Self-assembly of mesoporous ZnCo2O4 nanomaterials: density functional theory calculation and flexible all-solid-state energy storage

Ternary spinel metal oxide ZnCo2O4 with Co2+ at the tetrahedral sites (8a) in the spinel Co3O4 replaced by Zn2+ is promising in energy storage and an economical way to fabricate low-toxicity nanostructured ZnCo2O4 is described. Theoretical calculation confirms the rationality of the experimental scheme and elucidates the underlying reason for the increased band gap. The high electrochemical activity and excellent stability of the ZnCo2O4 NFs//ZnCo2O4 NW symmetrical device suggest large potential for energy storage applications. The fabricated device boasts a capacity of 220.6 F g(-1) at a current density of 2 A g(-1) and long-term cycling stability with 67.5% of the capacitance retained after 8000 cycles. The maximum energy density of 60.04 W h kg(-1) at a power density of 1.4 kW kg(-1) and a power density of 7 kW kg(-1) at an energy density of 23.72 W h kg(-1) are achieved at an operating voltage of 1.4 V. This combined experimental and theoretical study provides insights into the design and controllable preparation of nanomaterials for energy storage applications.