Computational study on catalytic performance of BC3 and NC3 nanosheets as cathode electrocatalysts for nonaqueous Li–O2 batteries

• Published in: Journal of power sources 2019-10, Vol.436, p.226845, Article 226845
• Main Authors: Zheng, Fangfang, Dong, Huilong, Ji, Yujin, Li, Youyong
• Format: Article
• Language: English
• Subjects: BC3 nanosheet; First-principles calculation; Li-O2 battery; NC3 nanosheet; Overpotential
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.226845

The development of high-performance cathode electrocatalysts in nonaqueous lithium-oxygen (Li–O2) battery is mainly restricted by high charge/discharge overpotentials. Based on first-principles calculations, we theoretically explore the application potential of BC3 and NC3 nanosheets as the suitable cathode electrocatalysts. By analyzing the stable adsorption configurations of LixO2y (x = 0–4, y = 0–2) intermediates on BC3/NC3, it is confirmed that oxygen reduction reaction (ORR) on BC3 follows four-electron pathway with (Li2O)2 as the discharge product, while for ORR on NC3, (Li2O2)2 is the discharge product following two-electron pathway. We then plot the corresponding free energy diagrams of charge/discharge processes and calculate the theoretical discharge and charge overpotentials (ηORR and ηOER) along the optimal reaction pathways. Our results show that both the ηORR and ηOER on BC3 are considerably low (0.21 V and 0.36 V), indicating that BC3 can serve as a high-performance cathode electrocatalyst. Meanwhile, the ηORR and ηOER on NC3 (0.37 V and 0.95 V) are comparable to previously reported materials following two-electron pathway (such as N-doped graphene), exhibiting practical values. Both the BC3 and NC3 nanosheets are stable enough for application in Li–O2 battery, and dimethyl sulfoxide (DMSO) isn't recommended as an organic electrolyte when BC3 works as the cathode catalyst. [Display omitted] •2D BC3 and NC3 are theoretically explored as cathode catalysts in Li–O2 battery.•The ORR pathway and discharge product vary with the cathode catalysts.•Both the ηORR (0.21 V) and ηOER (0.36 V) on BC3 are considerably low.•The ηORR (0.37 V) and ηOER (0.95 V) on NC3 are comparable to N-doped graphene.