Co₃O₄ nanoparticle-dotted hierarchical-assembled carbon nanosheet framework catalysts with the formation/decomposition mechanisms of Li₂O₂ for smart lithium-oxygen batteries†

Li-O₂ batteries (LOBs) have been regarded as promising candidates for the next generation of electric vehicles owing to their excellent energy density. Nevertheless, the practical application of LOBs with a sensible cathode material has largely been blocked due to their low-activity catalysts and inefficient product evolution. Combining carbon and metal oxide is one of the most effective strategies to realize the high capacity and lower overpotential for boosting the Li-O₂ battery performance. Herein, cobalt oxide (Co₃O₄) nanoparticle-dotted hierarchical-assembled carbon nanosheet frameworks (Co₃O₄-HCNFs) were fabricated using a facile two-step carbonization-calcined route and applied as high-efficiency electrochemical catalysts for Li-O₂ batteries. Co₃O₄ has been proved to be effective for the full composition/decomposition of generated Li₂O₂ thin films during the oxygen reduction reaction process (ORR) and the oxygen evolution reaction process (OER). Furthermore, the cobalt oxide nanoparticle-dotted hierarchical-assembled carbon nanosheet frameworks satisfy the relevant requirements including controlled morphology and efficient volume change accommodation, which delivered a high-performance with a large specific capacity of 14 949 mA h g⁻¹ and superior cycling stability with 180 cycles. This study designs a smart strategy with high-performance Co₃O₄ cathodes for Li-O₂ batteries and the composition/decomposition mechanisms of Li₂O₂ films, showing a favorable method for recomposing the future design of Co₃O₄-based advanced energy materials.