Synthesis and characterization of Na3PS4 and Na 2.85 P 0.85 W 0.15 S 4 as solid electrolytes

International audience ; The next generations of postlithium systems are already under development. These hold the promise of overcoming some of the remaining challenges associated with current lithium-ion battery technology related to safety, the need for scarce resources and their environmental impacts. Na₃PS₄ (NPS) is a sodium superionic conductor that crystallizes in the I-43m space group and reaches ionic conductivities in the range of the mS/cm. • X-ray diffractograms show a cubic crystalline phase of Na3PS4 and a mixture of Na3PS4 and WS2 for the Na2.85P0.85W0.15S4 sample.• SEM-EDX results confirmed that a reaction occurs between the sample holder (Macor®) and the solid electrolytes during the heat treatments.• Electrochemical results show that a heat treatment under Ar slightly improves the ionic conductivity for the NPS sample, while the HTs in presence of Macor® spacer turn the materials into ionic insulants.