Solid-State Battery Binder Composition for Output and Cycle Stability
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Solution Overview
Problem
Current binder compositions for all-solid-state secondary batteries face challenges in achieving excellent output characteristics and high-temperature cycle characteristics, particularly due to the complexity of producing specific polymers and the high amounts of antioxidants required, which can affect battery performance.
Innovation Solution
A binder composition comprising a (meth)acrylic polymer with a (meth)acrylic acid ester monomer unit in a specific proportion and an anti-aging agent, such as phenolic or organophosphorus agents, is used to enhance the dispersibility and pressability of the slurry composition, improving the battery's output and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a specific polymer with soft and hard segments is used in the binder to suppress interface resistance, then the interface resistance is reduced, but the production complexity increases due to requiring specific polymer synthesis
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by specifying a polymer containing carboxylic acid groups with particular structural characteristics (soft and hard segments) rather than using complex synthesized polymers. This approach maintains the interface resistance suppression effect while simplifying the production process by using readily available polymer materials with specific functional groups.
Solution Approach 2:
The invention replaces complex, expensive polymer synthesis processes with the use of commercially available polymers containing specific functional groups. This substitution reduces production complexity and cost while maintaining the necessary performance characteristics for suppressing interface resistance in solid electrolyte layers.
2Reliability
If a large amount of antioxidant is added to the binder to prevent oxidation, then oxidative deterioration is prevented, but the output characteristics of the battery are adversely affected
Solution Approach 1:
The invention extracts and eliminates the need for large amounts of antioxidants from the binder composition. By using a polymer with specific chemical structure (containing carboxylic acid groups and appropriate soft/hard segments), the binder inherently resists oxidation without requiring additional antioxidant additives that would harm output characteristics.
Solution Approach 2:
The polymer with carboxylic acid groups acts as an intermediary that provides both adhesion functionality and oxidation resistance. This mediator polymer replaces the dual-function combination of regular binder plus antioxidant, thereby preventing oxidation without the negative effects on output characteristics that large amounts of antioxidants cause.
3Ease of manufacture
If conventional binders are used in the solid electrolyte layer, then the manufacturing process is simple, but the output characteristics and charge/discharge cycle characteristics are insufficient
Solution Approach 1:
The invention applies local quality by specifying particular chemical characteristics for the polymer in the solid electrolyte layer binder (carboxylic acid groups, soft and hard segments) rather than using uniform conventional binders. This localized optimization of binder properties in the solid electrolyte layer improves cycle characteristics while maintaining overall manufacturing simplicity.
Data Source
AI summary
Provided is a binder composition for an all-solid-state secondary battery that can yield an all-solid-state secondary battery having excellent output characteristics and high-temperature cycle characteristics. The binder composition for an all-solid-state secondary battery contains a polymer, an anti-aging agent, and an organic solvent. The polymer includes a (meth)acrylic acid ester monomer unit in a proportion of not less than 25 mass % and not more than 95 mass % and has a gel content of 50 mass % or less. The anti-aging agent is contained in an amount of not less than 0.005 parts by mass and not more than 0.5 parts by mass per 100 parts by mass of the polymer.