Anion engineering in LiCoO2 for highly efficient oxygen electrocatalysis and rechargeable Zn-air batteries

Rational design of bifunctional catalysts for oxygen evolution and reduction reaction (OER and ORR) is vital to the development of Zn-air batteries (ZABs). Herein, we propose a facile strategy of anion engineering to improve the bifunctionality of layered LiCoO2 (LCO) for ZABs. Partial substitution of fluorine for oxygen can not only induce the formation of oxygen vacancies but also modulate the electronic structure of Co, thereby accelerating oxygen electrocatalysis kinetics. The potential gap (Delta E) between the OER potential at 10 mA cm-2 and ORR potential at-3 mA cm-2 of LiCoO1.8F0.2 (LCOF0.2) catalyst (0.986 V) is significantly lower than that of pristine LCO catalyst (1.162 V), indicating a higher bifunctional activity. As an application, a peak power density of the ZABs using LCOF0.2 as the air electrode is 193 mW cm-2, which is 1.53-fold higher than that of the LCO-based ZABs. This study demonstrates the feasibility of F doping to improve the bifunctional electrocatalytic perfor-mance of LiCoO2.