Stacked Secondary Battery Separator Fold Layout to Prevent Swelling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In stacked secondary batteries, the folding of separators at the ends of electrodes leads to electrode deformation due to shrinkage and restoring forces, causing adverse effects such as swelling and potential short-circuits.
Innovation Solution
The separator is continuously folded with its folds positioned at a specified distance away from the ends of the electrodes, preventing direct contact and reducing the impact of shrinkage and restoring forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the separator is continuously folded at the ends of electrodes, then the separator length is reduced and manufacturing is simplified, but the electrodes are pressed at folds causing deformation and the stack swells
Solution Approach 1:
The harmful folds are extracted and relocated from the electrode regions to the non-electrode regions. The separator is folded only in the width-direction excess portions that do not overlap with electrodes, separating the folding function from the electrode-containing regions to eliminate the harmful pressing effect while maintaining the space-saving folding benefit.
Solution Approach 2:
The separator folds are deliberately positioned in advance to avoid the electrode regions. By planning the fold locations in the width-direction excess portions before assembly, the harmful pressing action on electrodes is prevented from occurring in the first place, while still achieving the separator length reduction.
2Device complexity
If the separator is continuously folded at the ends of electrodes, then the separator structure is simplified, but restoring forces at folds cause the stack to swell
Solution Approach 1:
The folds are extracted from the electrode regions and placed only in the width-direction excess portions. This separation removes the source of restoring forces that would otherwise act on the electrode stack, preventing stack swelling while maintaining the simplified continuous folding structure.
Solution Approach 2:
The width-direction excess portions serve as an intermediary zone that absorbs the folding function. These excess portions act as a buffer that accommodates the separator folds without transmitting the harmful restoring forces to the electrode stack, thereby preventing swelling.
3Volume of moving object
If the separator is folded at the ends of electrodes, then the separator fits within the electrode boundaries, but shrinkage presses the electrodes causing deformation
Solution Approach 1:
The folds are extracted and relocated to the width-direction excess portions that do not contain electrodes. This ensures that the separator shrinkage during operation does not press against the electrodes at fold locations, preventing electrode deformation and maintaining electrode integrity.
Solution Approach 2:
The separator width is segmented into two functional zones: the electrode-region portion that maintains proper positioning over electrodes, and the width-direction excess portion that accommodates the folds. This segmentation allows the separator to fulfill both positioning and folding requirements without compromising electrode integrity.
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 configuration minimizes the adverse effects of separator folding, such as electrode deformation and swelling, while also preventing short-circuits and reducing the length of the separator, thus lowering costs.
Implementation Method 1
A separator can be shrunk by heat
Implementation Method 2
when a separator is continuously folded, a restoring force acts at a folded part
Data Source
AI summary
There is provided a secondary battery where the occurrence of adverse effects due to folds of a continuously folded separator is reduced. A secondary battery includes a plurality of sheet-like positive electrodes, a plurality of sheet-like negative electrodes, and a belt-like separator placed between the positive electrodes and the negative electrodes. The positive electrodes and the negative electrodes are alternately stacked with the separator interposed therebetween. The separator is continuously folded to be interposed between the positive electrodes and the negative electrodes. Folds of the continuously folded separator are at least a specified distance away from ends of the negative electrodes.