Lithium Argyrodite Sulfide Electrolytes with High Ionic Conductivity and Air Stability for All-Solid-State Li-Ion Batteries

Abstract

Solid electrolytes (SEs) are promising candidates for enhancing the energy density and safety of conventional lithium-ion batteries. Recently, lithium thioantimonate iodide argyrodites have been regarded as promising SEs because of their high ionic conductivities and air-stability. In this study, we utilized highenergy ball milling to synthesize Ge-substituted thioantimonate argyrodites and achieved an ionic conductivity of 16.1 mS cm −1 for Li 6.5 Sb 0.5 Ge 0.5 S 5 I, which is the highest value among the reported cold-pressed SE pellets. First-principles calculations reveal that concerted Li-ion migrations through the inter-cage paths substantially improve the ionic conductivity. Li 6.5 Sb 0.5 Ge 0.5 S 5 I shows good compatibility with LiNi 0.5 Co 0.2 Mn 0.3 O 2 -based all-solid-state batteries (ASSBs) after applying Li 3 YCl 6 as a catholyte, which exhibits a high discharge capacity of 164 mAh g −1 and good cycle stability. Ge-substituted thioantimonate argyrodites exhibit excellent air-stability, which facilitates reducing the synthesis and fabrication costs of ASSBs with hygroscopic P-based sulfide SEs. The superionic conductors with high air-stability reported in this study demonstrate substantial promise for the development of ASSBs.

Methylamine Lithium Borohydride as Electrolyte for All‐Solid‐State Batteries

“…an electrolyte stable towards the cathode material, or by coating the cathode material. These approaches are already under investigation for the thiophosphate‐ and argyrodite‐based Li‐electrolytes, which also suffer from relatively low oxidative stabilities [51–56] …”

Air/Water Stability Problems and Solutions for Lithium Batteries

“…are chemically stable to water and air, they are easily oxidized in a pure O 2 environment during cycling [46,47]. Most notably, almost all conventional sulfide SEs are intrinsically unstable and react violently with air/water to release toxic H 2 S gas, which results in their structure being destroyed and Li + conductivity decreasing [15,16,48]. This greatly hinders the practical application of sulfide SEs in ASSBs, making the production, storage, transportation, and battery assembly processes very complicated and heavily dependent on inert atmosphere or drying chamber, which significantly increases the production cost.…”

“…Besides the construction of surface protective layer by liquid-solid reaction mentioned above, gas-solid reaction can also be used to remove surface impurities and construct a suitable protective layer in situ on the surface of Ni-rich cathode materials, which basically avoids the generation of waste water. For example, Kim et al [151] developed a simple and innovative sublimation-induced 16 Energy Material Advances 3.…”

“…Among the three technological routes to realize ASSBs (polymer, oxide, and sulfide), sulfide solid electrolytes (SEs) have emerged as one of the most promising technological routes due to their highest room-temperature ionic conductivity and excellent deformability [7][8][9][10][11][12]. However, sulfide SEs have poor air/water stability and are prone to react with water in ambient air, resulting in changes in their structure and the generation of toxic H 2 S gas, resulting in decreased battery performance and some safety issues [13][14][15][16].…”

Graphene in Solid-State Batteries: An Overview

“…With SSEs, the focus has been on enhancing the room temperature ionic conductivities of the electrolyte to reach or even surpass those achieved for conventional organic liquid electrolytes. There has been success on this front, especially with ceramic electrolytes where room temperature ionic conductivities >10 −2 S cm −1 have been reported [9,[117][118][119]. With good ionic conductivities achieved, the next goal is to integrate Li anodes with SSEs to build batteries delivering the highest possible energy density on a cell level.…”