Chemistry Design Towards a Stable Sulfide-Based Superionic Conductor Li4 Cu8 Ge3 S12

Yingqi Wang; Xujie Lü; Chong Zheng; Xiang Liu; Zonghai Chen; Wenge Yang; Jianhua Lin; Fuqiang Huang

doi:10.1002/anie.201901739

Chemistry Design Towards a Stable Sulfide-Based Superionic Conductor Li₄ Cu₈ Ge₃ S₁₂

Angew Chem Int Ed Engl. 2019 Jun 3;58(23):7673-7677. doi: 10.1002/anie.201901739. Epub 2019 Apr 29.

Authors

Yingqi Wang¹, Xujie Lü¹, Chong Zheng², Xiang Liu³, Zonghai Chen³, Wenge Yang¹, Jianhua Lin⁴, Fuqiang Huang^{4

5}

Affiliations

¹ Center for High Pressure Science & Technology Advanced Research, Shanghai, 206203, P. R. China.
² Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL, 60115, USA.
³ Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
⁴ State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, P. R. China.
⁵ CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, P. R. China.

Abstract

Sulfide-based superionic conductors with high ionic conductivity have been explored as candidates for solid-state Li batteries. However, moisture hypersensitivity has made their manufacture complicated and costly and also impeded applications in batteries. Now, a sulfide-based superionic conductor Li₄ Cu₈ Ge₃ S₁₂ with superior stability was developed based on the hard/soft acid-base theory. The compound is stable in both moist air and aqueous LiOH aqueous solution. The electrochemical stability window was up to 1.5 V. An ionic conductivity of 0.9×10^-4 S cm with low activation energy of 0.33 eV was achieved without any optimization. The material features a rigid Cu-Ge-S open framework that increases its stability. Meanwhile, the weak bonding between Li⁺ and the framework promotes ionic conductivity. This work provides a structural configuration in which weak Li bonding in the rigid framework promotes an environment for highly conductive and stable solid-state electrolytes.

Keywords: chalcogenide open frameworks; crystal engineering; enhanced stability; solid electrolytes; superionic conductors.

Abstract

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