Sulfide Solid Electrolyte Ionic Conductivity — PatSnap Eureka
Improving Ionic Conductivity of Sulfide-Based Solid Electrolytes at Room Temperature
Sulfide solid electrolytes now reach 10⁻⁴ to 10⁻² S cm⁻¹ at room temperature—the most competitive inorganic class for all-solid-state battery commercialization. Explore the patent-backed strategies driving this breakthrough.
Doping Strategies That Maximize Room-Temperature Ionic Conductivity
The primary lever for maximizing room-temperature ionic conductivity in sulfide SSEs is compositional tuning of the host lattice. Four industrially validated doping routes are documented across 60+ patent and literature sources.
Li₇₋ₓPS₆₋ₓHaₓ — Halogen Substitution (x = 0.2–1.8)
Mitsui Mining & Smelting's 2019 patent discloses a cubic crystal structure (space group F-43m) with halogen (Cl or Br) substitution at x values between 0.2 and 1.8. This achieves high ionic conductivity while controlling electron conductivity through careful stoichiometry. Halogen doping is the most industrially validated approach in the argyrodite family, forming the foundation of Mitsui's coherent IP portfolio on sulfide SSE composition and structure.
Space group F-43m · Ha = Cl or Br · x: 0.2–1.8100–1000 ppm Al in Argyrodite → ≥4.0 mS/cm
Mitsui Mining & Smelting's 2024 patent incorporates aluminum at 100–1000 ppm by mass into an argyrodite-type sulfide framework, achieving lithium-ion conductivity of 4.0 mS/cm or greater at room temperature. The aluminum additive increases contact points and contact areas between solid electrolyte particles, directly enhancing the bulk ionic conduction pathway — a scalable approach compatible with existing argyrodite manufacturing.
Al: 100–1000 ppm · ≥4.0 mS/cm confirmedN + Multi-Element M Dopants — Dual Conductivity & Safety Gain
GS Yuasa International's 2025 European patents disclose crystalline sulfide electrolytes incorporating nitrogen together with elements M (Al, Si, B, Mg, Zr, Ti, Hf, Ca, Sr, Sc, Ce, Ta, Nb, W, Mo, or V). Ionic conductivity graphs at 25°C confirm nitrogen-doped structures outperform non-doped comparatives, while simultaneously reducing hydrogen sulfide generation under ambient humidity. This dual performance-safety optimization is a significant differentiator for manufacturing-safe deployment.
N + M dopants · improved 25°C conductivity · reduced H₂SMulti-Element Argyrodite Variants from JX Advanced Metals
JX Nippon Mining & Metals Corporation (2025) discloses Li₈GeS₅₋ₓTe₁₊ₓ (−0.5 ≤ x < 0 or 0 < x ≤ 0.375), where partial replacement of sulfur with tellurium modifies local lattice polarizability and ion channel dimensions. JX Advanced Metals Corporation (2026) further discloses Li₄P₁₋ₓSiₓS₄₋ₓHaₓI (Ha = Cl, Br, or I; 0.05 < x ≤ 0.3), combining silicon substitution onto the phosphorus site with halogen doping for further ion conductivity improvement.
Li₈GeS₅₋ₓTe₁₊ₓ · Li₄P₁₋ₓSiₓS₄₋ₓHaₓI · 2025–2026Quantifying the Sulfide SSE Innovation Landscape
Patent and literature data from PatSnap Eureka reveals the distribution of technical approaches and the conductivity gains achievable through each strategy.
Innovation Strategy Distribution Across 60+ Sources
Compositional engineering and doping accounts for the largest share of patent activity in sulfide SSE conductivity improvement, followed by crystal phase and glass-ceramic control.
Room-Temperature Ionic Conductivity by Strategy (mS/cm)
Al-doped argyrodite achieves ≥4.0 mS/cm, more than 3× the Li₆PS₅Cl benchmark of 1.3 mS/cm. The sulfide SSE class overall spans 0.1–10 mS/cm.
Glass-Ceramic Design and Scalable Liquid-Phase Processing
Beyond composition, controlling the crystalline or glassy phase of the sulfide material is fundamental to room-temperature conductivity. Toyota Motor Corporation has extensively patented glass-based sulfide electrolytes, demonstrating that an ion conductor with ortho-composition doped with LiI—processed as glass with a glass transition point via mechanical milling—yields high Li-ion conductivity without oxidative decomposition of the LiI additive. The glassy phase enables room-temperature pressure sintering and good interfacial contact, key for ASSB integration.
