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

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.