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

Three-dimensional hollow Ni-Co LDH with staggered nanosheets as the shell is synthesized from ZIF-67 template via the microwave treatment. The Ni-Co LDH electrode exhibits an ultrahigh high specific capacitance (2369.0F/g at 0.5 A/g) and the Ni-Co LDH//AC device delivers excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. This work provides a promising way for fabricating unique and complex 3D hollow structure with satisfactory electrochemical performance from MOF templates. • Three-dimensional hollow Ni-Co LDH nanocages are successfully synthesized from ZIF-67 template via microwave heating treatment. • Its unique architecture can promote the free diffusion and lessen the transfer distance for electrons and ions during the process of electrochemical reactions. • The synergistic effects of Ni and Co ions can provide multiple redox reactions during the electrochemical charge/discharge process. • The Ni-Co LDH electrode exhibits a superior capacitance of 2369.0F/g at 0.5 A/g and excellent rate capability. • The Ni-Co LDH//AC asymmetric supercapacitor delivers excellent cycling stability with 83.6% capacitance retention after 10,000 cycles. 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.