Lithium-Ion Electrode Binder Composition for Stable Slurry Coating
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Solution Overview
Problem
The existing binder compositions for lithium ion battery electrodes suffer from insufficient sedimentation stability and aggregation in the slurry composition, leading to poor coatability and adhesion of the electrode mixture layer to the current collector.
Innovation Solution
A binder composition for lithium ion battery electrodes containing a poly(meth)acrylamide copolymer with specific monomer ratios and intrinsic viscosity, including 30 mol % to 80 mol % (meth)acrylamide monomer and 20 mol % to 70 mol % unsaturated carboxylic acid-containing monomer, with an intrinsic viscosity of 3.5 dL/g to 7.5 dL/g, enhancing sedimentation stability and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a water-soluble polymer containing (meth)acrylamide monomer and acid group-containing monomer is used as binder composition, then low-temperature characteristics are improved, but sedimentation stability becomes insufficient and aggregation occurs in slurry composition
Solution Approach 1:
The patent changes the molecular weight parameters of the water-soluble polymer to resolve the contradiction. Specifically, it sets the weight average molecular weight to 1,000,000 to 5,000,000 and viscosity average molecular weight to 500,000 to 2,000,000, with a specific molecular weight ratio. This parameter optimization maintains low-temperature performance while preventing aggregation and improving sedimentation stability in the slurry composition.
2Strength
If binder composition with higher adhesive force is used, then adhesion of electrode mixture layer to current collector is improved, but coatability of slurry composition deteriorates due to aggregation
Solution Approach 1:
The patent optimizes the molecular weight parameters of the binder polymer to achieve both high adhesion and good coatability. By setting weight average molecular weight to 1,000,000 to 5,000,000 and viscosity average molecular weight to 500,000 to 2,000,000, the binder provides sufficient adhesive force while maintaining slurry flowability and preventing aggregation, thereby ensuring excellent coatability.
3Stability of the object's composition
If poly(meth)acrylamide copolymer with specific monomer ratios is used, then sedimentation stability and coatability are improved, but adhesion strength may be compromised if molecular weight is not optimized
Solution Approach 1:
The patent simultaneously optimizes both monomer composition and molecular weight parameters. The copolymer contains 40-80 mol% (meth)acrylamide monomer and 20-60 mol% acid group-containing monomer, with weight average molecular weight of 1,000,000 to 5,000,000 and viscosity average molecular weight of 500,000 to 2,000,000. This dual optimization ensures that the binder provides both excellent sedimentation stability and strong adhesion strength.
Data Source
AI summary
The binder composition for lithium ion battery electrodes at least contains a poly(meth)acrylamide copolymer that is a polymer of a monomer component including a (meth)acrylamide monomer and an unsaturated carboxylic acid-containing monomer as monomer units. The monomer component includes 30 mol % to 80 mol % of the (meth)acrylamide monomer and 20 mol % to 70 mol % of the unsaturated carboxylic acid-containing monomer relative to 100 mol % of a total amount of the monomer component. The poly(meth)acrylamide copolymer has an intrinsic viscosity of 3.5 dL/g to 7.5 dL/g.