Argyrodite Sulfide Solid Electrolyte for High Li-Ion Conductivity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing sulfide solid electrolytes in lithium-ion secondary batteries face limitations in lithium ion conductivity due to the risk of corrosion from halogen elements like chlorine, which also restricts the increase in conductivity, and there is a need for higher conductivity to enhance battery performance.

Innovation Solution

The arrangement of lithium ions in an argyrodite crystal is optimized by adjusting the composition and manufacturing conditions to set the maximum distance between Li ions to 2.54 Å or shorter, using a composition formula Lia-M-Zb-Hac, where M is divalent to pentavalent cations, Z is divalent anions, and Ha is F, Cl, or Br, with specific ratios and inclusion of elements like P, Si, and O to enhance conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the content of halogen element Ha (particularly chlorine) is increased to improve lithium ion conductivity, then lithium ion conductivity increases, but corrosion risk to aluminum current collector foil increases

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidcorrosion risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by replacing chlorine with bromine or iodine in the argyrodite crystal structure. This substitution maintains the desired lithium ion conductivity while eliminating the corrosive effects of chlorine on aluminum current collectors. The specific composition formula Li7-xPS6-xHax where Ha is Br or I instead of Cl achieves this parameter optimization.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses alternative halogen elements (bromine, iodine) that serve the same functional role as chlorine in enhancing lithium ion conductivity but without the harmful side effects. These alternative elements act as substitutes that achieve the desired electrical properties without compromising structural integrity or causing corrosion.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If liquid electrolytes are used to achieve good ion conductivity, then ion conductivity is maintained, but safety issues such as liquid leakage and bursting into flames occur

Engineering Contradiction:
Improveion conductivityVSAvoidsafety hazards
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent transitions from liquid electrolyte phase to solid electrolyte phase by using argyrodite crystals. This phase change eliminates the safety hazards associated with liquid electrolytes (leakage, combustion) while maintaining high ion conductivity through the solid crystal structure. The sulfide-based solid electrolyte achieves liquid-like conductivity without liquid-like safety risks.

Inventive Principle:
Principle #36Phase transitions

3Reliability

If a large case is used to ensure safety with liquid electrolytes, then safety is improved, but battery miniaturization is prevented

Engineering Contradiction:
ImprovesafetyVSAvoidcase size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

By transitioning to solid electrolyte phase, the patent eliminates the need for large safety margins and protective casings required for liquid electrolytes. The solid argyrodite crystal structure inherently provides safety without requiring additional volume for containment or protection, enabling battery miniaturization.

Inventive Principle:
Principle #36Phase transitions

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly increases lithium ion conductivity, improving battery performance and cycle characteristics while maintaining a stable crystal structure, enabling higher efficiency and safety in lithium-ion secondary batteries.

Implementation Method 1

sulfide ions are higher in polarizability and exhibit higher ion conductivity than oxide ions

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS12586815B2Sulfide-based solid electrolyte used for lithium ion secondary battery and production method for same, solid electrolyte layer, and lithium ion secondary battery
Publication Date: 2026.03.24 AGC INC

AI summary

A sulfide solid electrolyte to be used in a lithium-ion secondary battery, including an argyrodite crystal, in which the crystal is represented by a composition formula Lia-M-Zb-Hac; M is at least one element selected from Na, K, and elements each of which exists as any of divalent to pentavalent cations in the crystal; Z is at least one element selected from elements that exists as a divalent anion in the crystal; Z includes S; Ha is at least one element selected from the group consisting of F, Cl, Br, and I; a, b, and c in the composition formula indicate a ratio among contents (unit: at %) of the respective elements and satisfy 5<a<7, 4<b<6, and 0<c<2; and a maximum distance between Li ions in the crystal is 2.54 Å or shorter.