The Li₇P₃S₁₁ crystalline phase is recognized as among the highest conductivity phases in lithium sulfide electrolytes. A 2017 study demonstrated that Li₇P₃S₁₁ with small particle size and favorable mechanical properties, produced via a liquid-phase process, achieves high ionic conductivity meeting all-solid-state battery requirements for energy and power density. GS Yuasa's 2025 patents further exploit Li₇P₃S₁₁, Li₄P₂S₆, and β-Li₃PS₄ crystal phases as part of its nitrogen-multi-element doped framework, with specific XRD diffraction peak assignments confirming phase purity.
Computational approaches have directly informed conductivity improvement strategies. As calculated via the DV-Xα cluster method, the relationship between ionic conductivity and the differential total bond overlap population (DBOP) of the moving cation provides a quantitative predictor for ion mobility in sulfide-based alkali-ion conductors. Low bond energies and high covalent character—characteristic of sulfide over oxide frameworks—are key to achieving high room-temperature conductivity. This insight is validated by WIPO patent filings spanning multiple jurisdictions.
Liquid-phase synthesis has emerged as a viable industrial alternative to solid-state mechanical milling. Researchers at Toyohashi University of Technology provide solvent selection guidelines based on donor number and dielectric constant to optimize reaction kinetics while maintaining the moisture sensitivity constraints inherent to sulfide systems. Particle morphology also matters: ENFLOW Co., Ltd.'s 2025 patent specifies that sulfide SSE particles with a circularity parameter C ≥ 0.8 (defined by 4πA/P²) achieve superior packing density and ion conduction performance. For deeper context on scalable battery materials manufacturing, see the U.S. Department of Energy's solid-state battery roadmap.
Electrode-Electrolyte Interface Engineering for Practical ASSBs
High bulk ionic conductivity is necessary but not sufficient. The electrolyte-electrode interface must also conduct ions efficiently — and the strategies below, documented in patents from Toyota and LG Energy Solution, are essential for room-temperature ASSB performance.
Reaction-Suppressing Coatings on Cathode Particles
Toyota Motor Corporation's 2023 patent discloses positive electrode active material particles coated with a reaction-suppressing layer as an aggregate to prevent delamination during cycling. This minimizes the formation of poorly conductive interphases, maintaining lithium-ion transport pathways across the cathode-electrolyte boundary. The PatSnap life sciences and materials platform tracks this entire coating IP cluster.
Metal Sulfide Shell on Lithium Metal Oxide Core
LG Energy Solution's 2024 patent takes a parallel approach: a shell of metal sulfide particles of specific size range adsorbed on a lithium metal oxide core reduces cracking and reactivity at the electrode-electrolyte interface, directly improving lithium-ion mobility and charge-discharge capacity. This core-shell architecture is an industrially scalable solution to interface degradation in sulfide-based ASSBs.
Composite Sulfide-Polymer Bi-Percolating Ion Channels
Researchers at Ulsan National Institute of Science and Technology (2023) demonstrated that argyrodite Li₆PS₅Cl combined with a gel polymer electrolyte containing Li⁺-glyme complex forms bi-percolating ion channels. Ion conduction across the LPSCl-GPE interface is facilitated by controlling solvation/desolvation of the Li⁺-glyme complex, enabling a scalable composite electrolyte sheet measuring 8 × 6 cm².
Sulfide-Polymer Binder via PS₄³⁻ + Iodine Reaction
Researchers at the Osaka Research Institute of Industrial Science and Technology (2021) developed a sulfide polymer electrolyte by reacting PS₄³⁻ anions with iodine to form disulfide-linked chains, creating a sticky gel that acts as a lithium-ion-conductive binder. This eliminates mechanical contact loss at electrode-electrolyte interfaces during cycling, preserving effective ionic conductivity under repeated volume change.
