A Lithium Oxythioborosilicate Solid Electrolyte Glass with Superionic Conductivity

Abstract

As potential next‐generation energy storage devices, solid‐state lithium batteries require highly functional solid state electrolytes. Recent research is primarily focused on crystalline materials, while amorphous materials offer advantages by eliminating problematic grain boundaries that can limit ion transport and trigger dendritic growth at the Li anode. However, simultaneously achieving high conductivity and stability in glasses is a challenge. New quaternary superionic lithium oxythioborate glasses are reported that exhibit high ion conductivity up to 2 mS cm−1 despite relatively high oxygen: sulfur ratios of more than 1:2, that exhibit greatly reduced H2S evolution upon exposure to air compared to Li7P3S11. These monolithic glasses are prepared from vitreous melts without ball‐milling and exhibit no discernable XRD pattern. Solid‐state NMR studies elucidate the structural entities that comprise the local glass structure which dictates fast ion conduction. Stripping/plating onto lithium metal results in very low polarization at a current density of 0.1 mA cm−2 over repeated cycling. Evaluation of the optimal glass composition as an electrolyte in an all‐solid‐state battery shows it exhibits excellent cycling stability and maintains near theoretical capacity for over 130 cycles at room temperature with Coulombic efficiency close to 99.9%, opening up new avenues of exploration for these quaternary compositions.

Sulfide and Oxide Inorganic Solid Electrolytes for All-Solid-State Li Batteries: A Review

“…Moreover, owing to its synthesis temperature being similar to that of the cathode, this electrolyte could be useful for the preparation of ASSB oxide/sulfide composite electrolytes. Kaup et al [237] studied 30Li2S-25B2S3-45LiI-xSiO2 (Li1.05B0.5SixO2xS1.05I0.45) (0 ≤ x ≤ 1) quaternary superionic Li oxythioborate glasses. The prepared compositions presented negligible H2S evolution on pellets upon exposure to ambient air and a stable capacity of 230 mAh g −1 up to 230 cycles, at a rate of 0.1C when paired with a TiS2 intercalation cathode (Figurea 14a, 14b and 14c).…”

“…(c) cycling data at 60 °C at a rate of 1C. Reproduced with permission from[237]. Copyright 2020 Wiley.…”

NMR Investigations of Crystalline and Glassy Solid Electrolytes for Lithium Batteries: A Brief Review

“…Additionally, the ionic conductivity of LIBOSS peaks at a silica content of 0.25 (2 mS/cm), but decreases and remains steady at higher x, until dropping at x = 0.75, when the LiI crystallizes. xSiO2-zLiI (LIBOSS) with varying silica content [11]. 11 B and 29 Si MAS NMR, as seen in figure 3, were utilized to elucidate this trend.…”

“…xSiO2-zLiI (LIBOSS) with varying silica content [11]. 11 B and 29 Si MAS NMR, as seen in figure 3, were utilized to elucidate this trend. The 11 B spectra of the x = 0 sample revealed the presence of multiple boron-containing tetrahedral units, such as BO3, BO2S, BS3, and BS4 [12,13].…”

“…This is seen in the 29 Si spectra, with the presence of two peaks at 7 ppm and -4.5 ppm, corresponding to SiS4 and SiOS3 units, respectively. (Top) Activation energy and (bottom) room temperature ionic conductivity of aLi 2 S-γB 2 S 3 -xSiO 2 -zLiI (LIBOSS) with varying silica content [11].…”