Downsizing metal–organic frameworks with distinct morphologies as cathode materials for high-capacity Li–O2 batteries

Abstract

Rechargeable nonaqueous Li–O₂ batteries have been considered as one of the most promising candidate energy storage devices. In this work, metal–organic framework nanomaterials with distinct sizes and morphologies were successfully synthesized via a facile solvothermal method. By using modulators in a mixed solvent system, the dimension of Co-MOF-74 could be reduced down to several unit cell lengths. Furthermore, high specific capacities (11 350 mA h g⁻¹ at 100 mA g⁻¹) were achieved when they were directly employed as cathode materials for Li–O₂ batteries. In addition to the high density of unsaturated active sites for electrochemistry, as provided by the MOF skeleton itself, the size confinement and inherent defects of the nanocrystals have further offered efficient diffusion paths with lowered transport barriers, contributing to their high performance in Li–O₂ batteries.