Protective Compound Layers for Moisture-Sensitive Sulfide Glass Electrolytes
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Solution Overview
Problem
Sulfide glass solid electrolytes are highly sensitive to moisture, leading to hydrolysis and reactions with lithium metal, which affects the performance and stability of lithium metal batteries, particularly during storage, transportation, and assembly processes.
Innovation Solution
A thin metal layer is coated onto sulfide glass surfaces, which is then converted into a protective compound layer, such as a metal oxide, sulfide, nitride, or halogenide, to prevent moisture reaction and allow lithium ion transport, thereby enhancing the stability and performance of lithium metal batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If sulfide glass solid electrolyte is used to achieve high energy density in lithium metal batteries, then battery performance is improved, but the electrolyte becomes highly sensitive to moisture causing hydrolysis and reactions with lithium metal
Solution Approach 1:
A thin protective metal layer (such as aluminum, titanium, or tungsten) is deposited onto the sulfide glass solid electrolyte surface to act as an intermediary barrier. This layer prevents direct contact between the moisture-sensitive sulfide glass and environmental moisture, while still allowing lithium ion transport through the protective layer, thus resolving the contradiction between maintaining high energy density and reducing moisture sensitivity
Solution Approach 2:
The solution creates a composite structure combining the sulfide glass solid electrolyte with a protective metal layer. This composite material system maintains the high ionic conductivity and energy density benefits of the sulfide glass while adding the moisture resistance properties of the metal protective layer, effectively addressing both requirements simultaneously
2Stability of the object's composition
If strict dryness requirements are imposed on cell components to prevent moisture reactions, then electrolyte stability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The protective metal layer is applied in advance to the sulfide glass solid electrolyte surface before cell assembly. This preliminary protective action ensures that the electrolyte is already shielded from moisture, allowing for more relaxed dryness requirements during subsequent manufacturing and assembly processes, thus reducing manufacturing complexity while maintaining electrolyte stability
3Object-affected harmful factors
If thin metal layer is coated onto glass surfaces to provide protection, then moisture resistance is improved, but the metal layer must be removed prior to cell assembly adding process steps
Solution Approach 1:
The protective metal layer undergoes a controlled conversion process where it transforms from a pure metal state to a compound state (such as oxide, sulfide, nitride, or halogenide) through exposure to specific atmospheric conditions or chemical treatments. This parameter change in the metal layer's chemical state enables it to maintain moisture resistance while becoming electrochemically functional and eliminating the need for removal before cell assembly
4Device complexity
If protective compound layer is converted in place rather than removed, then process complexity is reduced, but the layer must maintain both protection and electrochemical functionality
Solution Approach 1:
The converted protective compound layer is designed to perform multiple functions simultaneously: it maintains the moisture barrier function of the original protective layer while also providing electrochemical functionality for lithium ion transport. This multi-functionality allows the layer to serve both protective and active electrochemical roles, satisfying both requirements without adding process complexity
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 protective compound layer significantly reduces the risk of moisture-induced reactions, enabling higher moisture content in electrolytes, improving the dryness requirements for cell components and maintaining the integrity of sulfide glass solid electrolytes, especially during assembly and storage.
Implementation Method 1
a thin metal layer may be coated onto the glass surfaces to provide such protection, and removed prior to cell assembly (e.g., by ion etching the metal layer to remove it). In other embodiments a thin metal layer coating may be converted to a thin electrochemically functional and protective compound layer rather than removed prior to cell assembly. In accordance with the present disclosure, the converted protective compound layer may be composed of the metal element of the thin protective metal layer and a non-metal selected from the group consisting of a nonmetal chalcogen, nonmetal halogen, and nonmetal pnictogen.
Implementation Method 2
The converted protective compound layer is electrochemically functional in that it allows for through transport of lithium ions.
Implementation Method 3
Sulfide glasses are known to be highly sensitive to moisture. Protection of sulfide glass solid electrolyte surfaces against reaction with moisture during sulfide glass solid electrolyte storage, transportation, and cell assembly in a dry room atmosphere can provide important benefits.
Data Source
AI summary
A sulfide glass solid electrolyte sheet can be protected from reaction with moisture by a thin metal layer coating converted to a thin electrochemically functional and protective compound layer. The converted protective compound layer is electrochemically functional in that it allows for through transport of lithium ions.