Nitrile Binder Composition for Non-Aqueous Battery Electrodes
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Solution Overview
Problem
Existing binder compositions for non-aqueous electrolyte batteries have low molecular weights, leading to instability and difficulty in improving the cycle property of batteries, as increasing molecular weight is challenging due to issues with polymerization methods and stability of the binder solution and electrode slurry.
Innovation Solution
A binder composition with a polymer A having a weight-average molecular weight of 500,000 to 2,000,000 and a narrow molecular weight distribution, derived from a nitrile group-containing monomer and an ethylenically unsaturated compound, is used, along with a polymer B containing acrylonitrile or methacrylonitrile, to enhance stability and cycle property.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the molecular weight of the polymer in the binder composition is increased to improve cycle property, then the strength of the binder composition is improved, but the stability of the binder solution and electrode slurry deteriorates due to gelation and precipitation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight of the polymer within the range of 100,000 to 1,000,000 and limiting the molecular weight distribution (Mw/Mn) to 20 or less. This optimization resolves the contradiction by finding the optimal molecular weight range that provides sufficient binder strength while preventing gelation and precipitation, thereby maintaining solution stability.
2Reliability
If the molecular weight of the polymer is increased to suppress electrode expansion and contraction, then the cycle property is improved, but it becomes difficult to maintain the stability of the binder solution
Solution Approach 1:
The patent resolves this contradiction by optimizing the molecular weight parameter to 100,000-1,000,000 and controlling the molecular weight distribution (Mw/Mn) to 20 or less. This parameter optimization enables the polymer to effectively suppress electrode expansion and contraction during cycling while maintaining binder solution stability by preventing gelation.
Solution Approach 2:
The patent employs composite materials by combining the polymer with specific additives including a carboxylic acid compound (0.1-10 parts by weight per 100 parts polymer) and a crosslinking agent. This composite approach enhances the polymer's ability to suppress electrode deformation while the additives help maintain solution stability through controlled interactions.
3Strength
If a polymer with high molecular weight is used to improve cycle property, then the electrode strength is enhanced, but the electrode slurry becomes unstable and prone to precipitation
Solution Approach 1:
The patent applies parameter changes by optimizing the polymer molecular weight to 100,000-1,000,000 and controlling molecular weight distribution (Mw/Mn) to 20 or less. This ensures the polymer provides sufficient electrode strength while preventing slurry instability and precipitation.
Solution Approach 2:
The patent introduces a carboxylic acid compound as an intermediary substance (0.1-10 parts by weight per 100 parts polymer) that mediates between the high molecular weight polymer and the slurry components. This intermediary enhances electrode strength while preventing aggregation and precipitation, maintaining slurry stability.
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 binder composition achieves high stability and improved cycle property by suppressing electrode expansion and contraction, preventing peeling and breakage, and maintaining uniform composition, thus enhancing the performance of non-aqueous electrolyte batteries.
Implementation Method 1
a binder composition for an electrode of a non-aqueous electrolyte battery
Implementation Method 2
suppression of deterioration caused by the expansion, contraction, deformation, etc. of the electrodes
Data Source
AI summary
The present invention relates to a binder composition for an electrode of a non-aqueous electrolyte battery, the binder composition comprising a polymer A containing 80% by weight or more and 99.9% by weight or less of a repeating unit derived from a monomer including a nitrile group and 0.1% by weight or more and 20% by weight or less of a repeating unit derived from an ethylenically unsaturated compound having no nitrile group, wherein the weight-average molecular weight of the polymer A is 500,000 to 2,000,000, and characterized in that the molecular weight distribution, i.e. Mw/Mn, of the polymer A is 13 or smaller, wherein Mw represents the weight-average molecular weight and Mn represents the number-average molecular weight of the polymer A.