Electrode Plate Binder Zoning for Slitting and Breakage Control
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Solution Overview
Problem
During the manufacturing process of secondary battery electrodes, defects occur due to differences in stretching force between the current collector and the coating layer, leading to decreased bonding force and breakage, particularly at the boundary between coated and uncoated regions, resulting in increased product defect rates.
Innovation Solution
An electrode plate with a mixture layer having alternating high and low binder content regions is used, where the high binder content regions are strategically placed for slitting to enhance bonding and prevent breakage, and a method involving stripe coating with a double slit coating apparatus to form these regions on the current collector layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrode current collector is transferred using a roll-to-roll process with transfer rollers, then the electrode manufacturing process can be automated and productivity is improved, but the stretching force difference between the current collector and coating layer causes decreased bonding force and breakage
Solution Approach 1:
The patent applies local quality by creating regions with different binder contents within the coating layer. High binder content regions are positioned at areas subject to greater stretching forces during roll-to-roll transfer, while low binder content regions are placed in areas with lesser stretching forces. This localized variation in binder content optimizes the bonding force distribution to match the stretching force distribution, preventing breakage while maintaining manufacturing automation.
2Productivity
If the electrode current collector is slit using a cutting process, then the electrode can be processed into specific shapes and productivity is improved, but the shearing force transmitted by the cutter decreases the adhesive force between particles causing breakage and debris generation
Solution Approach 1:
The patent positions high binder content regions at locations where slitting cuts will occur. The binder in these regions acts as an adhesive that holds particles together during the cutting process, preventing breakage and debris generation. This localized reinforcement at critical cutting zones allows for efficient electrode shape processing without compromising particle adhesion.
3Reliability
If the binder content is increased throughout the entire coating layer, then the bonding force and adhesive force are improved, but the amount of active material is reduced and manufacturing cost increases
Solution Approach 1:
Instead of uniformly increasing binder content across the entire coating layer, the patent implements local quality by concentrating higher binder content only in specific regions where stretching and cutting forces are applied. The majority of the coating layer maintains lower binder content, maximizing active material quantity while still providing sufficient bonding and adhesion at critical locations.
Solution Approach 2:
The coating layer is segmented into multiple regions with different binder contents based on the local mechanical stresses. High binder content regions are segmented at positions corresponding to maximum stretching forces and cutting zones, while low binder content regions occupy the remaining areas. This segmentation optimizes the balance between bonding strength and active material quantity.
Data Source
AI summary
The present invention relates to an electrode slurry coating device and method, wherein the heights of first and second slot die heads for discharging active material can be controlled according to time to improve process efficiency and reduce defect rates when forming an active material layer having a double layer structure.