Core-Shell Solid Electrolyte for Conductivity and Moisture Stability
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Solution Overview
Problem
Sulfide-based solid electrolytes for all-solid-state batteries face challenges such as low lithium ion conductivity, instability in the crystalline phase, poor atmospheric stability, and difficulty in mass production due to hydrogen sulfide generation when exposed to moisture, hindering commercialization.
Innovation Solution
A solid electrolyte with a core-shell structure is developed, where the cores are made of a first electrolyte (e.g., Li6PS5I) and the shells of a second electrolyte (e.g., Li6PS5Br or Li6PS5Cl) are applied, with specific particle size and density ratios, and optionally a skin layer, to enhance lithium ion conductivity and atmospheric stability, and the manufacturing method involves preparing and mixing these electrolytes with shear stress application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide-based solid electrolyte is used to achieve high lithium ion conductivity, then lithium ion conductivity is improved, but atmospheric stability deteriorates due to hydrogen sulfide generation when exposed to moisture
Solution Approach 1:
The solid electrolyte is divided into core and shell parts with different compositions. The core contains sulfide-based electrolyte for high lithium ion conductivity, while the shell contains oxide-based electrolyte for atmospheric stability. This segmentation allows each part to perform its specialized function without compromising the other.
Solution Approach 2:
The invention uses a composite structure combining sulfide-based solid electrolyte (core) and oxide-based solid electrolyte (shell). The sulfide phase provides high ionic conductivity while the oxide phase provides chemical stability and protects against moisture, creating a material that exhibits both high conductivity and atmospheric stability simultaneously.
2Quantity of substance
If sulfide-based solid electrolyte is used to achieve high energy density, then energy density is improved, but manufacturing difficulty increases due to vulnerability to atmospheric exposure
Solution Approach 1:
The oxide-based shell is formed beforehand to protect the sulfide-based core from atmospheric exposure during manufacturing and storage. This protective layer prevents degradation and hydrogen sulfide generation, making the high-energy-density sulfide electrolyte manufacturable and stable under normal conditions.
Solution Approach 2:
The oxide-based shell creates an inert protective environment around the sulfide-based electrolyte, shielding it from moisture and oxygen in the atmosphere. This allows the sulfide electrolyte to maintain its high performance without requiring complex atmospheric control during handling and manufacturing.
3Stability of the object's composition
If sulfide-based solid electrolyte is used to achieve stable crystalline phase, then structural stability is improved, but atmospheric stability deteriorates due to hydrogen sulfide generation
Solution Approach 1:
The harmful function of hydrogen sulfide generation is extracted and isolated to the core region, while the shell region is designed to prevent this harmful effect from manifesting. The oxide-based shell acts as a barrier that contains the sulfide phase and prevents it from reacting with atmospheric moisture, thereby eliminating hydrogen sulfide generation while preserving crystalline stability.
Solution Approach 2:
The potential harm of the sulfide-based electrolyte (hydrogen sulfide generation) is converted into a benefit by using it as the core material for high conductivity, while the oxide shell transforms the stability issue into a protective feature. The shell's chemical stability becomes the protective mechanism that prevents harm, turning what was a liability into an asset.
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
Disclosed are a solid electrolyte and method of manufacturing the same. The solid electrolyte may include a core including a first electrolyte represented by Chemical Formula 1, and a shell including a second electrolyte represented by Chemical Formula 2, and disposed on a surface of the core. [Chemical Formula 1] LiaPSbX1c Here, a satisfies an equation 4≤a≤7, b satisfies an equation 3≤b≤7, c satisfies an equation 0≤c≤2, and X1 includes Br or I. [Chemical Formula 2] LidPSeX2f Here, d satisfies an equation 4≤d≤7, e satisfies an equation 3≤e≤7, f satisfies an equation 0≤f≤2, X2 includes Cl or Br, and an ionic radius of X1 is greater than an ionic radius of X2.