Rapid and Economic Synthesis of a Li₇PS₆ Solid Electrolyte from a Liquid Approach

Abstract

Solid electrolytes are the key to realize future solid-state batteries that show the advantages of high energy density and intrinsic safety. However, most solid electrolytes require long time and energy-consuming synthesis conditions of either extended ball milling or high-temperature solid-state reactions, impeding practical applications of solid electrolytes for large-scale systems. Here, we report a new and rapid liquid-based synthetic method for preparing a high-purity Li7PS6 solid electrolyte through the stoichemical reaction of Li3PS4 and Li2S. This method relies on facile and low-cost solution-based soft chemistry to complete chemical reaction in extensively short time (2 h). The prepared Li7PS6 solid electrolyte shows a high phase purity, an impressive ionic conductivity (0.11 mS cm–1), and a reasonable electrochemical stability with a metallic lithium anode. Our results highlight the use of an economic and nontoxic solvent to quickly synthesize a Li7PS6 solid electrolyte, which would promote the development of solid-state batteries for next-generation energy storage systems.

Wet‐Chemical Tuning of Li3−xPS4 (0≤x≤0.3) Enabled by Dual Solvents for All‐Solid‐State Lithium‐Ion Batteries

“…Since Liang and co‐workers synthesized nanoporous β‐Li 3 PS 4 (0.16 mS cm −1 ) by liquid‐phase synthesis, which is otherwise unobtainable by conventional synthetic methods (γ‐Li 3 PS 4 , >10 −6 S cm −1 ), extensive efforts in liquid‐phase synthesis and solution process have led to the identification and development of new materials, such as Li 7 P 2 S 8 I (0.6 mS cm −1 ), 0.4 LiI‐0.6 Li 4 SnS 4 (0.4 mS cm −1 ), and argyrodite high‐temperature phase Li 7 PS 6 (0.1 mS cm −1 ) . Furthermore, the wet‐chemical routes provide new potentially advantageous features of mass production and morphology/size control, and new opportunities for the fabrication of all‐solid‐state batteries, such as SE coating on active materials, SE‐infiltrated electrodes, and wet‐tailored electrodes …”

“…Adding excess sulfur for the liquid‐phase synthesis of Li 3 PS 4 allowed the conversion of the suspension into a homogeneous solution although the as‐obtained SE materials showed poor conductivities of <10 −5 S cm −1 . Argyrodites Li 6 PS 5 X and high‐temperature phase Li 7 PS 6 were successfully synthesized from homogeneous solutions acquired from their precursors by using dual solvents (THF (or ethyl propionate or acetonitrile) and ethanol) . A recent investigation on the synthesis of Li 7 P 3 S 11 by using acetonitrile pointed out the importance of soluble species Li 2 S‐P 2 S 5 .…”

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.…”

Synthesis and Properties of NaSICON‐type LATP and LAGP Solid Electrolytes

“…Suc-cessfule xamples in oxidesi nclude garnet oxides, [15,16] perovskite-type oxides, [17,18] and antiperovskite oxides. [29][30][31] Popular phosphate solid electrolytes include sodium superionic conductor (NaSICON)structured lithium-ion conductors, [32][33][34][35][36] such as LiTi 2 (PO 4 ) 3 (LTP), Li 1 + x Al x Ti 2Àx (PO 4 ) 3 (LATP), and Li 1 + x Al x Ge 2Àx (PO 4 ) 3 (LAGP). [29][30][31] Popular phosphate solid electrolytes include sodium superionic conductor (NaSICON)structured lithium-ion conductors, [32][33][34][35][36] such as LiTi 2 (PO 4 ) 3 (LTP), Li 1 + x Al x Ti 2Àx (PO 4 ) 3 (LATP), and Li 1 + x Al x Ge 2Àx (PO 4 ) 3 (LAGP).…”

“…[19][20][21] Sulfide solid electrolytes include Li 2 SÀP 2 S 5 , [22,23] Li 3 PS 4 , [24][25][26] Li 7 P 3 S 11 , [27,28] Li 7 PS 6 ,a nd Li 6 PS 5 X( X = Cl, Br). [29][30][31] Popular phosphate solid electrolytes include sodium superionic conductor (NaSICON)structured lithium-ion conductors, [32][33][34][35][36] such as LiTi 2 (PO 4 ) 3 (LTP), Li 1 + x Al x Ti 2Àx (PO 4 ) 3 (LATP), and Li 1 + x Al x Ge 2Àx (PO 4 ) 3 (LAGP). Many exciting discoveries of these materials have been summarized in important review papers.…”