Fluorinated Polymer Binder for Sulfide Solid Electrolytes
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Solution Overview
Problem
Current solid-state batteries face challenges with sulfide-based composite electrolytes due to poor solvent compatibility, leading to the use of non-conductive binders that reduce ionic conductivity and mechanical properties, limiting their application in high-power devices like electric vehicles and grid energy storage.
Innovation Solution
The use of an amorphous fluorinated polymer as a binder in a classical wet casting method for sulfide-based composite electrolytes, which reduces the negative impact on ionic conductivity and enhances mechanical properties, allowing for the production of high-performance solid electrolyte films suitable for solid-state batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If non-conductive hydrogenated binders are used in sulfide-based composite electrolytes, then mechanical properties are improved, but ionic conductivity is significantly reduced
Solution Approach 1:
The patent changes the chemical composition parameter of the binder from hydrogenated polymers to fluorinated polymers (specifically poly(acrylonitrile-co-1,3-butadiene) with fluorinated side groups). This parameter change allows the binder to maintain mechanical integrity while reducing the formation of isolating layers on sulfide particles, thereby preserving ionic conductivity pathways through the composite electrolyte.
2Reliability
If sulfide solid electrolyte materials are used, then high Li ion conductivity is achieved, but mechanical properties and solvent compatibility deteriorate
Solution Approach 1:
The patent creates a composite electrolyte system combining sulfide solid electrolyte particles (providing high Li ion conductivity) with a fluorinated polymer binder matrix (providing mechanical strength and flexibility). The fluorinated binder specifically complements the sulfide particles by offering good solvent compatibility and mechanical properties while minimizing negative impacts on ionic conductivity, thus achieving a synergistic composite material that balances all required properties.
3Ease of manufacture
If conventional wet casting method is used with non-conductive binders, then ease of manufacture is improved, but ionic conductivity is reduced due to isolating layer formation
Solution Approach 1:
The patent modifies the binder chemical structure parameter by introducing fluorinated groups to the polymer chain. This change prevents the formation of isolating layers on sulfide particle surfaces during the wet casting process, allowing the conventional manufacturing method to proceed while maintaining high ionic conductivity throughout the composite electrolyte structure.
Data Source
AI summary
The present invention relates to a solid electrolyte film comprising sulfide-based solid electrolyte particles dispersed into an amorphous fluorinated binder, said solid electrolyte film being characterized by improved ionic conductivity, improved resistance to oxidation and good mechanical properties. The invention further relates to a process for the manufacture of said solid electrolyte film and to its use in solid state batteries.