Spatially-controlled porous nanoflake arrays derived from MOFs: An efficiently long-life oxygen electrode

Abstract

The urgent expectation of the next-generation energy storage devices for electric vehicles has driven researchers’ attention to the lithium-oxygen (Li-O2) batteries due to the satisfied specific energy density. Herein, spatially-controlled Co3O4 nanoflake arrays with three-dimensional-networked morphology are adopted as flexible and self-standing oxygen cathodes in Li-O2 batteries. The spinel-phase Co3O4 nanoflakes were converted from two-dimension metal-organic frameworks with abundant available channels and large specific surface area. The open-structure nanoflake arrays possess sufficient Li2O2/cathode contact interface, great bifunctional catalytic performance and adequate Li2O2 accommodation, leading to the enhanced electrochemical performance of the Li-O2 batteries. As expected, the binder-free porous Co3O4/CT cathode delivers a high capacity of 6,509 mAh·g−1 (200 mA·g−1) and enhanced stability over 100 cycles (limited by 1,000 mAh·g−1). In addition, pouch-type Li-O2 batteries were successfully designed and cycled with Co3O4/CT cathode as oxygen electrodes, demonstrating its potential application for flexible electronics and wearable energy storage devices.