Anion and cation co-doping of Na4SnS4 as sodium superionic conductors. (December 2020)

• Record Type: Journal Article
• Authors: Xiong, Shan; Liu, Zhantao; Yang, Lufeng; Ma, Yifan; Xu, Wenqian; Bai, Jianming; Chen, Hailong
• Is Part Of: Materials today physics. Volume 15(2020)
• Publication Date: 2020-12
• Subjects: Solid electrolyte -- Solid-state battery -- Sodium superionic conductor -- Sulfide; Materials science -- Periodicals; Physics -- Periodicals; Electronic journals; 530.41
• DOI: 10.1016/j.mtphys.2020.100281
• Languages: English
• ISSNs: 2542-5293

Abstract

Abstract: Na based all-solid-state batteries are one of the most promising candidates for large-scale electrochemical energy storage owing to their low cost and outstanding safety properties. The key enabler of this technology is solid electrolyte with sufficiently high ionic conductivity at room temperature. In this work, the design, synthesis, characterization, and testing of a series of novel fast Na-ion conductors, Na4-x-y Sn1-x Ax S4-y Xy with aliovalent cation (P 5+ /Sb 5+ ) and anion (Cl − /Br − ) substitutions of the parent compound Na4 SnS4 are reported. The doped samples crystalize in a new phase with space group I 4 1 / acd and show ionic conductivities that are one to four orders of magnitude higher than that of undoped Na4 SnS4 . R. t. conductivity of 0.64 mS cm −1 is achieved in Na3.7 Sn0.8 Sb0.2 S3.9 Cl0.1 with a low activation energy of 0.26 eV. Rietveld refinement against high resolution synchrotron X-ray powder diffraction data reveals that the distribution of the doping ions and the resulted Na vacancies are underlying causes of the enhanced conductivity. Graphical abstract: Image 1 Highlights: Aliovalent doping of Na4 SnS4 with cation and anion dopants formed Na4-x-y Sn1-x Ax S4-y Xy compounds with new crystal structure. Na4-x-y Sn1-x Ax S4-y Xy compounds show up to four orders of magnitude higher r. t. ionic conductivities than Na4 SnS4 . Anion and cation co-doping better stabilizes the crystal structure than sole-anion doping. Na vacancies created by co-doping boosts the conductivity in Na4-x-y Sn1-x Ax S4-y Xy compounds.