Synthesis and characterization of argyrodite solid electrolytes for all-solid-state Li-ion batteries

Abstract

Li 6 PS 5 X (X = Cl, Br, I) argyrodites possess high ionic conductivity but with rather scattered values due to various processing conditions. In this work, Li 6 PS 5 X solid electrolytes were prepared by solid-state sintering or mechanical alloying and optimized with or without excess Li 2 S. Solid-state sintering prefers excess Li 2 S, whereas mechanical alloying prefers stoichiometric Li 2 S to synthesize high-purity samples with high ionic conductivity. Solid-state sintering is also more suitable than mechanical milling for high ionic conductivity. Li 6 PS 5 Cl with the highest ionic conductivity among Li 6 PS 5 X was comprehensively characterized for electrochemical performance and air stability. MoS 2 /Li 6 PS 5 Cl all-solid-state batteries assembled with Li 6 PS 5 Cl-coated MoS 2 as cathode and with Li 6 PS 5 Cl as solid electrolyte demonstrate high capacity and good cycling stability.

Sulfide‐Based Solid‐State Electrolytes: Synthesis, Stability, and Potential for All‐Solid‐State Batteries

“…Thus ball‐milling provides more possibilities to prepare new amorphous glassy materials. Most sulfide glass conductors can be produced by ball‐milling, and crystalline phases can be achieved by mixing and consecutive annealing step . Ball‐milling has also been employed to mix sulfide SSEs with organic polymers, which produces a mixture of well‐dispersed polymers without breaking their organic chains …”

“…For instance, clear impurity peaks in the XRD pattern were observed after Li 6 PS 5 Cl electrolyte were exposed to air for 10 min. And the ionic conductivity degraded from 1.8 × 10 −3 S cm −1 for the pristine material to 1.56, 1.43, and 0.87 × 10 −3 S cm −1 after the material was exposed to air for 10 min, 1 h, and 24 h, respectively …”

Building Better Batteries in the Solid State: A Review

“…Li 6 PS 5 X ( X = Cl, Br, I) argyrodites exhibit a very high ionic conductivity of 2.58 × 10 −3 S cm −1 for X = Br after annealing at the optimum temperature of 550 °C [94], and 1.8 10 −3 S cm −1 before the annealing, with a relatively good stability toward metallic lithium [95]. The MoS 2 /Li 6 PS 5 X all-solid-state batteries assembled with Li 6 PS 5 Cl-coated MoS 2 as the cathode, Li 6 PS 5 Cl as the solid electrolyte, and an indium-lithium alloy as the anode delivered a stable capacity of 350 mAh g −1 at the current density of 0.13 mA cm −2 .…”

Solid‐State Lithium Batteries: Bipolar Design, Fabrication, and Electrochemistry

“…In addition, these SEs exhibit a large electrochemical window (∼5 V) and high flexibility in chemical compositions by elemental doping. However, the achievable Li + conductivity of argyrodites is strongly dependent on the synthesis process; thus, it is important to develop a scalable, reliable process for highly conductive argyrodite SEs . Unfortunately, most of sulfide‐based SEs suffer from poor chemical stability against moisture, accompanied by significant performance degradation and H 2 S release in ambient environments .…”

“…However, the achievable Li + conductivity of argyrodites is strongly dependent on the synthesis process; thus, it is important to develop a scalable, reliable process for highly conductive argyrodite SEs. [91][92][93][94][95][96] Unfortunately, most of sulfidebased SEs suffer from poor chemical stability against moisture, accompanied by significant performance degradation and H 2 S release in ambient environments. [97,98] More attentions should be paid to enhance the hydrolysis stability of sulfides before the practical use of sulfide-based SEs in SSLBs.…”