Ultrafine, high-loading and oxygen-deficient cerium oxide embedded on mesoporous carbon nanosheets for superior lithium-oxygen batteries

The exploitation of advanced cathode materials for rechargeable lithium-oxygen batteries (LOBs) are receiving tremendous attentions worldwide. However, the rational design and regulation on their chemical component and architecture, particularly with regard to the tradeoff between catalyst size and mass loading, toward efficient oxygen catalysis and superior LOB performance are still critical and challenging. Herein, we developed a unique composite of oxygen-deficient cerium oxide (CeOx) embedded on mesoporous carbon (MC) with a concurrent fulfillment of ultrafine crystal (1.98 nm in average) and high mass loading (up to 43.8 wt%), as cathode catalyst for superior LOBs. The ultrafine CeOx distribution sufficiently exposes the catalytic sites, while the highly porous architecture ensures facile electron/mass transfer, thus synergistically contributing to a fast and efficient oxygen catalysis. As a result, the optimized CeOx/MC enables significantly reduced overpotentials for oxygen redox reactions, ultrahigh capacity of 12753 mAh g(-1) and Coulombic efficiency of 92.1% at ultimate-capacity charge-discharge, as well as decent cyclability over 55 cycles at limited-capacity (1000 mAh g(-1)) cycling in LOBs. This work offers an insightful exploration on advanced catalyst materials with simultaneous ultrasmall crystal size and high mass loading, holding a great potential for material engineering in LOBs and other related fields.