Electrode Sheet Laser Cutting to Prevent Separator Ridge Formation
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Solution Overview
Problem
The existing methods for cutting electrode sheets in secondary batteries with stacked electrode bodies often result in ridge-shaped protrusions on the separators due to overheating, leading to uneven electrode bodies with height differences between the center and edges.
Innovation Solution
A laser-based cutting apparatus that uses a first laser beam to cut the separator with low output power and a second laser beam to cut the electrode composite material layer, with the second laser beam having higher output power and a different wavelength, allowing for precise control to minimize the formation of raised portions in the cut area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is used to cut the electrode composite material layer, then the cutting speed and efficiency are improved, but the active material particles scatter to the outside causing the separator to melt and break
Solution Approach 1:
The laser beam is divided into two separate beams with different wavelengths: a first laser beam (e.g., CO2 laser at 10.6 μm) that is absorbed by the separator to cut it, and a second laser beam (e.g., fiber laser at 1.06 μm) that is absorbed by the electrode composite material layer to cut it. This segmentation allows each laser beam to target specific materials without causing harmful effects to other layers, thus maintaining separator integrity while achieving efficient cutting of the electrode material.
Solution Approach 2:
Different regions of the sheet stack are treated with different laser beams based on their material properties. The separator region is irradiated with the first laser beam wavelength optimized for separator absorption, while the electrode composite material layer region is irradiated with the second laser beam wavelength optimized for electrode material absorption. This local quality approach ensures that each material is cut by the most suitable laser wavelength, preventing unwanted heating and particle scattering that would damage the separator.
2Ease of manufacture
If the separator is heated to facilitate cutting, then the cutting process is improved, but the separator melts and breaks forming ridge-shaped portions
Solution Approach 1:
The heating function is segmented between two different laser beams with different wavelengths. The first laser beam provides controlled heating for separator cutting at lower temperatures, while the second laser beam provides higher energy for electrode material cutting. This segmentation prevents excessive temperature rise in the separator that would cause melting and ridge formation.
Solution Approach 2:
The wavelength parameter of the laser beam is changed to match the absorption characteristics of different materials. By using a first laser beam with a wavelength absorbed by the separator and a second laser beam with a wavelength absorbed by the electrode material, the heating efficiency is optimized for each material separately, allowing the separator to be cut without excessive temperature rise that would lead to melting and breakage.
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 approach effectively suppresses the formation of raised portions on the separators, ensuring a flat and even electrode sheet that can be stacked without height discrepancies, improving the manufacturing process for power storage devices.
Implementation Method 1
irradiating the separator of the sheet stack with a first laser beam having a wavelength to be absorbed by the separator... and irradiating the sheet stack having been irradiated with the first laser beam with a second laser beam having a wavelength to be absorbed by the electrode composite material layer
Data Source
AI summary
Provided is an electrode sheet manufacturing method including preparing a sheet stack including an electrode composite material layer and a separator provided on the electrode composite material layer, irradiating the separator of the sheet stack with a first laser beam having a wavelength to be absorbed by the separator, and moving an irradiation position of the first laser beam relative to the sheet stack. The method further includes irradiating the sheet stack having been irradiated with the first laser beam with a second laser beam having a wavelength to be absorbed by the electrode composite material layer, and moving an irradiation position of the second laser beam relative to the sheet stack, wherein the irradiation position of the second laser beam moves so as to follow a track of the irradiation position of the first laser beam.