Crowned Electrode Rolling Roll for High-Density Battery Sheets
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Solution Overview
Problem
Conventional rolling processes for secondary battery electrodes are limited in increasing energy density due to the constraints of rolling roll diameter and pressure distribution, leading to reduced contact area and pressure on the electrode sheet, which inhibits high-density rolling and affects the energy density of the battery.
Innovation Solution
A rolling apparatus with a unique rolling roll design featuring a central portion that protrudes more towards the electrode sheet than the end portions, coupled with a support structure that includes four-row roller bearings and refrigerant cooling to maintain consistent pressure and prevent end portion contact, allowing for higher density rolling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a rolling roll with a large diameter is used to improve rolling performance, then the contact area with the electrode sheet increases, but the pressure applied to the electrode sheet decreases, limiting high-density rolling
Solution Approach 1:
The rolling roll is designed with a crown shape where the central portion has a larger diameter than the end portions. This creates local variation in pressure distribution, concentrating higher pressure on the central portion of the electrode sheet while maintaining adequate contact area through the overall large diameter of the roll.
Solution Approach 2:
The rolling roll employs an asymmetric diameter profile along its axial direction, with the central portion protruding more toward the electrode sheet than the end portions. This asymmetric geometry enables differential pressure application across the width of the electrode sheet, optimizing both contact area and pressure distribution.
2Stress or pressure
If force applied to the electrode sheet is increased to improve mixture density, then the pressure on the electrode sheet increases, but the contact area decreases due to the large diameter of the rolling roll
Solution Approach 1:
The crown-shaped rolling roll concentrates the applied force on the central portion of the electrode sheet through its larger diameter at the center. This local quality variation ensures high pressure where it is most needed for density improvement while maintaining sufficient overall contact area through the extended end portions.
3Stress or pressure
If the rolling roll is designed with a crown curved portion to improve pressure distribution, then the central portion pressure increases, but the end portions may contact each other causing instability
Solution Approach 1:
The rolling roll features an asymmetric diameter profile where the central portion has a larger diameter than the end portions. This asymmetric design concentrates pressure on the central portion of the electrode sheet while the smaller end portions prevent excessive protrusion that could cause the rolling rolls to contact each other, thereby maintaining rolling stability.
Solution Approach 2:
The rolling roll employs specific dimensional parameters for the crown shape, with the central portion diameter being larger than the end portion diameters by a controlled amount. This parameter optimization ensures adequate pressure distribution on the electrode sheet while preventing the rolling rolls from making contact, thus maintaining system reliability.
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 apparatus achieves improved energy density in secondary batteries by ensuring uniform pressure distribution and preventing end portion contact, reducing breakage and extending the rolling roll's lifespan while enhancing mixture density.
Implementation Method 1
a support structure that includes four-row roller bearings and refrigerant cooling to maintain consistent pressure and prevent end portion contact
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A rolling apparatus for a secondary battery electrode sheet, may include: a transfer unit transferring an electrode sheet having an electrode mixture layer applied to at least one surface thereof in a first direction; a rolling roll pressing the electrode sheet in a second direction, intersecting the first direction; and a support portion coupled to a rotational axis of the rolling roll to support rotation of the rolling roll, wherein the rolling roll may have a shape in which a central portion thereof in an axial direction protrudes further toward the electrode sheet than both end portions of thereof in an axial direction.