Modified Graphene Sheets as Promising Cathode Catalysts for Li–O₂ Batteries: A First-Principles Study

The Li–O 2 battery is a promising energy storage device; however, it is seriously hindered by the sluggish chemical reaction of cathode catalysts. Here, we study a cathode catalyst based on B- and N-doped and BN codoping on Stone–Wales defect graphene (SWG) by first-principles calculations. Interestingly, BN codoped structure not only increases the stability of the system but also exhibits extremely low discharge and charge overpotentials. The corresponding value of overpotential for the oxygen reduction reaction is 0.23 V, and the for oxygen evolution reaction, it is 0.29 V, indicating that the BN codoped structure is an excellent cathode catalyst for Li–O 2 batteries. Further analysis proves that the overpotential is strongly determined by the adsorption behavior of the intermediates in the rate-determining steps (RDS). These findings elucidate the quantitative correlations between intermediate adsorption and catalytic behavior, which provides a promising approach in designing of Li–O 2 battery cathode catalysts with highly activity. In addition, taking BN-SWG as a test case, we find that BN-SWG does not promote the formation of side product Li 2 CO 3 . On the other hand, it will not lead to the decomposition of the dimethyl sulfoxide electrolytes, indicating that BN-SWG can improve the reversible cycle life without producing Li 2 CO 3 -like species in Li–O 2 batteries.