Key Institutional Contributors to Sulfide SSE Conductivity IP
Patent analysis across the dataset identifies the most prolific institutional contributors and their distinct technical focus areas.
| Institution | Primary Technical Focus | Key Patent / Study | Year |
|---|---|---|---|
| GS Yuasa International Ltd. | Nitrogen + multi-element doped crystalline SSEs; Li₇P₃S₁₁, Li₄P₂S₆, β-Li₃PS₄ phases; reduced H₂S generation | EP e816b78b, EP 52141840 | 2025 |
| Mitsui Mining & Smelting Co., Ltd. | Argyrodite-type Li₆PS₅Cl family; halide doping; Al incorporation (100–1000 ppm); core-shell moisture barrier | Argyrodite halide patent; Al-doped SSE patent | 2019–2024 |
| Toyota Motor Corporation | Glass-ceramic LiI-doped ortho-composition SSEs; anode pre-lithiation; cathode reaction-suppressing coatings | EP 132ef881, EP 0b549b43, EP 8f34ee39 | 2018–2023 |
| LG Energy Solution / LG Chem | Ionic conductivity restoration; phosphorus-free SSE formulation; cathode active material engineering | EP 1f5a2bdc, IN 96527f4c | 2019–2024 |
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Seven Validated Strategies to Improve Sulfide SSE Ionic Conductivity
Each strategy below is directly traceable to a specific patent or peer-reviewed study in the dataset. For deeper exploration, PatSnap customers use Eureka to map these IP clusters and identify white spaces.
- Halogen doping of argyrodite-type frameworks (Li₇₋ₓPS₆₋ₓHaₓ, Ha = Cl or Br) at x = 0.2–1.8 is the primary industrially validated approach to high room-temperature ionic conductivity (Mitsui Mining & Smelting, 2019).
- Nitrogen and multi-element co-doping into crystalline sulfide frameworks simultaneously improves room-temperature ionic conductivity at 25°C and reduces H₂S gas generation (GS Yuasa EP 52141840, 2025).
- Glass-ceramic design with LiI doping of ortho-composition sulfide conductors enables room-temperature pressure sintering and high Li-ion conductivity without oxidative LiI decomposition (Toyota, 2018).
- Aluminum incorporation at 100–1000 ppm into argyrodite-type SSEs increases inter-particle contact area and delivers ionic conductivity ≥4.0 mS/cm (Mitsui Mining & Smelting, 2024).
- Ionic conductivity recovery via low-dielectric-constant solvent treatment (dielectric constant <7) addresses conductivity loss during storage and processing (LG Energy Solution, 2024).
- Composite sulfide-polymer electrolytes using Li₆PS₅Cl and gel polymer electrolyte form bi-percolating ion channels, enabling scalable 8 × 6 cm² thin-film production (UNIST, 2023).
- Cathode-side interface engineering — including reaction-suppressing coatings and metal sulfide shells on active material particles — preserves effective ionic transport at the electrode-electrolyte boundary (Toyota 2023; LG Energy Solution 2024).
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Sulfide SSE Ionic Conductivity — Key Questions Answered
Sulfide SSEs currently achieve room-temperature ionic conductivities in the range of 10⁻⁴ to 10⁻² S cm⁻¹, as noted by multiple review studies, making them the most competitive inorganic electrolyte class for near-term ASSB commercialization.
Halogen doping of argyrodite-type frameworks (Li₇₋ₓPS₆₋ₓHaₓ, Ha = Cl or Br) at specific x values between 0.2 and 1.8 is a primary, industrially validated approach to achieving high room-temperature ionic conductivity, as documented by Mitsui Mining & Smelting's argyrodite halide patent (2019). The cubic crystal structure belonging to space group F-43m achieves high ionic conductivity while controlling electron conductivity through careful stoichiometry.
Aluminum incorporation at 100–1000 ppm into argyrodite-type sulfide SSEs increases inter-particle contact area and delivers ionic conductivity of 4.0 mS/cm or greater at room temperature, as disclosed in Mitsui Mining & Smelting's aluminum-doped SSE patent (2024). The aluminum additive increases contact points and contact areas between solid electrolyte particles, directly enhancing the bulk ionic conduction pathway.
Ionic conductivity recovery via low-dielectric-constant solvent treatment addresses the practical problem of conductivity loss during storage and processing of sulfide SSEs. LG Energy Solution's patented method (2024) discloses contacting a degraded sulfide SSE with a solvent of dielectric constant less than 7, then drying, fully restoring ionic conductivity.
Nitrogen and multi-element co-doping into crystalline sulfide frameworks simultaneously improves room-temperature ionic conductivity at 25°C and reduces H₂S gas generation, as shown in GS Yuasa's EP patent 52141840 (2025). The nitrogen-doped structures outperform comparative non-doped examples in ionic conductivity graphs at 25°C.
