Functionalized Sulfide Solid Electrolyte with Air-Stable and Chemical-Resistant Oxysulfide Nanolayer for All-Solid-State Batteries

Abstract

Sulfide solid electrolytes (SEs) with high Li-ion conductivities (σ ion ) and soft mechanical properties have limited applications in wet casting processes for commercial all-solid-state batteries (ASSBs) because of their inherent atmospheric and chemical instabilities. In this study, we fabricated sulfide SEs with a novel core–shell structure via environmental mechanical alloying, while providing sufficient control of the partial pressure of oxygen. This powder possesses notable atmospheric stability and chemical resistance because it is covered with a stable oxysulfide nanolayer that prevents deterioration of the bulk region. The core–shell SEs showed a σ ion of more than 2.50 mS cm –1 after air exposure (for 30 min) and reaction with slurry chemicals (mixing and drying for 31 min), which was approximately 82.8% of the initial σ ion . The ASSB cell fabricated through wet casting provided an initial discharge capacity of 125.6 mAh g –1 . The core–shell SEs thus exhibited improved powder stability and reliability in the presence of chemicals used in various wet casting processes for commercial ASSBs.

Investigating dry room compatibility of sulfide solid-state electrolytes for scalable manufacturing

“…Looking at the P 2p spectra, oxysulfides (PO x S y ) at 133.0 eV form after exposure, and the intensity also increases after the heat treatment in both cases. 11 The P–O signal can be observed at 133.6 eV and 133.8 eV in the air-HT and water-HT samples, indicating the formation of Li 3 PO 4 . 34 The larger PS 4 3− peak area in air-HT than that of water-HT implies a larger degree of LPSCl recovery in air-HT sample.…”

“…For example, Li 2 S–P 2 S 5 can be partially substituted with P 2 O 5 where the inclusion of oxygen significantly enhanced the air stability of the material. 10–12 Another approach is to apply hard and soft acid and base theory by replacing a hard acid, like P, with soft acids, such as Sn and Sb, to form stronger bonds with S, a soft base. 13,14 Several Sn- or Sb-based sulfide electrolytes, such as Li 4 SnS 4 and Li 3 SbS 4 , have been developed and exhibit superior air stability compared to other sulfide-based electrolytes.…”

“…14 Another approach consists of incorporating a thin 50 nm oxygen substitution layer, which was applied to the surface of Li 6 PS 5 Cl (LPSCl) to form a core–shell structure, showing both improved air stability and better preservation of the ionic conductivity. 11…”

Cycle Degradation Analysis by High Precision Coulometry for Sulfide-Based All-Solid-State Battery Cathode under Various Potentials

“…Finally, at potentials higher than 4.55 V, the physical degradation (such as nano/microcrack and subdivision) of NCM active material particles began together with the oxidative decomposition of SE. To circumvent the chemical and physical degradations, it may be effective to develop higher oxidation-tolerant SE materials 30 and cathode active materials, such as single crystal particles, 31 that are less likely to crack.…”

Air‐stable inorganic solid‐state electrolytes for high energy density lithium batteries: Challenges, strategies, and prospects

“…LiFePO 4 (LFP)||Li 7 PS 6 @PVDF‐HFP||Li cells reached an excellent specific capacity of 160 mAh g −1 over 150 cycles. Then, a novel core‐shell structured sulfide solid electrolyte Li 6 PS 5 Cl was proposed through environmental mechanical alloying by Kim et al 106 Benefitting from the oxysulfide nanolayer, the sulfide solid electrolyte exhibited superior stability to air and maintained a high ionic conductivity of 2.50 × 10 −3 S cm −1 . Last but not least, a unique preparation process, ion‐exchange, was utilized to synthesize Li 4 SnS 4 in an aqueous solution 55 .…”