Stacked Battery Separator Folding for Short Circuit Prevention
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Solution Overview
Problem
Existing stacked lithium ion batteries face issues with internal short circuits due to shedding of active materials, which can lead to self-discharge, heat generation, and safety hazards, and previous solutions like tape application or heat-treated separators either reduce productivity or deteriorate battery performance.
Innovation Solution
A stacked secondary battery design featuring a laminated body with a first electrode, a second electrode of different polarity, and a porous separator, where the separator is folded into multiple layers to prevent active material shedding from reaching the collector, eliminating the need for tape application and heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tape is applied to the exposed positive electrode collector region to prevent short circuits, then reliability improves, but productivity deteriorates due to additional manufacturing steps and potential rework
Solution Approach 1:
The separator is folded into multiple layers in advance during electrode assembly formation, creating a built-in protective structure that prevents short circuits without requiring subsequent tape application or other post-assembly modifications. This preliminary structural preparation eliminates additional manufacturing steps and maintains high productivity while ensuring reliability.
2Reliability
If heat treatment is applied to the separator to prevent active material shedding, then reliability improves, but manufacturing complexity and time increase
Solution Approach 1:
The separator is pre-folded into multiple layers during electrode assembly formation, creating a mechanical barrier that retains active materials without requiring heat treatment or other complex post-processing steps. This preliminary structural configuration simplifies the manufacturing process while maintaining reliability.
3Reliability
If the separator is made thicker to prevent active material penetration, then reliability improves, but the battery volume increases and energy density decreases
Solution Approach 1:
Instead of increasing separator thickness in one dimension, the separator is folded into multiple layers, effectively increasing the protective path length through spatial arrangement. This dimensional transformation provides enhanced protection against active material penetration while maintaining the original separator thickness and minimizing battery volume increase.
4Reliability
If the separator is folded into multiple layers, then reliability improves by preventing active material shedding, but manufacturing precision requirements increase
Solution Approach 1:
The separator folding is performed as a preliminary step during electrode assembly formation, allowing the structure to be established while components are still accessible and manageable. This timing enables integration with existing assembly processes without requiring ultra-precise folding operations under constrained conditions.
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
This design effectively prevents short circuits between electrodes while maintaining productivity and battery performance, ensuring safer and more reliable operation.
Implementation Method 1
a portion of the porous separator facing the second region of the first electrode and the region of the second electrode to which the second electrode active material has been applied is folded into a plurality of layers
Data Source
AI summary
The present invention relates to a stacked secondary battery that includes a laminated body, the laminated body including: a first electrode (10) in which a first electrode active material (12) is applied to both surfaces of a sheet-shaped collector (11), the first electrode having a first region (11a) to which the first electrode active material has been applied and a second region (11b) to which the first electrode active material has not been applied; a second electrode (20) in which a second electrode active material (22) different in polarity from the first electrode active material is applied to both surfaces (21) of a sheet-shaped collector; and a porous separator (30), the first and second electrodes being stacked via the porous separator, the first and second electrodes being stacked via the porous separator. In the stacked secondary battery, there were problems that the active material is shed from the first electrode or the second electrode and passes through the separator, and thus a short circuit between the electrodes occurs during use. The present invention solves the above problems by folding a portion (31) of the porous separator of the stacked secondary battery that faces the second region (11b) of the first electrode and the region (22) of the second electrode, to which the second electrode active material has been applied, into a plurality of layers.