Battery Electrode Binder Composition for Adhesion and Rate Performance
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Solution Overview
Problem
Conventional binder compositions and slurry compositions for non-aqueous secondary batteries fail to achieve a balance between high adhesiveness between the electrode mixed material layer and the current collector, and enhanced battery characteristics such as rate characteristics and high-temperature storage characteristics.
Innovation Solution
A binder composition for non-aqueous secondary battery electrodes is developed, comprising a particulate polymer with specific chemical composition and particle diameter, and a highly soluble polymer, which forms an electrode mixed material layer with high peel strength and improved battery characteristics by using a combination of particulate polymer A and highly soluble polymer B, where the particulate polymer includes an ethylenically unsaturated acid monomer unit and (meth)acrylic acid ester monomer units, and the highly soluble polymer includes nitrile group-containing monomer units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binder compositions are used to form electrode mixed material layers, then the adhesion between the electrode mixed material layer and current collector can be maintained, but the battery characteristics such as rate characteristics and high-temperature storage characteristics are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight distribution (Mw/Mn ratio between 1.05-2.0) and composition ratios of the binder polymer. The binder contains specific proportions of nitrile group-containing monomer units (10-50 mass%) and aromatic vinyl monomer units (50-90 mass%), with controlled molecular weight parameters, to simultaneously achieve high adhesion and improved battery characteristics including rate characteristics and high-temperature storage characteristics.
Solution Approach 2:
The patent uses composite materials by creating a binder composition with a copolymer containing multiple monomer units (nitrile group-containing, aromatic vinyl, and optionally carboxyl group-containing monomer units). This composite polymer structure combines the adhesive properties from nitrile groups with the flexibility and processability from aromatic vinyl units, achieving both strong adhesion and enhanced battery performance.
2Strength
If the adhesion between electrode mixed material layer and current collector is increased, then peel strength is improved, but the flexibility and rate characteristics of the battery may be compromised
Solution Approach 1:
The patent resolves this contradiction through parameter changes by controlling the molecular weight distribution (Mw/Mn ratio) and composition of the binder. The specific parameter range (Mw/Mn: 1.05-2.0, with Mn ≥ 10,000) provides optimal balance between chain entanglement for adhesion and chain mobility for flexibility, enabling high peel strength while maintaining electrode flexibility and rate characteristics.
Solution Approach 2:
The patent applies local quality by creating a binder with spatially distributed functional groups - nitrile groups providing localized adhesion points for strong bonding to both current collector and active material, while aromatic vinyl segments providing flexible regions that maintain electrode bendability and ion transport pathways, achieving both high peel strength and flexibility.
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 effectively enhances the adhesiveness and flexibility of the electrode, leading to improved rate characteristics and high-temperature storage characteristics of the secondary battery by ensuring strong adhesion and preventing degradation of the electrode active material.
Implementation Method 1
enhancing the adhesiveness between an electrode mixed material layer and a current collector
Implementation Method 2
the highly soluble polymer includes nitrile group-containing monomer units
Data Source
AI summary
A binder composition contains an organic solvent and a binder that includes a particulate polymer A and a highly soluble polymer B. The particulate polymer A includes an ethylenically unsaturated acid monomer unit in a proportion of not less than 1.0 mass % and not more than 10.0 mass % and a (meth)acrylic acid ester monomer unit in a proportion of not less than 30.0 mass % and not more than 98.0 mass %. The particulate polymer A includes two particulate polymers A1 and A2 having different volume-average particle diameters. The volume-average particle diameters D50A1 and D50A2 of these particulate polymers A1 and A2 satisfy a formula: D50A2>D50A1≥50 nm.