Ultrathin edge-rich structure of Co3O4 enabling the low charging overpotential of Li-O2 battery

Abstract

• Ultrathin and edge-rich Co 3 O 4 was fabricated and adopted for Li-O 2 catalyst. • The u-Co 3 O 4 tended to induce the formation of thin and loosely aggregated Li 2 O 2 . • High Co 3+ /Co 2+ ratio was benefit for the decomposition of discharge products. The kinetics of the oxygen reduction reaction and oxygen evolution reaction at the rechargeable lithium-oxygen battery cathode are still need to be greatly improved, and transition metal oxides-based catalysts usually suffer from low conductivity and insufficient active sites. Herein, an ultrathin and edge-rich Co 3 O 4 (u-Co 3 O 4 ) catalyst (thickness 3–4 nm) is proposed to lower the overpotential and enhance the cyclability of non-aqueous Li-O 2 battery. The unique structure endows Co 3 O 4 with high electronic conductivity, high specific surface area and abundant active sites. And the high density of Co 3+ ions exposed on surface can serve as active centers for decomposing the discharge products. This u-Co 3 O 4 catalyst tented to induce forming thin and loosely aggregated Li 2 O 2 as discharge products. Electrochemical impedance spectroscopy reveals that a faster charge transmission realized inside the u-Co 3 O 4 -based cell after discharge. Scanning electron microscopy and X-ray diffraction techniques suggest the u-Co 3 O 4 can perfectly catalyze decomposing the discharge products during recharge. Consequently, this u-Co 3 O 4 provided a ∼0.20 V lowered overpotential and an almost 2-fold cycling life for Li-O 2 battery in comparison with traditional Co 3 O 4 catalyst.