Lithium Battery Electrode Dewatering to Prevent Drying Defects
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Solution Overview
Problem
Existing electrode manufacturing processes for lithium secondary batteries face challenges in maximizing productivity while maintaining performance due to issues like skinning and binder migration during rapid drying, which deteriorate electrode quality.
Innovation Solution
A dewatering process inspired by paper manufacturing is applied to electrode manufacturing, involving the use of a porous substrate to remove a significant amount of solvent before drying, followed by lamination and pressing with an electrode current collector to enhance adhesion and further solvent removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solvent casting method is used to manufacture an electrode, then the manufacturing process is simple, but the electrode structure is not uniform and contains organic solvent residues
Solution Approach 1:
The manufacturing process is divided into two distinct stages: first forming a green sheet with uniform slurry distribution, then drying it to form the final electrode. This segmentation allows each stage to be optimized independently, ensuring structural uniformity while maintaining process simplicity.
Solution Approach 2:
The slurry is prepared and applied to the collector in advance to form a uniform green sheet before drying. This preliminary action ensures that the active material, conductor, and binder are uniformly distributed throughout the electrode structure before the drying process begins, preventing non-uniformity issues.
2Ease of manufacture
If a solvent casting method is used to manufacture an electrode, then the manufacturing process is simple, but organic solvent residues remain in the electrode
Solution Approach 1:
The organic solvent is completely extracted from the electrode through a controlled drying process. The green sheet is dried at a temperature below the decomposition point of the active material, allowing the solvent to evaporate completely and leave behind a uniform electrode structure without residual solvents.
3Productivity
If high concentration slurry is used, then less slurry is needed and coating is easier, but the electrode dries slowly and structure becomes non-uniform
Solution Approach 1:
The concentration of the slurry is optimized to a specific range (60-80 wt% of total weight) that balances coating efficiency with drying performance. This parameter optimization ensures that the slurry is concentrated enough for efficient coating but not so concentrated that drying becomes problematic, maintaining structural uniformity throughout the electrode.
4Productivity
If the electrode is dried at high temperature, then drying is faster, but the active material may decompose
Solution Approach 1:
The drying temperature is controlled to remain below the decomposition temperature of the active material while maintaining efficient drying rates. This temperature parameter optimization ensures complete solvent removal and uniform electrode formation without compromising the integrity or performance of the active material.
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 significantly shortens drying time, improves adhesive strength, and maintains electrochemical properties, resulting in higher productivity and better electrode performance without surface drying issues.
Implementation Method 1
coating a slurry on a current collector to form a green sheet
Implementation Method 2
drying the green sheet to manufacture an electrode
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5
AI summary
The present invention relates to a method for manufacturing an electrode for a lithium secondary battery, wherein, at the time of manufacturing of an electrode for a lithium secondary battery, a drying speed can be reduced through the steps of: applying a dewatering process using a porous substrate to remove a considerable amount of solvent from electrode slurry in advance; performing pressurization in a state of the porous substrate, an electrode layer, and an electrode current collector; performing additional dewatering; and separating the porous substrate from the electrode layer and then drying the electrode layer, and thus the electrode productivity can be maximized without degradation of electrode performance.