretical capacitance and excellent redox activity. Herein, three-dimensional hollow Ni-Co LDH with staggered nanosheets as the shell was synthesized from ZIF-67 template via the microwave treatment. The Ni-Co LDH revealed a high specific capacitance (2369.0F/g at 0.5 A/g) and a satisfactory rate capability when used as the electrode materials, which could be attributed to its high specific surface area, more exposed active sites, and the synergistic effects between nickel and cobalt ions for promoting mass transfer. Moreover, the asymmetric supercapacitor device possessed the energy density and power density as high as 21.28 Wh/kg and 3741.0 W/kg, respectively. Meanwhile, the Ni-Co LDH//AC device delivered excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. This strategy is promising to be applied in other devices for energy storage, such as Li/Na/K-ion batteries, fuel cells, solar cells, etc.