Battery Electrode Binder Composition for Bending and Electrolyte Wetting
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes struggle to achieve both excellent bending resistance and good electrolyte solution injectability, leading to inadequate battery characteristics.
Innovation Solution
A binder composition comprising a polymer A with an aliphatic conjugated diene monomer unit in 86-95 mass% and a nitrile group-containing monomer unit in 1-14 mass%, and a polymer B with an aliphatic conjugated diene monomer unit in 20-80 mass% and an aromatic vinyl monomer unit, enhancing bending resistance and electrolyte solution injectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binder composition is used, then electrode bending resistance is insufficient, but electrolyte solution injectability deteriorates
Solution Approach 1:
The patent uses a composite binder system consisting of two specific polymers: Polymer A (aliphatic conjugated diene-nitrile copolymer with 86-95 mass% diene units) and Polymer B (aliphatic conjugated diene-aromatic vinyl copolymer with 20-80 mass% diene units). This composite material approach allows the binder to simultaneously provide mechanical strength for bending resistance and appropriate porosity for electrolyte penetration, resolving the contradiction between these two properties.
Solution Approach 2:
The patent precisely controls the compositional parameters of the binder polymers, specifically the mass percentage of aliphatic conjugated diene monomer units (86-95% for Polymer A, 20-80% for Polymer B) and the presence of nitrile or aromatic vinyl groups. These parameter changes optimize the balance between mechanical properties (bending resistance) and transport properties (electrolyte injectability), allowing both requirements to be satisfied simultaneously.
2Strength
If binder composition is optimized for bending resistance, then electrode adhesion improves, but electrolyte penetration is hindered
Solution Approach 1:
The dual-polymer binder system creates a composite structure where Polymer A provides strong adhesion through its nitrile groups while Polymer B contributes to porosity and electrolyte wettability through its aromatic vinyl units. This composite material design enables simultaneous achievement of strong electrode adhesion and adequate electrolyte penetration.
Solution Approach 2:
The binder composition exhibits local quality differentiation at the molecular level: the nitrile-containing segments provide localized adhesion sites for strong electrode binding, while the aromatic vinyl-containing segments create localized hydrophobic regions that facilitate electrolyte access. This spatial differentiation of functional properties within the binder matrix resolves the contradiction between adhesion and penetration.
Data Source
AI summary
Provided is a binder composition for a non-aqueous secondary battery electrode that can form an electrode having excellent bending resistance and can ensure good electrolyte solution injectability in secondary battery production. The binder composition for a non-aqueous secondary battery electrode contains a polymer A. The polymer A includes an aliphatic conjugated diene monomer unit in a proportion of at least 86 mass% and not more than 95 mass%.