Influence of precipitate/supernatant ratio during liquid-phase synthesis of solid electrolyte Li7P3S11

Abstract

Delicate control of the precipitate/supernatant ratio in the precursor suspension during liquid-phase synthesis of Li7P3S11 provides information on how the morphology of the impurities affect the ionic conductivity. In this work, the influence of the precipitate/supernatant ratio on the phase structure, the morphology and the ionic conductivity of Li7P3S11 prepared in acetonitrile is studied. It is revealed that in the supernatant-excess region, the excess amorphous "Li2S•P2S5" finally turns into a poorly ionic conductive phase Li4P2S6 which wraps Li7P3S11 particles, increasing the interfacial resistance. In the precipitate-excess region, a thio-LISICON III phase turned from the excess precipitate tends to stay within Li7P3S11 particles, and therefore its negative influence on the total ionic conductivity is not evident. Consequently, a slight composition shift into the precipitate-excess region benefits the ionic conductivity of the resultant solid electrolyte.

Will Sulfide Electrolytes be Suitable Candidates for Constructing a Stable Solid/Liquid Electrolyte Interface?

“…An intense 388 cm –1 peak appears in the immersed Li 7 P 3 S 11 , indicating that, besides the crystalline DME-solvated Li 3 PS 4 , an amorphous phase containing vertex-shared PS 4 tetrahedral anions exists. Recent studies on liquid-phase synthesis of Li 7 P 3 S 11 in acetonitrile reveal that the starting materials Li 2 S and P 2 S 5 react with crystalline Li 3 PS 4 ·ACN and amorphous “Li 2 S·P 2 S 5 ” phases in the solvent, where the Li 2 S·P 2 S 5 phase is constituted by vertex-shared PS 4 tetrahedral anions, whose major Raman signal is at 383 cm –1 . It is therefore proposed to assign this amorphous immersion product of Li 7 P 3 S 11 to an ether-solvated Li 2 S·P 2 S 5 phase.…”

“…Differently, the solvated "Li2S•P2S5" phase is soluble or partially soluble in polar solvents due to the more scattered charge density of its vertex-shared PS4 tetrahedral anions and therefore the weaker ionic bond with Li + ions. 48 As discussed above, Li7P3S11 is decomposed by the ether solvent into solvated Li3PS4 and "Li2S•P2S5". The gradual dissolution of "Li2S•P2S5" results in pinholes in the interphase layer which provide pathways for continuous reaction between Li7P3S11 and the solvent.…”

Solution Processing via Dynamic Sulfide Radical Anions for Sulfide Solid Electrolytes

“…The ionic conductivity varies by one order of magnitude, even when the manufacturing conditions are only slightly different. [10,12,13,20,[41][42][43][44] This fact indicates that the conventional methods involve difficulty in achieving intrinsic high conductivity for Li 7 P 3 S 11 during large-scale manufacturing. Our solution processing technology dramatically reduces the processing time for the wet-chemical reaction from 24 to 72 h in conventional liquid-phase synthesis to %2 min, leading to improved producibility, cost, scalability, and performance compared to the SEs produced by conventional methods.…”

Impact of Solvent Treatment of the Superionic Argyrodite Li6PS5Cl on Solid‐State Battery Performance

“…[ 2–4,7 ] Nevertheless, for commercial production of ASSBs, scalable synthesis and processing routes for the SE are crucial. Liquid‐phase synthesis has thus gained interest in recent years, [ 8–13 ] as well as solvent‐based processing of the electrolyte into separators, [ 14–17 ] or finished cathode composites. [ 3,5 ] This is either done as a slurry process (where the electrolyte is not dissolved) for mixing or as an infiltration/coating process (where the electrolyte is dissolved), with the benefit of allowing for intimate contact of the materials.…”