Battery Electrode Binder Composition for Peel Strength and Cycle Life
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes lack sufficient peel strength and cycle characteristics, necessitating an improvement in the adherence between the current collector and the electrode mixed material layer while maintaining battery performance.
Innovation Solution
A binder composition with a polymer A that includes a nitrile group-containing monomer unit in a proportion of 80.0 to 99.9 mass%, a weight-average molecular weight of 700,000 to 2,000,000, and components with molecular weights less than 500,000 in a proportion of less than 30%, along with a molecular weight distribution of less than 3.0, is used to enhance the peel strength and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binder compositions are used, then the electrode mixed material layer can be formed, but the peel strength between current collector and electrode mixed material layer is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the weight-average molecular weight (700,000 to 2,000,000) and molecular weight distribution (Mw/Mn of 2.0 to 3.0) of the nitrile rubber polymer. These specific parameter ranges optimize both the peel strength and cycle characteristics, resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent uses a copolymer composition containing nitrile rubber as the main component (80-99.9 mass%) combined with other elastomers (0.1-20 mass%). This composite material approach allows the binder to achieve both high peel strength and excellent cycle characteristics by combining the advantages of different polymer materials.
2Strength
If polymer molecular weight is increased to improve peel strength, then adherence improves, but cycle characteristics deteriorate
Solution Approach 1:
The patent resolves this contradiction by identifying an optimal parameter range for weight-average molecular weight (700,000 to 2,000,000) and molecular weight distribution (Mw/Mn of 2.0 to 3.0). Within this range, the polymer achieves sufficient chain length for strong adherence while maintaining enough chain mobility for good cycle characteristics, preventing both extremes.
Data Source
AI summary
A binder composition for a non-aqueous secondary battery electrode contains a polymer A. The polymer A includes a nitrile group-containing monomer unit in a proportion of not less than 80.0 mass% and not more than 99.9 mass%, has a weight-average molecular weight (Mw) of not less than 700,000 and not more than 2,000,000, and includes components having a molecular weight of less than 500,000 in a proportion of less than 30%.