Influence of Solid Fraction on Particle Size during Wet-Chemical Synthesis of β-Li3PS4 in Tetrahydrofuran

Abstract

For all-solid-state batteries, the particle size distribution of the solid electrolyte is a critical factor. Small particles are preferred to obtain a high active mass loading of cathode active material and a small porosity in composite cathodes. In this work, the influence of the solid fraction in the wet-chemical synthesis of β-Li3PS4 in tetrahydrofuran (THF) is investigated. The solid fraction is varied between 50 and 200 mg/mL, and the obtained samples are evaluated using X-ray diffraction, SEM and electrochemical impedance measurements. The sizes of the resulting particles show a significant dependency on the solid fraction, while a good ionic conductivity is maintained. For the highest concentration, the particle sizes do not exceed 10 µm, but for the lowest concentration, particles up to ~73 µm can be found. The ionic conductivities at room temperature are determined to be 0.63 ± 0.01 × 10−4 S/cm and 0.78 ± 0.01 × 10−4 S/cm for the highest and lowest concentrations, respectively. These findings lead to an improvement towards the production of tailored sulfide solid electrolytes.

Evaluation of Various Solvents for the Wet-Chemical Synthesis of β-Li3PS4 under Energy and Environmental Aspects

“…A significant change in morphology compared to using THF (Figure S1) is evident. Neither block-like particles 8,17 nor octagonal prisms 17 are visible. The influence of different solvents on morphology is known in the literature 38,47−50 and can be deliberately used to synthesize specific morphologies.…”

“…14 Moreover, scaling up a wetchemical synthesis is generally considered easier compared to high-temperature solid-state reactions 11,14,15 and opens up the ability to control particle sizes. 16,17 In a study by Liu et al, 8 the wet-chemical synthesis route to stabilize β-Li 3 PS 4 at room temperature was established. For this, the starting materials were stirred overnight in THF, followed by centrifugation and solvent removal.…”

“…The wet-chemical synthesis offers advantages over the mechanical ball-milling routine , and the solid-state reaction , such as short reaction times and realization at low temperatures . Moreover, scaling up a wet-chemical synthesis is generally considered easier compared to high-temperature solid-state reactions ,, and opens up the ability to control particle sizes. , …”