Water-Stable Sulfide Solid Electrolyte Membranes Directly Applicable in All-Solid-State Batteries Enabled by Superhydrophobic Li+-Conducting Protection Layer

Sulfide solid electrolytes (SEs) represent one most promising technical routes to realize all-solid-state batteries (ASSBs) due to their high ionic conductivity and low mechanical stiffness. However, the poor air/moisture/water stability of sulfide SEs leads to completely destroyed structure/composition, reduced Li+ conductivity, and toxic H2S release, limiting their practical application in ASSBs. To solve this problem, a universal method applicable to all types of sulfide SEs is developed to realize water-stable sulfide SE membranes, by spray coating a Li+-conductive superhydrophobic protection layer with Li1.4Al0.4Ti1.6(PO4)(3) (LATP) nanoparticles and fluorinated polysiloxane (F-POS) via hydrolysis and condensation of tetraethyl orthosilicate and 1H,1H,2H,2H-perfluorodecyltriethoxysilane molecules. The F-POS@LATP coating layer exhibits excellent superhydrophobicity (water static contact angles > 160 degrees) to resist extreme exposure (direct water jetting), because of its micro-/nanoscale roughness and low surface energy. Moreover, ASSBs using the extreme-condition-exposed modified Li6PS5Cl membrane exhibit a reversible capacity of 147.3 mAh g(-1), comparable with the ASSBs using pristine sulfide membranes. The superhydrophobic Li+-conducting layer is demonstrated to be an effective protection method for sulfide membranes so that they remain stable and functionable in extreme water exposure conditions, providing a new approach to protect all types of sulfide SEs and other air/moisture/water-sensitive materials without sacrificing electrochemical performance.

Automated summary

A universal method was developed to create water-stable sulfide solid electrolyte membranes through spray coating a Li+-conductive superhydrophobic protection layer, which demonstrates excellent superhydrophobicity and maintains high electrochemical performance even under extreme water exposure conditions.