Negative Electrode Binder Distribution for Battery Adhesion
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries have room for improvement in input characteristics, particularly in adhesion and reaction efficiency due to the limitations of binder distribution and surface coverage on graphite and carbon materials.
Innovation Solution
A negative electrode with a carbon material having a BET specific surface area greater than graphite, combined with a hydrophobic binder that covers the carbon material's surface more extensively than graphite, enhances adhesion and reaction efficiency by allowing internal battery reactions while maintaining good electrode plate adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional binder is used to improve adhesion of the mixture layer to the collector, then adhesion is improved, but input characteristic deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the binder coverage on different carbon materials. The hydrophobic binder selectively covers the surface of carbon material B (higher BET specific surface area) more than graphite, creating localized adhesion enhancement at the collector interface while preserving reaction sites on graphite particles. This selective coverage resolves the contradiction by improving adhesion locally without globally blocking reaction sites.
Solution Approach 2:
The patent changes the parameter of binder hydrophobicity and selectively adjusts the binder coverage ratio between different carbon materials. By using a hydrophobic binder and controlling the coverage ratio (binder on carbon material B / binder on graphite) to be 1.05 or more, the patent achieves improved adhesion while maintaining input characteristic, as the higher surface area carbon material provides more binder binding sites without blocking graphite reaction sites.
2Strength
If binder coverage on graphite is increased to improve adhesion, then adhesion is improved, but reaction efficiency deteriorates
Solution Approach 1:
The patent applies local quality by directing the binder primarily to carbon material B rather than graphite. The hydrophobic binder selectively adheres to the higher surface area carbon material B, creating localized adhesion at the collector interface while leaving graphite particle surfaces largely uncovered for efficient lithium ion reaction. This resolves the contradiction by decoupling adhesion function (handled by carbon material B) from reaction function (handled by graphite).
Solution Approach 2:
The patent uses a composite electrode structure combining graphite and carbon material B with different properties. Graphite provides high reaction efficiency with minimal binder coverage, while carbon material B provides adhesion support with higher binder coverage due to its larger surface area. The composite system resolves the contradiction by assigning different functional roles to different materials within the same electrode mixture layer.
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
This configuration significantly improves the input characteristic of non-aqueous electrolyte secondary batteries by optimizing binder distribution and surface coverage, leading to better adhesion and reaction efficiency.
Implementation Method 1
a coverage of particle surface of the carbon material with the binder is higher than a coverage of particle surface of the graphite with the binder
Data Source
AI summary
This non-aqueous electrolyte secondary battery is provided with: a wound electrode body which comprises a positive electrode, a negative electrode and a separator, and wherein the positive electrode and the negative electrode are wound into a roll, with the separator being interposed therebetween; and a non-aqueous electrolyte. The negative electrode comprises a negative electrode collector and a negative electrode mixture layer that is formed on the negative electrode collector. The negative electrode mixture layer contains graphite, a carbon material that has a BET specific surface area of 10 m2/g or more, said BET specific surface area being larger than that of the graphite, and a hydrophobic binder. The coverage of the particle surfaces of the carbon material by the binder is higher than the coverage of the particle surfaces of the graphite by the binder.