Battery Electrode Coating with Zoned Binder Distribution
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Solution Overview
Problem
The adhesion of the active material layer to the current collector in secondary battery electrodes deteriorates due to binder migration during the drying process, leading to increased interfacial resistance and limited lithium ion diffusion during fast charging, resulting in cell degradation.
Innovation Solution
A manufacturing method and apparatus that vary the ejection ratio of a first slurry with a higher binder content and a second slurry with a lower binder content onto a current collector, allowing for alternating regions of high and low binder content along the coating length, enhancing interfacial adhesion and fast charging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of binder is included in the active material slurry to improve adhesion, then interfacial adhesion is enhanced, but interfacial resistance increases and fast charging performance deteriorates
Solution Approach 1:
The patent applies local quality by creating alternating high-binder and low-binder regions along the coating length. The high-binder regions provide strong adhesion to the current collector, while the low-binder regions maintain low interfacial resistance for efficient lithium ion diffusion. This spatial variation in binder concentration allows simultaneous optimization of both adhesion strength and fast charging performance.
Solution Approach 2:
The patent segments the coating into multiple zones with different binder concentrations along the longitudinal direction. By controlling the ejection ratio of slurries with different binder contents, the coating is divided into alternating high-binder and low-binder regions, each serving distinct functions: adhesion enhancement and resistance reduction respectively.
2Strength
If binder migration occurs during drying to concentrate binder at the interface, then adhesion is improved, but lithium ion diffusion is limited and cell degradation occurs
Solution Approach 1:
The patent applies preliminary anti-action by pre-distributing binder in alternating high and low concentration regions before drying occurs. This preliminary arrangement prevents excessive binder migration during drying, as the low-binder regions are already designed to have lower binder content, thus preventing the formation of high-resistance zones that would cause cell degradation.
Solution Approach 2:
The patent creates local quality differences in binder distribution along the coating length, with alternating high-binder regions for adhesion and low-binder regions for ion diffusion. This localized control prevents uniform binder migration that would otherwise create harmful high-resistance zones throughout the entire coating.
3Reliability
If uniform binder distribution is maintained to reduce interfacial resistance, then fast charging performance is improved, but interfacial adhesion deteriorates
Solution Approach 1:
The patent deliberately creates non-uniform binder distribution through alternating high-binder and low-binder regions. The low-binder regions provide low interfacial resistance for fast charging, while the high-binder regions provide strong adhesion. This local quality variation resolves the contradiction by providing both properties in different spatial zones.
Solution Approach 2:
The patent segments the coating into functional zones: high-binder segments for adhesion and low-binder segments for ion transport. This segmentation allows the electrode to exhibit both strong adhesion and low resistance properties simultaneously, despite the non-uniform binder distribution.
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 method achieves improved interfacial adhesion and fast charging performance by optimizing the binder distribution, allowing for concurrent enhancement of electrode stability and charging efficiency without requiring additional equipment.
Implementation Method 1
coating, by a coater, the first slurry and the second slurry ejected at the variable ejection ratio onto a current collector in a longitudinal direction of the current collector
Implementation Method 2
drying, by a dryer, the first slurry and the second slurry coated onto the current collector
Data Source
AI summary
A method for manufacturing an electrode for a secondary battery, includes: ejecting, by an ejector, a first slurry and a second slurry at a variable ejection ratio that varies in response to control signals from a controller; coating, by a coater, the first slurry and the second slurry ejected at the variable ejection ratio onto a current collector in a longitudinal direction of the current collector; and drying, by a dryer, the first slurry and the second slurry coated onto the current collector.