Bi-cell Separator Edge Fusion for Secondary Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face stability issues due to separator shrinkage, leading to potential short circuits and increased manufacturing costs when using larger separators to prevent these issues.
Innovation Solution
A bi-cell design where the cathode and anode are alternately stacked with larger separators, and the edges of the separators are fused together using heat and pressure to form stable fused portions, reducing the need for oversized separators and minimizing shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator having a bigger size than the electrode is used to prevent short circuit, then the reliability of preventing short circuit is improved, but the volume of the secondary battery increases
Solution Approach 1:
The separator is divided into two distinct parts: a main body portion that contacts the electrodes and provides insulation, and edge portions that extend beyond the electrodes and are fused together to form fused portions. This segmentation allows the separator to prevent short circuits effectively while minimizing the volume increase, as the fused edge portions secure the separator without requiring excessive oversizing.
Solution Approach 2:
The edge portions of the separator are预先 extended beyond the electrodes and positioned to face each other before the actual assembly is completed. This preliminary positioning allows the edges to be fused together in advance, creating a secured structure that prevents short circuits without requiring the separator to be excessively large throughout the entire battery assembly process.
2Reliability
If a separator having a considerably larger size than the electrode is prepared to securely prevent short circuit, then the reliability of preventing short circuit is improved, but the manufacturing cost increases
Solution Approach 1:
The separator is segmented into a main body portion and edge portions, where only the edge portions are extended beyond the electrodes to form fused portions. This segmentation reduces the overall amount of separator material needed compared to using a uniformly large separator, thereby lowering manufacturing costs while maintaining reliable short circuit prevention through the fused edge structure.
Solution Approach 2:
The separator exhibits different dimensional characteristics in different regions: the main body portion is sized to match the electrode for cost-effective material usage, while the edge portions are locally extended to provide the necessary security against short circuits. This local differentiation of quality allows cost reduction without compromising reliability.
3Ease of manufacture
If the edges of the separator are not attached to the electrode, then the ease of manufacture is improved, but the stability of the separator is worsened
Solution Approach 1:
The separator is segmented such that the main body portion remains loosely positioned for ease of assembly, while the edge portions are specifically designed to be fused together to form stable fused portions. This segmentation allows the majority of the separator to be easily manufactured and assembled without complex attachment processes, while the edge portions provide the necessary stability through fusion.
Solution Approach 2:
The edge portions act as intermediary elements that are fused together to create a stable anchoring structure. This intermediary fusion provides stability to the separator without requiring the entire separator to be attached to the electrodes, thereby maintaining ease of manufacture for the main assembly process while ensuring separator stability through the fused edge portions.
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 bi-cell achieves improved stability with smaller separators, reducing the risk of short circuits, minimizing battery volume, and lowering production costs while maintaining equivalent performance.
Implementation Method 1
edges of an upper separator and edges of a lower separator, which face to each other having the cathode or the anode disposed therebetween, are attached to each other to form fused portions
Implementation Method 2
edges of an upper separator and edges of a lower separator, which face to each other having the cathode or the anode disposed therebetween, are attached to each other to form fused portions
Data Source
AI summary
Provided are a bi-cell for a secondary battery having improved stability which may reduce shrinkage of a separator, and a method of preparing the bi-cell. The bi-cell for a secondary battery having improved stability according to an exemplary embodiment of the present invention is characterized in that a cathode and an anode are alternatingly disposed in a state in which the cathode has one more layer than the anode or the anode has one more layer than the cathode, separators having a bigger size than the cathode and the anode and insulating the cathode and the anode are disposed between the cathode and the anode, and edges of an upper separator and edges of a lower separator, which face to each other having the cathode and the anode disposed therebetween, are attached to each other to form fused portions.