Crowned Rolling Roll for High-Density Battery Electrode Sheets
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Solution Overview
Problem
Conventional rolling processes for secondary battery electrodes, particularly cathode electrodes, are limited in increasing mixture density due to the constraints of the rolling roll diameter, leading to reduced pressure application and energy density limitations.
Innovation Solution
A rolling apparatus with a rolling roll design that protrudes centrally towards the electrode sheet, coupled with a support structure to maintain consistent pressure and prevent end contact, allowing for higher density rolling without breaking the electrode sheet.
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
Solution Approach 1:
The rolling roll employs a crown shape where the central portion has a different geometry than the end portions. Specifically, the central portion has a smaller radius of curvature, creating a localized high-pressure zone that concentrates rolling pressure on the electrode sheet while the end portions have larger radii to distribute load and prevent edge damage.
Solution Approach 2:
The invention transitions from a conventional cylindrical rolling roll to a crown-shaped rolling roll by modifying the cross-sectional geometry along the axial dimension. This dimensional change creates a curved surface profile that simultaneously achieves high central pressure and controlled end distribution, resolving the pressure-area trade-off.
2Manufacturing precision
If force applied to the electrode sheet is increased to improve mixture density, then the rolling pressure increases, but the electrode sheet breaks more frequently
Solution Approach 1:
The crown shape creates localized high pressure at the central portion for effective densification while the end portions with larger radii provide gradual pressure transition, preventing stress concentration that would cause electrode sheet breakage.
Solution Approach 2:
The curved surface profile of the crown shape预先 distributes the applied force in a way that cushions the electrode sheet from sudden stress concentration, particularly at the edges, thereby preventing breakage while maintaining high central pressure for densification.
3Area of stationary object
If the rolling roll diameter is increased to improve rolling performance, then the contact area increases, but the pressure application efficiency decreases
Solution Approach 1:
The crown shape concentrates the effective rolling pressure in the central portion where it is most needed for mixture densification, while the end portions with larger radii provide structural support and gradual load distribution, optimizing overall rolling efficiency.
Solution Approach 2:
The curved surface profile of the crown-shaped rolling roll creates optimal contact geometry that concentrates pressure where needed while maintaining stable contact across the electrode sheet width, improving rolling efficiency compared to a flat cylindrical surface.
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 a mixture density of 3.60 to 3.80 g/cc, enhancing the energy density of the cathode electrode and secondary battery, while reducing breakage frequency and extending the rolling roll's lifespan.
Implementation Method 1
a current collector (hereinafter referred to as an electrode sheet) coated with a mixture layer on both surfaces thereof is compressed while passing through a pair of rolling rolls in the rolling process
Implementation Method 2
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
Data Source
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.