In the synthesis of sulfide-halide solid-state electrolytes—most notably lithium argyrodites (such as Li6PS5Br) and halide-doped glass-ceramics (like Li7P3S11 * LiBr)—lithium bromide (LiBr) serves as a critical dopant precursor. Integrating LiBr into a pure sulfide framework expands the polarizable anion lattice, creates beneficial lithium-ion vacancies, and optimizes the local structural disorder, pushing the room-temperature ionic conductivity of the electrolyte toward or beyond 10^{-3} S cm-1.

Compared to transition metal chlorides like ZrCl4, LiBr is thermally stable and will not sublime or volatilize at typical synthesis temperatures. However, its primary challenge is an extreme susceptibility to moisture. (1) Purity Requirements: Standard protocols demand 99.9% (3N) or 99.99% (4N) anhydrous grade (trace metals basis). Impurities like sodium or heavy metals can compromise the electrochemical window or induce unwanted electronic leakage. (2) Extreme Hygroscopicity: LiBr is significantly more hygroscopic than LiCl. Upon even brief exposure to trace moisture, it quickly forms hydrates (LiBr *H2O). (3) Crucial Dehydration Protocol: Commercial "anhydrous" LiBr often contains bound surface moisture. To prevent the irreversible formation of insulating lithium oxide (Li2O) or phase degradation during synthesis, LiBr should be dried under a deep vacuum (10^{-2} Torr or better) at 200°C to 300°C for 12–24 hours before weighing inside the glovebox.

Notes: (1) Please store the LiBr powder in a dry place (glovebox is preferred due to its air/humidity sensitivity).

References: 

1. P. Lannelongue, et al. Stable cycling of halide solid state electrolyte enabled by a dynamic layered solid electrolyte interphase between Li metal and Li3YCl4Br2, Energy Storage Materials, 2024, 72, 103733.
2. T. P. Poudel, et al. Transforming Li3PS4 Via Halide Incorporation: a Path to Improved Ionic Conductivity and Stability in All-Solid-State Batteries, Adv Fucnt. Materi., 2024, 34, 2309656