Incorporation of lithium halogen in Li7P3S11 glass-ceramic and the interface improvement mechanism.

• The influence of halogens incorporation on Li 7 P 3 S 11 glass-ceramic is studied. • 80Li 7 P 3 S 11 •20LiBr shows improved ability to suppress lithium dendrites. • LiBr does not enter the lattice, but rather exists in the lattice gap of Li 7 P 3 S 11. • Br decrease electron cloud density on P and S , reduce Li+ binding and increase ion conductivity. • DFT evaluations prove that LiBr incorporation increases interface energy of SEI to Li. Li 7 P 3 S 11 glass-ceramic is considered as a superionic conductor electrolyte with great application prospect, but its realization is limited due to an unstable interface against lithium metal. Incorporation of lithium halides in electrolyte promotes enhancement in ionic conductivity and helps inhibit lithium dendrite growth. However, the mechanistic impact of halide incorporation is still not been fully explained. In this work, the effects of halogen introduction into Li 7 P 3 S 11 glass-ceramic to the ion conductivity, critical current density and interfacial stability of solid electrolyte interphase (SEI) is studied. It shows that the LiBr-incorporated Li 7 P 3 S 11 obtains the most obviously increased critical current density. Structural characterizations indicate that the LiBr does not enter the lattice, but rather exists in the lattice gap of Li 7 P 3 S 11. However, the highly electronegative Br decreases the electron cloud density on the surface of P 2 S 7 4− and PS 4 3− units, reduces their binding to Li+ and thus increases the ion conductivity. Density functional theory evaluations show that the addition of LiBr can increase the interface energy of SEI to Li, which is beneficial to suppress the growth of lithium dendrite. Therefore, the Li/80Li 7 P 3 S 11 •20LiBr/Li cell presents a double increase of the critical current density (0.968 mA/cm2) and circulates stably at 0.5 mA/cm2 at room temperature. The effects of halogen introduction into Li 7 P 3 S 11 glass-ceramic to the ion conductivity and interfacial stability of SEI is studied. [Display omitted] [ABSTRACT FROM AUTHOR]