Composite sulfide-polymer electrolytes using Li₆PS₅Cl and gel polymer electrolyte form bi-percolating ion channels, enabling scalable thin-film production with maintained room-temperature conductivity, as elucidated by UNIST researchers (2023). Ion conduction across the LPSCl-GPE interface is facilitated by controlling solvation/desolvation of the Li⁺-glyme complex, enabling a scalable composite electrolyte sheet of 8 × 6 cm².
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References
- Sulfide-based solid electrolyte for lithium ion battery — Mitsui Mining and Smelting Co., Ltd., 2019
- Solid electrolyte, electrode mix, solid electrolyte layer, and all-solid-state battery — Mitsui Mining & Smelting Co., Ltd., 2024
- Sulfide-based solid electrolyte and all-solid-state lithium ion battery (Li₈GeS₅₋ₓTe₁₊ₓ) — JX Nippon Mining & Metals Corporation, 2025
- Sulfide-based solid electrolyte and all-solid-state lithium ion battery (Li₄P₁₋ₓSiₓS₄₋ₓHaₓI) — JX Advanced Metals Corporation, 2026
- Sulfide solid electrolyte and all-solid-state battery (EP e816b78b) — GS Yuasa International Ltd., 2025
- Sulfide solid electrolyte and all-solid-state battery (EP 52141840) — GS Yuasa International Ltd., 2025
- Sulfide solid electrolyte and all-solid-state battery (EP 206c96a8) — GS Yuasa International Ltd., 2025
- Sulfide solid electrolyte material and lithium solid state battery (EP 132ef881) — Toyota Jidosha Kabushiki Kaisha, 2018
- Sulfide solid electrolyte material and lithium solid state battery (EP 0b549b43) — Toyota Jidosha Kabushiki Kaisha, 2018
- Method for restoring ion conductivity of sulfide-based solid electrolyte (EP 1f5a2bdc) — LG Energy Solution, Ltd., 2024
- Method for restoring ion conductivity of sulfide-based solid electrolyte (IN 96527f4c) — LG Energy Solution, Ltd., 2024
- All-solid-state battery with a sulfide-based solid electrolyte — LG Chem, Ltd., 2019
- Positive electrode active material for sulfide-based all-solid-state battery — LG Energy Solution, Ltd., 2024
- Use of a positive electrode material for a sulfide-based solid electrolyte battery — Toyota Jidosha Kabushiki Kaisha, 2023
- Sulfide-based solid electrolyte for lithium secondary battery (core-shell) — Mitsui Mining and Smelting Co., Ltd., 2021
- Sulfide solid electrolyte and battery (argyrodite + LiClBr) — Mitsui Mining & Smelting Co., Ltd., 2022
- Sulfide solid electrolyte, all solid state battery, and method for producing sulfide solid electrolyte — Tokyo Institute of Technology, 2024
- Sulfide-based solid electrolyte and all-solid-state battery including the same (ENFLOW, circularity C ≥ 0.8) — ENFLOW Co., Ltd., 2025
- High-Performance All-Solid-State Lithium–Sulfur Batteries Enabled by Slurry-Coated Li₆PS₅Cl/S/C Composite Electrodes — Zhejiang University of Technology, 2021
- Liquid-phase synthesis review — solvent selection for sulfide SSEs — Toyohashi University of Technology, 2023
- Li₃PS₄ liquid-phase synthesis parameter optimization — Toyohashi University of Technology, 2020
- DV-Xα DBOP computational analysis of sulfide alkali-ion conductors — Hyogo University of Teacher Education, 2020
- Li₇P₃S₁₁ liquid-phase synthesis — high conductivity and mechanical properties — Faculty of Engineering study, 2017
- Sulfide SSE interface instability review — Lawrence Berkeley National Laboratory, 2021
- Argyrodite Li₆PS₅Cl + gel polymer electrolyte composite — bi-percolating ion channels — Ulsan National Institute of Science and Technology (UNIST), 2023
- PS₄³⁻ + iodine sulfide-polymer binder for ASSB interfaces — Osaka Research Institute of Industrial Science and Technology, 2021
- WIPO — World Intellectual Property Organization (patent filings reference)
- U.S. Department of Energy — Solid-State Battery Roadmap
- European Patent Office (EPO) — Battery Technology Patent Landscape
All data and statistics on this page are sourced from the references above and from PatSnap's proprietary innovation intelligence platform.
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