Free-Standing Sulfide Electrolyte Sheets With Slurry-Calendered Densification
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Solution Overview
Problem
Existing methods for manufacturing sulfide-based, free-standing sheet-type solid-state electrolytes face challenges such as high pressure requirements, poor mechanical properties, and difficulty in controlling microstructure, leading to limited scalability and inhomogeneous distribution of binder and sulfide particles, which hinder their integration into industrial battery manufacturing processes.
Innovation Solution
A method involving mixing a sulfide ion conductor material with a non-polar or low-polar binder in a solvent, spreading the mixture onto a substrate, calendering to densify, and drying under vacuum to form a flexible, free-standing sheet-type electrolyte with excellent mechanical strength and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sulfide SE membranes are formed by grinding sulfide material into fine powder, mixing with thermoplastic polymer binder, and pressing into sheet, then sheet-type electrolyte can be obtained, but the microstructure control is difficult and binder and sulfide particles are inhomogeneously distributed
Solution Approach 1:
The patent changes the processing parameters by using a slurry-based approach with specific solvent systems and controlled drying conditions instead of direct pressing of dry powders. This allows for better control of microstructure and homogeneous particle distribution while maintaining ease of manufacture
Solution Approach 2:
The patent introduces a slurry medium as an intermediary between the sulfide powder and binder, allowing for better dispersion and distribution of particles before final formation. The slurry acts as a carrier that enables homogeneous mixing and controlled deposition
2Reliability
If pelletizing sulfide SEs is used in laboratory research, then electrolyte samples can be obtained, but the pressures required approach prohibitive levels when scaled up
Solution Approach 1:
The patent replaces the high-pressure mechanical pelletizing system with a low-pressure slurry casting system. Instead of using extreme pressures to form dense pellets, the method uses a liquid slurry that can be deposited and dried at much lower pressures, maintaining electrolyte quality while enabling scale-up
Solution Approach 2:
The patent utilizes phase transitions by working with the binder in a softened or molten state during slurry preparation, then allowing it to solidify during drying. This phase change enables formation at low pressure that would be impossible with cold-pressing alone
3Ease of manufacture
If sulfide SE pellets are used, then electrolyte can be formed, but their poor mechanical properties result in finite lower bound on thickness which limits cell-based energy densities
Solution Approach 1:
The patent creates a composite material system where sulfide particles are embedded in a polymer binder matrix. This composite structure combines the high ionic conductivity of sulfides with the mechanical flexibility of polymers, enabling thin-film formation with adequate mechanical strength
Solution Approach 2:
The patent produces flexible thin-film electrolytes by using the slurry casting method followed by controlled drying. The resulting free-standing films can be made much thinner than pressed pellets while maintaining mechanical integrity, enabling higher energy densities
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 method enables the production of thin, flexible, and mechanically robust sulfide-based solid-state electrolytes suitable for battery cells, with improved ionic conductivity and compatibility with industrial roll-to-roll processes.
Implementation Method 1
mixing a sulfide ion conductor-containing material and a binder in a solvent to obtain a slurry composition
Implementation Method 2
disposing the slurry composition onto a planar substrate. The method further includes spreading the slurry composition on the substrate
Implementation Method 3
calendering the film to densify the film
Implementation Method 4
drying the film under vacuum
Data Source
AI summary
A method of manufacturing a free-standing, sheet-type solid-state electrolyte is provided. The method includes: mixing a sulfide ion conductor-containing material and a non-polar or low-polar binder in a solvent to obtain a slurry composition; disposing the slurry composition onto a planar substrate; spreading the slurry composition on the substrate to obtain a film; calendering the film to densify the film; and subsequently drying the film under vacuum. The binder may be polyisobutylene and may be present in the slurry composition in an amount of up to 10 wt. %, optionally between 1 and 5 wt. %. The sulfide ion conductor-containing material may be a lithium argyrodite having the chemical formula Li6PS5X in which X is Cl, Br, or I. The solvent may be toluene or xylene. The film may have a thickness of between 10 and 200 μm.