Discovery of inorganic glass electrolytes with polymer-like viscoelasticity

Solid-state batteries offering both high energy density and safety have aroused widespread interest as promising power sources for electric vehicles. However, the interfacial mechanical stability of inorganic electrolyte is inferior to that of organic electrolytes and the high stack pressure (several to hundreds of megapascals) is required to maintain the intimate contact with electrodes. Here we report a class of inorganic glass solid electrolytes with polymer-like viscoelasticity, which possess both advantages of inorganic and polymer electrolytes and can enable pressure-less Li- and Na-based solid-state batteries (< 0.1 MPa). These electrolytes are synthesized by simply replacing chlorine of tetrachloroaluminates with oxygen, demonstrating high ionic conductivity of ~1 mS cm -1 at 30℃ for both Li + and Na + . They can also exhibit superior chemo-mechanical compatibility with 4.3 V cathodes without additional stack pressure. Moreover, the inorganic glass solid electrolytes are feasible for scale-up, not only enabling to be made into thin films through a rolling process owing to its polymer-like flexibility but also facilitating the complete infiltration of the electrode materials like a liquid battery due to the low melting temperature below 160℃. We believe that these viscoelastic inorganic solid electrolytes will inspire us to design new solid electrolytes and accelerate practical application of pressure-less solid-state batteries.