Improved ionic conductivity and air stability of Li7P3S11 by SnSe2 doping and two-step pressing sintering method

Abstract

The ideal solid-state electrolyte must possess high ionic conductivity and exceptional chemical and electrochemical stability. We prepared 70Li2S-(30 – x)P2S5-xSnSe2 (x = 0, 0.5, 1, 1.5, 2, 3) glass-ceramic electrolytes doped with SnSe2 using a facile high-energy ball milling combined with an annealing process. We utilized a “two-step pressing method” to eliminate defects such as voids generated during annealing. Through the use of X-ray powder diffraction (XRD) and energy-dispersive spectroscopy (EDS) mappings, we confirmed that a small amount of SnSe2 can be successfully and uniformly doped into the framework of the solid-state electrolyte. In particular, the 70Li2S-28.5P2S5–1.5SnSe2 (Li7P2.85Sn0.075S10.625Se0.15) glass-ceramic exhibits the highest conductivity of 2.62 × 10−3 S·cm−1 at room temperature, along with excellent electronic insulation and a stable -0.5 to 5 V (vs. Li/Li+) high-voltage platform. Furthermore, our combination of various methods, such as the LCR digital electric bridge, has proven that the doping of SnSe2 effectively enhances the chemical stability. Moreover, all-solid-state batteries assembled based on Li7P2.85Sn0.075S10.625Se0.15 electrolyte demonstrate enhanced rate capability and cycling stability. These results indicate that the Li7P2.85Sn0.075S10.625Se0.15 electrolyte can effectively construct high-performance all-solid-state batteries, facilitating industrial production and widespread adoption.