Materials Design Principles for Air‐Stable Lithium/Sodium Solid Electrolytes

Abstract

Sulfide solid electrolytes are promising inorganic solid electrolytes for all‐solid‐state batteries. Despite their high ionic conductivity and desirable mechanical properties, many known sulfide solid electrolytes exhibit poor air stability. The spontaneous hydrolysis reactions of sulfides with moisture in air lead to the release of toxic hydrogen sulfide and materials degradation, hindering large‐scale manufacturing and applications of sulfide‐based solid‐state batteries. In this work, we systematically investigate the hydrolysis and reduction reactions in Li‐ and Na‐containing sulfides and chlorides by applying thermodynamic analyses based on a first principles computation database. We reveal the stability trends among different chemistries and identify the effect of cations, anions, and Li/Na content on moisture stability. Our results identify promising materials systems to simultaneously achieve desirable moisture stability and electrochemical stability, and provide the design principles for the development of air‐stable solid electrolytes.

A cost-effective and humidity-tolerant chloride solid electrolyte for lithium batteries

“…Therefore, the conductivity of the as-milled LZC should be considered largely unchanged after humidity exposure. Clearly, in the atmosphere with 5% relative humidity, LZC shows better stability than Li 3 InCl 6 , even though the latter is considered the most humidity tolerant chloride system in literature 8,41 . Since LZC is truly moisture resistant and thus does not need to be recovered after humidity exposure, the environment for its manufacturing and storage does not necessarily possess the low dew point that is typically required by sulfide solid electrolytes.…”

“…With such advantage in cost-effectiveness, Li 2 ZrCl 6 not only preserves the desirable properties of other chloride solid electrolytes, e.g., high ionic conductivity (0.81 mS cm -1 ), deformability, excellent compatibility with 4V-class cathodes, etc., but also displays a unique stability against moisture. After being exposed to the atmosphere with 5% relative humidity, Li 2 ZrCl 6 undergoes neither moisture uptake nor conductivity degradation, while Li 3 InCl 6 , i.e., the chloride system considered most humidity tolerant in literature 8,41 , partially becomes Li 3 InCl 6 •2H 2 O and shows significantly decreased conductivity under the same condition.…”

Polymer-based hybrid battery electrolytes: theoretical insights, recent advances and challenges

“…Li 3 PS 4 , Li 6 PS 5 Cl, and Li 10 -GeP 2 S 12 (LGPS), release H 2 S gas upon moisture exposure; therefore, any exposure to ambient air and residual moisture needs to be avoided. 143 Phosphorous reduction and sulfur oxidation restrict the electrochemical stability window, oen requiring a carefully tuned potential window for mitigating the evolution of interfacial resistances. [144][145][146] Indeed, Li 10 SnP 2 S 12 has recently shown to be unstable with PEO-LiTFSI electrolyte.…”

Preparation and electrochemical properties of ionic-liquid-modified Na3SbS4 membrane composite electrolytes

“…The poor interface compatibility between electrolyte and Na metal is one of the major challenges for sulfide SEs. The decomposed interphases with high electronic conductivity deteriorate the interface and continuously increase the overpotential and irreversible capacity loss, thereby seriously damaging the cycling performance of the batteries [11][12][13]. The methods commonly applied to mitigate this issue are as follows.…”