Abstract
Understanding the differences in the structures and defects in the stable crystalline phase and metastable phase is important for increasing the ionic conductivities of a solid electrolyte. The metastable phase often has higher conductivity than the stable phase. In this study, metastable lithium thiogallate, Li5GaS4, was synthesized via mechanochemistry and stable Li5GaS4 was obtained by heating the metastable phase. The metastable Li5GaS4 sample was found to have an antifluorite-type crystal structure with cationic disorder, while the stable phase was found to have a monoclinic crystal structure, similar to that of another solid electrolyte, Li5AlS4. In both the structures, the Ga3+ cations were surrounded by four S2− anions in tetrahedral coordination. The conductivity of the metastable phase was determined to be 2.1 × 10−5 S cm−1 at 25 °C, which is 1000 times greater than that of the monoclinic phase. The high conductivity of the metastable phase was achieved owing to cation disorder in the crystal structure.
Highlights
Solid electrolytes, one of the key materials for realizing all-solidstate batteries, are required to have high ionic conductivity, suitable deformability, and high chemical/electrochemical stability
The solid electrolyte, milled Li5GaS4 was prepared by a mechanochemical process
A detailed analysis of the metastable crystal phase is difficult because of the broad X-ray diffraction (XRD) peaks, the observed XRD peaks can be attributed to a new metastable phase with the anti uorite-type crystal structure, which has eight tetrahedral sites for the cation surrounded by four anions in a unit cell
Summary
One of the key materials for realizing all-solidstate batteries, are required to have high ionic conductivity, suitable deformability, and high chemical/electrochemical stability. Sul de electrolytes have better deformability for densi cation than oxide electrolytes.[3] So far, various sul des, such as Li2S–P2S5 glass-based electrolytes,[4,5,6,7,8,9] thio-LISICON-type crystals,[10,11,12,13,14] Li10GeP2S12-type crystals,[1,2,15,16] and argyrodite-type crystals,[17,18,19,20] have been reported as solid electrolytes These solid electrolytes have been prepared with a wide range of compositions. When the 70Li2S$30P2S5 glass is heated to 240 C, the superionic conductive phase of Li7P3S11 precipitates as a metastable phase in the amorphous matrix.[6,8,22]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
