B−N co-doped biphenylene is proposed as a promising metal-free cathode catalyst for Li−O₂ batteries, based on density functional theory calculations. Specially, the modeling results reveal that strengthening the Li−O bond reduces the overpotential during the discharge process, and that a moderate adsorption energy of *Li₂O₂ facilitates the charge process.

Abstract

Lithium-oxygen batteries (LOBs) meet the growing demand for long-distance transportation over electric vehicles but face challenges because of the lack of high-performance cathode catalysts. Herein, using density functional theory calculations, we report a unique graphene allotrope, biphenylene, of which the doping structures exhibit great potential as metal-free catalysts for LOBs. Our modeling results demonstrate that the biphenylene nanosheets retain metallic properties after B doping, N doping, or B−N co-doping. Compared with the pristine biphenylene, the catalytic activity of the doped biphenylene is greatly improved due to charge redistributions. Notably, the overpotentials of the B−N co-doped biphenylene are as low as 0.19 and 0.18 V for the discharge and charge processes, respectively. Based on the electronic structure and bonding analysis, we identify two factors, i. e., Li−O bond strength and *Li₂O₂ adsorption energy, that can influence the Li−O₂ electrochemical reactions. This study not only proposes a promising cathode catalyst but also provides insights into optimizing cathode catalysts for LOBs.