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

Abstract

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.