Electrode Plate Binder Gradient for Clean Heat Pressing
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Solution Overview
Problem
The existing manufacturing method for electrode plates results in the electrode layer adhering to heat press portions during the heat pressing process, leading to detachment from the current collecting foil, and there is a need for improved charge and discharge characteristics in batteries.
Innovation Solution
A manufacturing method that forms a deposition layer with a lower binder content on the surface (second deposition layer) compared to the side (first deposition layer), reducing adhesion to heat press portions and enhancing lithium ion mobility by using a heat pressing device with a pair of heating rollers or plates, and forming composite particles with smaller binder diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the deposition layer is formed with uniform binder content throughout, then the electrode layer has sufficient adhesion to the current collecting foil, but the surface of the electrode layer adheres to the heat press portion during heat pressing and detaches from the current collecting foil
Solution Approach 1:
The patent applies local quality by creating a non-uniform binder distribution within the deposition layer. Specifically, the binder content is higher near the current collecting foil interface (first deposition layer) to ensure strong adhesion, and lower at the surface (second deposition layer) to prevent adhesion to the heat press portion. This spatial variation in binder concentration resolves the contradiction between needing strong internal adhesion and avoiding external adhesion during processing.
2Strength
If the binder particle diameter is large, then the binder effectively binds active material particles together, but the binder particles obstruct lithium ion insertion and detachment, worsening charge and discharge characteristics
Solution Approach 1:
The patent applies parameter changes by optimizing the binder particle diameter to a specific range (0.1 to 10 μm, preferably 1 to 5 μm). This parameter optimization balances two competing requirements: particles large enough to provide effective binding between active material particles, but small enough to minimize obstruction to lithium ion diffusion. The patent also changes the binder content ratio in different layers, with lower binder content (1-10 wt%) in the second deposition layer to improve lithium ion mobility while maintaining sufficient binding.
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 method prevents electrode layer detachment during heat pressing and improves charge and discharge characteristics in lithium-ion secondary batteries by reducing binder particle obstruction, allowing easier lithium ion insertion and detachment.
Implementation Method 1
there is further generated the electric potential difference between the current collecting foil and the mixed powder body supplied to the outer circumferential surface of the roller A. Owing to the thus generated electric potential difference, the mixed powder body is moved from the outer circumferential surface of the roller A to a surface of the current collecting foil by an electrostatic force
Implementation Method 2
the deposition-layer-formed current collecting foil is made to pass (to be applied with heating-roller pressing) between a pair of heating rollers (a first heating roller and a second heating roller) as the pair of the heat press portions, and thus the deposition layer is compressed in its thickness direction and the binder particles included in the deposition layer are softened and molten
Data Source
AI summary
A manufacturing method for an electrode plate and an electrode plate are provided. The method includes deposition-layer forming to form a deposition layer in which active material particles and binder particles are deposited on a surface of a current collecting foil and heat pressing to form an electrode layer on the surface of the current collecting foil by heating and compressing a deposition-layer-formed current collecting foil having the deposition layer on the surface of the current collecting foil. The deposition layer includes a first deposition layer placed on a side of the current collecting foil and a second deposition layer constituting a surface of the deposition layer. The deposition-layer forming includes forming the deposition layer in which a content rate of the binder particles in the second deposition layer is lower than a content rate of the binder particles in the first deposition layer.