Push-Breaking Electrode Separation to Prevent Shorts and Cracks
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Solution Overview
Problem
Existing methods for manufacturing lithium secondary batteries face challenges in separating layered electrode sheets into desired dimensions while preventing inter-layer short circuiting and crack formation, as they often result in structural layer commingling and stress concentration.
Innovation Solution
A push-breaking device with a cutting blade tool that moves relative to a placement stand, featuring a rake angle of 15° to 30° and a relief angle of 5° to 15°, and a clearance length of 10% to 35% of the electrode sheet, which pushes and bends protruding regions to separate the electrode sheets, reducing the likelihood of inter-layer short circuiting and crack generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shearing operation based on meshing of upper and lower linear blades is used to cut the electrode, then the electrode can be separated into desired dimensions, but the sheared surface and blade side surface rub against each other causing structural layers to commingle and inter-layer short circuiting to occur
Solution Approach 1:
The patent replaces the traditional shearing mechanism with a push-breaking mechanism. The upper blade pushes the electrode material between itself and the lower blade, causing the material to break rather than shear. This substitution eliminates the rubbing action between blade surfaces and electrode layers that causes short circuiting, while still achieving precise separation at the designated cut line.
Solution Approach 2:
Instead of using the meshing action of two blades moving toward each other (conventional approach), the patent inverts the approach by having one blade (upper blade) push the material against a stationary or slower-moving lower blade. This reversal of the cutting mechanism eliminates the harmful rubbing contact while maintaining cutting effectiveness.
2Productivity
If the upper blade is lowered to push and separate the electrode base material, then the electrode can be divided into first and second electrodes, but stress concentration occurs leading to crack formation
Solution Approach 1:
The patent applies local quality by concentrating the pushing action at a specific location (the cut line) rather than distributing it across the entire electrode. The upper blade applies force locally at the designated separation point, causing the electrode to break cleanly at that specific location without creating stress concentrations that would lead to cracks elsewhere in the structure.
3Ease of manufacture
If a 90° blade tip angle is used for the cutting edge, then the blade structure is simple and easy to manufacture, but the cutting edge causes rubbing contact with the electrode surface leading to layer commingling
Solution Approach 1:
The patent changes the blade tip angle parameter from the conventional 90° to an acute angle (less than 90°). This parameter change modifies the cutting mechanism from shearing to push-breaking, eliminating the rubbing contact between the blade and electrode surface while still achieving clean separation. The acute angle allows the blade to more effectively push the material between the blades rather than scrape against it.
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 device effectively separates layered electrode sheets into desired dimensions while suppressing inter-layer short circuiting and crack formation, ensuring the integrity of the battery components during charging and discharging.
Implementation Method 1
the push-breaking device pushes and bends, and breaks, a portion of a protruding region... of the layered electrode sheet, which is pressed by the pressing mechanism
Implementation Method 2
a pressing mechanism pressing the layered electrode sheet placed on the placement stand
Data Source
AI summary
A push-breaking device has: a placement stand; a pressing mechanism; and at least one cutting blade tool. By the cutting blade tool, which moves along a first direction with respect the placement stand, the device pushes and bends, and breaks, a portion of a protruding region, which protrudes outward from the placement stand and the pressing mechanism, of the layered electrode sheet, which is pressed by the pressing mechanism in a second direction. An angle of a blade portion of the cutting blade tool with respect to the second direction is 15°-30°. An angle of the blade portion with respect to the first direction is an acute angle. A length, in the second direction, of a clearance between the blade portion and an end, at the cutting blade tool side, of the placement stand is 10%-35% of a length of the layered electrode sheet in the first direction.