Laminate Layer Edge Structure for Uniform Roll Press Density
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Solution Overview
Problem
Conventional laminate structures experience a low volume density region during the transition from one region to another when pressed by a roll press device, leading to degradation in capacitance and cycling characteristics, particularly in lithium ion secondary batteries.
Innovation Solution
A laminate structure with a substrate having a first and second layer, where the end portions of the layers are inclined or have a stair shape, and a roll press device with an auxiliary roll positioned above or below a virtual plane to prevent the occurrence of low volume density regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If press is continually performed from the first region to the second region by a pair of press rolls, then the laminate structure can be efficiently produced, but a low volume density region occurs in the transition area causing degradation in capacitance and cycling characteristics
Solution Approach 1:
The pressing process is divided into multiple regions: a first region where only the first layer is formed, a second region where both first and second layers are formed, and a transition region between them. By segmenting the pressing operation and applying different pressing conditions in each region, the invention prevents the formation of low volume density regions while maintaining continuous production efficiency.
Solution Approach 2:
Different pressing conditions are applied to different regions of the laminate structure. In the transition region, the pressing force or speed is adjusted locally to ensure uniform volume density, while other regions maintain standard pressing parameters. This local quality adjustment eliminates the harmful low volume density region without compromising overall production efficiency.
2Manufacturing precision
If the end surface of the second layer is positioned closer to the central portion side than the first layer, then the press state change in the transition region is reduced, but the structural complexity increases
Solution Approach 1:
The invention employs an asymmetric configuration where the end surface of the second layer is positioned closer to the central portion side of the substrate than the end surface of the first layer. This asymmetric arrangement optimizes the press state transition and prevents low volume density region formation. The asymmetry is deliberately designed to improve pressing uniformity while managing structural complexity.
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 solution effectively prevents the formation of low volume density regions, ensuring consistent volume density across the laminate structure and improving the capacitance and cycling characteristics of lithium ion secondary batteries.
Implementation Method 1
an auxiliary roll that is disposed on at least one of upstream and downstream of the pair of press rolls... a laminate structure contact surface of the auxiliary roll is positioned above or below a virtual plane that the laminate structure includes when the laminate structure passes between the pair of press rolls
Data Source
AI summary
A laminate structure includes a substrate; a first layer provided on a first surface of the substrate; and a second layer provided on a second surface of the substrate. The first layer includes a first end portion and a second end portion along a width direction of the substrate, the second layer includes a third end portion and a fourth end portion along the width direction of the substrate, the first end portion is opposite to the third end portion, the second end portion is opposite to the fourth end portion. An end surface of the third end portion includes an inclined surface or a stair shape or a combined shape of the inclined surface and the stair shape.