ABSTRACT
Li-O2 batteries are attracting considerable attention as a promising power source for electric vehicles as they have the highest theoretical energy density among reported rechargeable batteries. However, the low energy density and efficiency of Li-O2 batteries still act as limiting factors in real cell implementations. This study proposes the cathode structure engineering strategy by tuning the thickness of a catalyst layer to enhance the Li-O2 battery performance. The construction of the Li-O2 battery with a thinner porous cathode leads less parasitic reactions at the solid electrolyte interface, maximization of the catalyst utilization, and facile transport of oxygen gas into the cathode. A remarkably high specific capacity of 33,009 mAh g-1 and the extended electrochemical stability for 75 cycles at a 1000 mAh g-1 limited capacity and 100 mA g-1 were achieved when using the porous Co/CeO1.88-nitrogen-doped carbon nanorod cathode. Further, a high discharge capacity of 20,279 mAh g-1 was also achieved at a relatively higher current density of 300 mA g-1. This work suggests the ideal cathode structure and the feasibility of the Co/CeO1.88-nitrogen-doped carbon nanorod as the cathode material, which can minimize the areal cathode catalyst loading and maximize the gravimetric energy density.
