title: Electrolyte-controlled discharge product distribution of Na-O2batteries: a combined computational and experimental study.
abstract: Tuning the composition of discharge products is an important strategy to reduce charge potential, suppress side reactions, and improve the reversibility of metal-oxygen batteries. In the present study, first-principles calculations and experimental confirmation were performed to unravel the influence of O2pressure, particle size, and electrolyte on the composition of charge products in Na-O2batteries. The electrolytes with medium and high donor numbers (>12.5) are favorable for the formation of sole NaO2, while those with low donor numbers (<12.5) may permit the formation of Na2O2by disproportionation reactions. Our comparative experiments under different electrolytes confirmed the calculation prediction. Our calculations indicated that O2pressure and particle size hardly affect discharge products. On the electrode, only one-electron-transfer electrochemical reaction to form NaO2takes place, whereas two-electron-transfer electrochemical and chemical reactions to form Na2O2and Na3O4are prevented in thermodynamics. The present study explains why metastable NaO2was identified as a sole discharge product in many experiments, while thermodynamically more stable Na2O2was not observed. Therefore, to achieve low overpotential, a high-donor-number electrolyte should be applied in the discharge processes of Na-O2batteries.
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn and Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Beizhou
authors.identifier: http://orcid.org/0000-0002-3783-803X
authors.initials: B
authors.lastname: Wang
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn.
authors.forename: Youwei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn and Materials Genome Institute, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, P. R. China.
authors.forename: Wencong
authors.initials: W
authors.lastname: Lu
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn.
authors.forename: Xiangxin
authors.initials: X
authors.lastname: Guo
authors.affiliation: State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, P. R. China. jliu@mail.sic.ac.cn xxguo@mail.sic.ac.cn.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Liu