Double-layer honeycomb AlP as a promising catalyst for Li-O2 and Na-O2 batteries

Abstract

Nonaqueous Li-O2 and Na-O2 batteries are promising next-generation energy storage devices due to the outstanding energy density. Nevertheless, the current issue needed to be conquered is the sluggish electrochemical reactions, which can count on the choice of an active catalyst. This work theoretically investigates the two-dimensional (2D) double-layer honeycomb (DLHC) AlP as a cathode catalyst for Li-O2 and Na-O2 batteries. It is found that the DLHC AlP can lead to the O2 dissociation at the specific catalytic site with a low energy barrier. Different electrochemical reduction paths are proposed for understanding the discharge process. It is predicted that LiO2 and Li2O2 are the major products in Li-O2 batteries, and the discharge and charge overpotentials are predicted to be less than 0.68 V; while both NaO2 and Na2O2 are the possible products in Na-O2 batteries, and overpotentials are less than 0.27 V for charge and 0.43 V for discharge. The DLHC AlP can provide strong affinities to intermediate products, and the adsorption causes a local reversible phase transition with the formation of Al-O bonds. Our work suggests the DLHC AlP is a promising catalyst to promote energy efficiency for nonaqueous Li-O2 and Na-O2 batteries.