Promoting defective-Li2O2 formation via Na doping for Li–O2 batteries with low charge overpotentials

Zhiyang Lyu; Tao Wang; Rui Guo; Yin Zhou; Junchao Chen; Xiao Wang; Ming Lin; XinXin Tian; Min Lai; Luming Peng; Li Wang; Zhangquan Peng; Wei Chen

doi:10.1039/C9TA01606F

Promoting defective-Li₂O₂ formation via Na doping for Li–O₂ batteries with low charge overpotentials†

Zhiyang Lyu,

‡*^ab Tao Wang,

‡^c Rui Guo,

‡^b Yin Zhou,

^b Junchao Chen,^d Xiao Wang,^d Ming Lin,

^e XinXin Tian,^f Min Lai,^a Luming Peng,^d Li Wang,

^g Zhangquan Peng^h and Wei Chen

*^bij

Author affiliations

* Corresponding authors

^a School of Physics and Optoelectronic Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, Jiangsu, China

^b Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore
E-mail: mselyuz@nus.edu.sg, phycw@nus.edu.sg

^c SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA

^d Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China

^e Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way. Innovis, Singapore

^f Institute of Molecular Science, Key Laboratory of Materials for Energy Conversion and Storage of Shanxi Province, Shanxi University, Taiyuan 030006, China

^g Department of Physics, Nanchang University, Nanchang, China

^h State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Science, Changchun, Jilin 130022, China

ⁱ Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore

^j National University of Singapore (Suzhou) Research Institute, Suzhou, China

Abstract

Li–O₂ batteries represent a promising candidate for next-generation energy storage systems because of their high specific energy density. However, one key limitation is their low energy efficiency, which is caused by the high charge overpotential owing to the sluggish oxidation kinetics of the insulating Li₂O₂ product. Here, we report an approach to reduce charge overpotentials by forming Na-doped defective Li₂O₂ in a Na⁺-added electrolyte, which is verified by systematic experimental characterization. Theoretical simulations reveal that the Na-doped Li₂O₂ with lithium vacancies exhibits new conducting states right above the valence band edge, thereby enhancing electron transport properties. The cell with the defective-Li₂O₂ product achieves a charge overpotential of ∼0.4 V, much lower than that of the cell with Li₂O₂ (∼1.1 V). This study offers an effective approach to promote Li₂O₂ decomposition by forming defective Li₂O₂.

Journal of Materials Chemistry A

Promoting defective-Li₂O₂ formation via Na doping for Li–O₂ batteries with low charge overpotentials†

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Promoting defective-Li₂O₂ formation via Na doping for Li–O₂ batteries with low charge overpotentials

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Journal of Materials Chemistry A