Fluorinated Binder Composition for Gel-Free Solid-State Battery Slurry
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Solution Overview
Problem
The use of polyvinylidene fluoride as a binder in oxide-based solid-state secondary batteries leads to gelation issues, particularly when interacting with lithium hydroxide, which destabilizes the slurry and hinders homogeneous layer formation, especially in large-area battery production, increasing costs due to high-temperature sintering requirements.
Innovation Solution
A fluorine-containing polymer binder comprising a vinylidene fluoride unit and a fluorinated monomer unit, such as those represented by specific chemical structures, is used to prevent gelation, ensuring stable slurry formation and electrode/electrolyte layer performance without high-temperature sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyvinylidene fluoride is used as a binder in oxide-based solid-state secondary batteries, then the binder provides binding function, but gelation occurs when interacting with lithium hydroxide, destabilizing the slurry and hindering homogeneous layer formation
Solution Approach 1:
The patent changes the chemical structure parameters of the binder by introducing fluorinated monomer units with specific structures (formulae 1 and 2) into the polyvinylidene fluoride chain. This modifies the binder's chemical properties to prevent gelation with lithium hydroxide while maintaining binding functionality, thereby preserving slurry homogeneity and stability.
Solution Approach 2:
The patent creates a composite binder structure by combining polyvinylidene fluoride with specific fluorinated monomer units. This composite approach allows the binder to maintain its binding function while the fluorinated components prevent harmful gelation reactions with lithium hydroxide, resolving the contradiction between binder stability and slurry homogeneity.
2Manufacturing precision
If high-temperature sintering is used to form electrode and electrolyte layers, then layer formation is achieved, but production costs increase and large-area battery production becomes difficult
Solution Approach 1:
The patent changes the processing temperature parameter from high-temperature sintering (400°C or more) to low-temperature processing. The modified binder with fluorinated monomer units enables proper layer formation at lower temperatures, reducing production costs and facilitating large-area battery production while maintaining layer formation quality.
3Productivity
If conventional binders are used to enable large-area battery production, then production scalability improves, but gelation issues persist, increasing costs due to high-temperature sintering requirements
Solution Approach 1:
The patent changes the chemical composition parameters of the binder to include fluorinated monomer units that prevent gelation. This modification enables large-area battery production at lower temperatures, improving productivity while reducing processing costs by eliminating the need for expensive high-temperature sintering equipment and energy consumption.
Data Source
AI summary
An oxide-based solid-state secondary battery and a binder for a solid-state secondary battery using an oxide-based solid electrolyte that contains a fluorine-containing polymer including a vinylidene fluoride unit and a fluorinated monomer unit other than the vinylidene fluoride unit. The fluorinated monomer unit is at least one copolymerization unit (A) selected from a monomer unit having a structure represented by formula (1) and a monomer unit having a structure represented by formula (2):wherein Rf1 and Rf2 are each a linear or branched fluorinated alkyl or fluorinated alkoxy group with 1 to 12 carbon atoms, which optionally contains an oxygen atom between carbon-carbon atoms when the number of carbon atoms is 2 or more.