Solid-State Battery Cathode Layer With Fibrillated PTFE Binder
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing cathode units in solid state batteries face challenges in achieving large-area production with low electrical and ionic resistances due to high binder content and solvent-based processes, which lead to solvation issues and increased resistance.
Innovation Solution
A cathode unit using a composite material with less than 1% polytetrafluoroethylene (PTFE) as a binding agent, partially fibrillated, and a solvent-free powder mixture, applied to an electrically conductive current collector, allowing for a flexible and compactable layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based processes are used for layer application, then the materials can be applied, but solvation of the layer below occurs and electrical and ionic resistances increase
Solution Approach 1:
The invention extracts and eliminates the solvent component from the layer application process. By using a solvent-free powder mixture that is compacted directly into a flexible composite layer, the patent avoids the harmful solvation effects and resistance increases that occur with solvent-based processes, while still enabling effective material application.
Solution Approach 2:
The invention changes the physical state and processing parameters of the binding agent. By using fibrillated PTFE with specific fiber morphology and compacting the powder mixture under controlled pressure and temperature conditions, the process transitions from wet chemical application to a dry compaction process, eliminating solvent-related problems while maintaining layer formation capability.
2Strength
If high binder content is used to ensure sufficient binding, then the layer can be formed, but electrical and ionic resistances increase
Solution Approach 1:
The invention changes the physical form of the binding agent from conventional granular or powder binders to fibrillated PTFE with specific fiber morphology. This parameter change in the binding agent's physical state enables effective binding at much lower concentrations (0.1-1 wt%) compared to conventional binders, thereby reducing electrical and ionic resistances while maintaining sufficient mechanical strength.
Solution Approach 2:
The invention uses a composite material system combining electrode material, solid electrolyte, conductive additive, and fibrillated PTFE binder. This composite approach leverages the unique properties of fibrillated PTFE fibers to provide binding functionality with minimal binder content, resolving the contradiction between binding strength and electrical/ionic conductivity.
3Ease of manufacture
If conventional binders are used in wet chemical processes, then layers can be applied, but the binder content must be several weight percent or higher
Solution Approach 1:
The invention extracts and eliminates the solvent component from the layer application process. By using a solvent-free powder mixture that is compacted directly into a flexible composite layer, the patent avoids the harmful solvation effects and resistance increases that occur with solvent-based processes, while still enabling effective material application.
Solution Approach 2:
The invention changes the physical state and processing parameters of the binding agent. By using fibrillated PTFE with specific fiber morphology and compacting the powder mixture under controlled pressure and temperature conditions, the process transitions from wet chemical application to a dry compaction process, eliminating solvent-related problems while maintaining layer formation capability.
4Reliability
If oxide solid electrolytes are processed at high sintering temperatures, then chemical and mechanical stability is achieved, but processing into thin electrodes or membranes becomes difficult
Solution Approach 1:
The invention changes the processing temperature parameter from high sintering temperatures to lower compression and heating temperatures. By using fibrillated PTFE as a binder and applying pressure and heat below conventional sintering temperatures, the patent enables processing of thin electrodes and membranes while maintaining chemical and mechanical stability through the composite material structure.
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 solution enables low electrical and ionic resistances, improved processing, and simplified application, resulting in a free-standing film with enhanced mechanical properties and reduced binder content.
Implementation Method 1
the polytetrafluoroethylene is at least partially present as a fibrillated polytetrafluoroethylene
Implementation Method 2
The flexible composite layer is subsequently compacted
Implementation Method 3
the polytetrafluoroethylene in the composite material is present as an at least partially monoaxially and/or biaxially oriented polytetrafluoroethylene to set the mechanical properties as desired
Data Source
AI summary
A cathode unit for a solid-state battery and a method for producing the cathode unit. The cathode unit has a layer made of a composite material (2) which has an electrode material, a solid electrolyte material, an electrically conductive conducting additive and polyetrafluoroethylene as a binder. The composite material contains less than 1 wt. % polyetrafluoroethylene and the polyetrafluoroethylene is present, at least in part, as fibrillated polyetrafluoroethylene.