Step Portion Separation Film for Electrode Assembly
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Solution Overview
Problem
In electrode assemblies with a stacked and folded scheme, tension in the separation film between layers leads to degraded insertion properties and potential defects due to bending, particularly in the lower electrode with a larger area.
Innovation Solution
The electrode assembly is designed with a rectangular-shaped separation film that covers the step portion, with the film's thickness reduced to 90% or less, and tension is removed by elongating or cutting the film on the inclined surface, allowing it to conform to the electrode assembly's shape, thereby preventing tension generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a separation film is stretched tight to closely adhere to electrode surfaces in a stacked and folded scheme, then the film provides structural support and enables subsequent electrode stacking, but tension is generated in the separation film that degrades insertion properties and causes bending defects
Solution Approach 1:
The separation film is divided into a first separation film for the first electrode laminate and a second separation film for the second electrode laminate. This segmentation allows each film to be independently optimized - the first film can be stretched tight for structural support while the second film can be designed to relieve tension and prevent bending defects in the step portion.
Solution Approach 2:
Different regions of the separation film structure are given different properties. The first separation film has tensioned regions for structural support, while the second separation film has relaxed regions that conform to the step portion without generating harmful tension, creating local quality variations that solve both support and reliability requirements.
2Adaptability or versatility
If electrodes of different areas are stacked to form a step portion, then electrode assembly design flexibility is improved, but an inclined surface is formed that prevents close adhesion of the separation film and generates tension
Solution Approach 1:
The separation film structure is segmented into multiple films (first and second separation films) that can independently address different geometric challenges. The second separation film specifically addresses the step portion geometry, allowing the inclined surface to be accommodated without compromising overall manufacturing precision.
Solution Approach 2:
The solution addresses the two-dimensional adhesion problem on the inclined surface by introducing a third dimension - a stepped three-dimensional structure with the second separation film that conforms to the step portion, transforming the adhesion challenge from a flat surface problem to a volumetric fit problem.
Data Source
AI summary
There is provided an electrode assembly including a first electrode laminate having at least one or more electrode units having a first area, stacked therein, a second electrode laminate having at least one or more electrode units having a second area smaller than the first area, stacked therein, and a step portion provided by stacking the first electrode laminate and the second electrode laminate in a direction perpendicular to a plane and having a step formed due to a difference in areas of the first and second electrode laminates, the electrode assembly being characterized in that, the electrode unit is wound by a rectangular-shaped separation film such that at least a portion of the rectangular-shaped separation film covers the step portion of the electrode assembly, and a step having a shape identical to the step portion is formed.