Binder Composition for Solid Electrolyte Battery Layers
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Solution Overview
Problem
All-solid-state lithium secondary batteries using solid electrolyte batteries exhibit inadequate ion conductivity and poor flexibility in the solid electrolyte and electrode active material layers, leading to issues such as splitting, chipping, or cracking during production, resulting in inadequate battery characteristics.
Innovation Solution
A binder composition for solid electrolyte batteries comprising a particulate polymer copolymer with acrylate and aromatic monomer units, alkyl-modified cellulose, and an organic solvent, which enhances the flexibility and rigidity of the solid electrolyte layers, improving processability and battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders are used in solid electrolyte layers and electrode active material layers, then the layers can be formed and components can be bound, but the layers exhibit poor flexibility leading to splitting, chipping, or cracking during production
Solution Approach 1:
The patent uses a composite binder system comprising both a polymeric binder and a cellulosic binder in specific weight ratios (polymeric binder: 1-50 wt%, cellulosic binder: 50-99 wt%). This composite approach combines the binding strength of polymeric materials with the flexibility and processability of cellulosic materials, preventing splitting, chipping, and cracking while maintaining component adhesion.
2Strength
If conventional binders are used in solid electrolyte layers, then components can be bound together, but ion conductivity within the layer remains insufficient
Solution Approach 1:
The patent optimizes the weight ratio parameters of the binder components, specifically setting the polymeric binder at 1-50 wt% and cellulosic binder at 50-99 wt%. This parameter optimization ensures sufficient ion conductivity while maintaining adequate binding strength, as the cellulosic binder provides ion transport pathways without compromising structural integrity.
3Strength
If the solid electrolyte layer or electrode active material layer is made rigid to ensure structural integrity, then components remain bound, but the layer becomes inflexible and prone to cracking during production
Solution Approach 1:
The patent creates different local properties within the binder system by using two distinct binder types with complementary characteristics. The polymeric binder provides local binding strength and structural integrity, while the cellulosic binder provides local flexibility and processability. This local differentiation allows the layer to maintain structural integrity while remaining flexible during production.
Data Source
AI summary
Provided are a binder composition for a solid electrolyte battery and a slurry composition for a solid electrolyte battery that have excellent processability and can cause a solid electrolyte battery to display excellent battery characteristics. The binder composition contains a particulate polymer of a copolymer including an acrylate monomer unit and an aromatic monomer unit, alkyl-modified cellulose represented by formula (I), and an organic solvent. In formula (I), R1, R2, and R3 each indicate a hydrogen atom or an alkyl group having a carbon number of at least 1 and not more than 4. At least two of R1, R2, and R3 are alkyl groups having a carbon number of at least 2 and not more than 4 in 50 mol % or more of all repeating units. Also, n indicates a natural number.