Sulfide Solid Electrolyte Moisture Resistance
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Solution Overview
Problem
Sulfide solid electrolytes containing lithium, phosphorus, and sulfur are prone to generating hydrogen sulfide gas when exposed to moisture, requiring a controlled environment for handling, which limits their practical application.
Innovation Solution
A sulfide solid electrolyte comprising a compound with an argyrodite-type structure and a compound composed of lithium, chlorine, and bromine, with specific peak positions and intensity ratios in X-ray diffraction patterns, is developed to suppress hydrogen sulfide generation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sulfide solid electrolyte containing lithium, phosphorus, and sulfur is used, then high lithium ion conductivity is achieved, but hydrogen sulfide gas is generated when exposed to moisture
Solution Approach 1:
A coating layer comprising lithium halide (LiCl, LiBr, LiI) or a compound containing lithium and halogen is applied to the surface of the sulfide solid electrolyte. This coating layer acts as an intermediary barrier between the sulfide solid electrolyte and moisture in the atmosphere, preventing direct contact and thus suppressing hydrogen sulfide gas generation while allowing lithium ion conductivity to be maintained
Solution Approach 2:
The invention creates a composite structure by combining the sulfide solid electrolyte core material with a protective lithium halide coating layer. This composite material approach allows the inner sulfide solid electrolyte to provide high lithium ion conductivity while the outer coating layer provides moisture resistance and suppresses harmful hydrogen sulfide gas generation
2Object-generated harmful factors
If a sulfide solid electrolyte is handled in a dry room with inert gas, then hydrogen sulfide generation is suppressed, but device complexity and handling difficulty increase
Solution Approach 1:
The protective coating layer of lithium halide is applied in advance to the surface of the sulfide solid electrolyte during the manufacturing process. This preliminary protective action ensures that the electrolyte is inherently resistant to moisture from the outset, eliminating the need for complex dry room environments with inert gas during subsequent handling and battery assembly operations
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
The proposed electrolyte effectively suppresses hydrogen sulfide generation even when exposed to moisture, enhancing moisture resistance and maintaining lithium ion conductivity, thus allowing for safer handling and improved battery performance.
Implementation Method 1
having a peak at each position of 2θ = 29.1° ± 0.5° and 33.7° ± 0.5° in an X-ray diffraction pattern measured by an X-ray diffraction apparatus (XRD) using CuKα1 rays
Data Source
Figure 1~2
Figure 3~4
AI summary
Provided is a novel sulfide solid electrolyte containing Li, P, S, and a halogen, which can be used as a solid electrolyte for a lithium secondary battery or the like, and is able to suppress the generation of a hydrogen sulfide gas even when exposed to moisture in the atmosphere. The sulfide solid electrolyte comprises a crystal phase or a compound having an argyrodite -type structure and containing Li, P, S, and a halogen; and a compound composed of Li, Cl, and Br and having a peak at each position of 2θ = 29.1° ± 0.5° and 33.7° ± 0.5° in an X-ray diffraction pattern.