Hierarchical porous Co₃O₄ films as cathode catalysts of rechargeable Li-O₂ batteries

The high cost of noble metals and the instability of carbon materials have caused people to pay great attention to the use of transition metal oxides as Li-O₂ battery cathode catalysts. On the other hand, the Li-O ₂ batteries' performances are seriously affected by the O₂ diffusion kinetics, which causes various porous structures to be used for generating fluent channels in the cathode catalysts. Herein, hierarchical porous Co₃O₄ films composed of free-standing hollowed flakes are deposited on Ni foams by an electrochemical assisted method. Mesopores with different sizes in the flakes can be obtained by adjusting the calcination temperature. The Li-O₂ batteries catalyzed by the porous films calcined at 300°C have a capacity of 2460 mA h g^-1, and a performance of more than 35 discharge/charge cycles with a capacity limitation of 1000 mA h g^-1.