High-performance solid-state supercapacitor based on Ni-Co layered double hydroxide@Co3O4 nanocubes and spongy graphene electrodes

Increasing energy density and cycle stability pose the biggest challenges for developing efficient and affordable energy storage devices. Supercapacitor electrode materials with synergistic 3D architectural frameworks are designed to address the most crucial issues. Herein, 3D hierarchical Ni-Co layered double hydroxides (LDH) wrapped around porous Co3O4 nanocube (Nc) derived from ZIF-67 as a template are successfully synthesized. The Ni-Co LDH@Co3O4 Nc electrode has the highest specific capacitance (1866 F g(-1)) at 2 A g(-1) with outstanding rate capability compared to all formulation material-based positive electrodes. Moreover, the asymmetric solid-state supercapacitor device (ASC) has been successfully synthesized and constructed based on a full cell with 3D Ni-Co LDH@Co3O4 Nc and three-dimensional spongy graphene (3DSGr). The ASC delivers the highest energy density of 66.7 Wh kg(-1) with a power density of 800 W kg(-1) and superior recyclability over 10,500 cycles with a holding capacitance retention ratio of 90.5% and 99.8% of Coulombic efficiency. The construction design of highly electrochemically active materials with an outstanding asymmetric configuration of the Ni-Co LDH@Co3O4 Nc//3DSGr provides an efficient, tunable, and affordable asymmetric supercapacitor device.

Automated summary

Researchers have successfully developed a new type of supercapacitor electrode material with a three-dimensional layered structure to improve energy density and cycle stability. By constructing this material, an asymmetric supercapacitor device with excellent rate capability and cycle stability has been manufactured.