Derivatives of Na-thioantimonate as solid electrolytes for all-solid-state batteries

Laboratoire de Réactivité et Chimie des Solides (LRCS) / Amiens

Laboratoire de Physico-Chimie de l’Atmosphère (LPCA) / Dunkerque

Today, the most competitive and reliable technology used in electrochemical storage systems is based on lithium (Li) and the use of ionic conductive liquids. Considering the rising cost of lithium raw materials, the risks associated with their supply (abundance, geographical localization…) and the use of flammable liquids, it is necessary to find and offer alternatives involving other metal components and greater safety. Sodium (Na)-ion allsolid-state batteries (Na-ASSBs) are seen as an interesting option, combining a more abundant, and cheaper element with the use of a solid ionic conductor (non-flammable)1 . Sulphur-based compounds are promising solid electrolytes. They are ductile, enabling good cold-pressed electrolyte/electrode contacts, and highly conductive. Among them, compounds based on the Na3PnCh4 formula, with Pn and Ch as pnictogen and chalcogen elements, attract attention2 . With phosphorus (P, element Pn) and sulphur (S, element Ch), sodium tetrathiophosphate Na3PS4 is probably the most studied Na-solid electrolyte (ionic conductivity around 10-4 S/cm). A great deal of research has gone into improving it, including doping and iso/alio-valent substitutions on both the Pn and Ch sites3 . A remarkable development in this field has been the design of sodium thioantimonate Na3SbS4 with a conductivity of 1.1 x 10-3 S/cm, a low activation energy of 0.20 eV and good moisture stability4 , unlike Na3PS4. To date, few studies have been carried out on Na3SbS4 derivatives. The current project aims to explore NaSbS2 and Na3SbS4 phases by attempting to replace antimony (Sb) with bismuth (Bi, pnictogen element) in order to prepare NaSb1-xBixS2 or Na3(+2x)Sb1-xBixS4-type phases. Bismuth has never yet been proposed as substitute. The targeted materials will be synthesized by mechanochemistry and characterized in detail by various structural, microstructural and electrochemical techniques.

We wish to hire a highly motivated Master student with skills in inorganic chemistry and interest in synthesis. Please provide Curriculum vitae and motivation letter.