Towards a Practical Use of Sulfide Solid Electrolytes in Solid‐State Batteries: Impact of Dry Room Exposure on H2S Release and Material Properties.

Sulfide‐based solid electrolytes (SEs) are amongst the most promising solid electrolytes for the development of solid‐state batteries (SSBs) due to their high ionic conductivity and processing advantage over oxide‐based SEs. However, one of the main drawbacks of sulfide SEs is their rapid degradation in presence of humidity. In this study, we investigated the effect of exposing three different sulfide SEs (Li7P3S11, the argyrodite Li6PS5Cl and the chloride‐doped argyrodite Li6‐xPS5‐xCl1+x) to the atmosphere of a dry room at a dew point (DP)=−40 °C. For the first time to the best of our knowledge, enhanced infra‐red (IR) laser technology was employed to follow and quantify online and in‐situ H2S evolution by the SEs in a dry room environment over 16 h. It was found that argyrodite compounds evolved approximately 8 times less H2S compared to Li7P3S11 over 16 h of exposure with peak concentrations between 5 and 16 ppm vol. The exposed materials were studied using X‐ray diffraction, Raman spectroscopy, electrochemical impedance spectroscopy, X‐ray photoelectron spectrometry (XPS) and galvanostatic cycling. XPS results revealed a formation of Li2CO3 on the surface of argyrodite SEs, which served as a robust passivation layer limiting considerably reactions with the dry room atmosphere. [ABSTRACT FROM AUTHOR]