Design principles for NASICON super-ionic conductors

Jingyang Wang; Tanjin He; Xiaochen Yang; Zijian Cai; Yan Wang; Valentina Lacivita; Haegyeom Kim; Bin Ouyang; Gerbrand Ceder

doi:10.1038/s41467-023-40669-0

Design principles for NASICON super-ionic conductors

Nat Commun. 2023 Aug 25;14(1):5210. doi: 10.1038/s41467-023-40669-0.

Authors

Jingyang Wang^{1

2

3}, Tanjin He^{1

2}, Xiaochen Yang^{1

2}, Zijian Cai^{1

2}, Yan Wang⁴, Valentina Lacivita⁴, Haegyeom Kim¹, Bin Ouyang⁵, Gerbrand Ceder^{6

7}

Affiliations

¹ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
² Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.
³ School of Sustainable Energy and Resources, School of Materials Science and Intelligent Engineering, Nanjing University, Suzhou, China.
⁴ Advanced Materials Lab, Samsung Advanced Institute of Technology and Samsung Semiconductor, Inc, Cambridge, MA, 02138, USA.
⁵ Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL, 32306, USA. bouyang@fsu.edu.
⁶ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. gceder@berkeley.edu.
⁷ Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA. gceder@berkeley.edu.

Abstract

Na Super Ionic Conductor (NASICON) materials are an important class of solid-state electrolytes owing to their high ionic conductivity and superior chemical and electrochemical stability. In this paper, we combine first-principles calculations, experimental synthesis and testing, and natural language-driven text-mined historical data on NASICON ionic conductivity to achieve clear insights into how chemical composition influences the Na-ion conductivity. These insights, together with a high-throughput first-principles analysis of the compositional space over which NASICONs are expected to be stable, lead to the successful synthesis and electrochemical investigation of several new NASICONs solid-state conductors. Among these, a high ionic conductivity of 1.2 mS cm^-1 could be achieved at 25 °C. We find that the ionic conductivity increases with average metal size up to a certain value and that the substitution of PO₄ polyanions by SiO₄ also enhances the ionic conductivity. While optimal ionic conductivity is found near a Na content of 3 per formula unit, the exact optimum depends on other compositional variables. Surprisingly, the Na content enhances the ionic conductivity mostly through its effect on the activation barrier, rather than through the carrier concentration. These deconvoluted design criteria may provide guidelines for the design of optimized NASICON conductors.