Oxygen defect engineering endows Co3O4 nanosheets with advanced aluminum ion storage

Abstract

Atomic-level structure modulation is an effective way to boost ionic diffusion kinetics and improve the cycling stability. To relieve the strong coulombic ion–lattice interactions originating from trivalent Al³⁺ ions, herein oxygen-deficient Co₃O_4−x porous nanosheets are fabricated via a facile NaBH₄ reduction strategy using a metal–organic framework template. Electrochemical kinetics analysis and theoretical calculation results reveal good pseudocapacitive property, appropriate diffusion capability and Al³⁺ formation energy, corroborating fast Al³⁺ ion storage/release kinetics and high Al³⁺ storage capacity. Specifically, Co₃O_4−x porous nanosheets exhibit a high reversible capacity of 442.3 mA h g⁻¹ at 1.0 A g⁻¹ and retain 104.2 mA h g⁻¹ after 1800 cycles, remarkably higher than those of the previously reported Co₃O₄-based cathode materials. Furthermore, ex situ analyses reveal the conversion reaction mechanism of the Co₃O_4−x cathode, followed by its high structural stability upon extended cycling.