Tuning the moisture stability of multiphase β‐Li3PS4 solid electrolyte materials

Abstract

Abstract Efficiently improving the moisture stability of β‐Li3PS4 materials could significantly reduce production costs and eventually enable the mass application. Nanoporous multiphase β‐Li3PS4 materials prepared via solvent‐assistant routes usually contain solvent or solvent decomposition segments associated with the amorphous Li3PS4 phase in their structures. Herein, the solvent ethyl propionate (EP) remains in the β‐Li3PS4 even after 220 h of annealing at 220°C. The possibility of tuning the moisture stability of β‐Li3PS4 by adjusting the content of the solvent is investigated by environmental scanning electron microscopy (ESEM) combined with other structural analysis techniques. The results demonstrated that the hydrogen‐containing amorphous Li3PS4 not only stabilizes the β‐phase at room temperature but also improves the moisture stability of the material. Although the rapid hydrolysis occurs on the surface of solvent‐containing β‐Li3PS4 materials under ambient conditions within 10 s, with 4 wt% EP content, the material can be exposed to 1.6% relative humidity (R.H.) for at least 8 h without any structural or microstructural change. Even with the lower amount of EP (1.2 wt%) in the Li3PS4 structure, the material can withstand 1% R.H. for more than 8 h, which allows the material to be manufactured in a dry room. Our observation proposes a simple method to slightly modify the moisture stability of β‐Li3PS4 to match the different manufacturing conditions.

Keywords

• ambient stability
• microstructure
• moisture stability
• solvent‐containing Li3PS4
• β‐Li3PS4