Separator Edge Welding for Battery Short Circuit Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power storage devices face issues with short circuits between positive and negative electrodes due to separator shrinkage, as the edge portion of the separator may be insufficiently thick when welded to the sealing member, leading to breakage and potential contact between electrodes.
Innovation Solution
A power storage device design where the separator's edge portion is sandwiched and joined to a melted-then-solidified resin material of the sealing member, with a material having a higher melting temperature than the resin, preventing displacement and breakage, and ensuring the separator remains interposed between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the edge portion of the separator is welded to the sealing member, then the separator is fixed and displacement is suppressed, but the separator thickness becomes insufficient and the separator breaks easily when it shrinks
Solution Approach 1:
The patent changes the material parameter of the separator by selecting a material with a melting point higher than the sealing member resin (e.g., polypropylene separator with melting point 160°C and sealing member with melting point 100°C). This parameter change allows the separator to maintain its shape during welding without melting, preventing thickness reduction and breakage while still enabling fixation through the welding process.
Solution Approach 2:
The patent applies prior cushioning by pre-selecting a separator material that can withstand the welding temperature without deforming. This beforehand preparation ensures that when the welding process occurs, the separator is already in a state that prevents it from melting or thinning, thus cushioning against the potential harm of breakage during subsequent shrinkage.
2Ease of manufacture
If the separator material has a low melting temperature, then it is easy to weld, but the separator melts and loses its shape when joined to the sealing member
Solution Approach 1:
The patent changes the melting temperature parameter of the separator material to be higher than the sealing member resin. This creates a temperature window where the sealing member can be welded (melted and solidified) while the separator remains solid and maintains its shape, thus resolving the contradiction between ease of welding and shape maintenance.
3Strength
If the separator is held by friction between the outer surface and melted-then-solidified portion, then joining strength is sufficient to prevent separation, but the separator may still shift during the welding process
Solution Approach 1:
The patent applies beforehand cushioning by designing the separator material to have a melting point significantly higher than the welding temperature. This ensures that during the entire welding process, the separator remains in a stable solid state that resists shifting, while the sealing member resin melts and solidifies to provide strong friction-based holding. The material selection cushions against positioning errors during manufacturing.
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 effectively suppresses short circuits by maintaining the separator's shape and preventing separation from the sealing member, ensuring reliable interposition between electrodes.
Implementation Method 1
the edge portion of the separator is joined to a melted-then-solidified portion of the resin material of the sealing member
Implementation Method 2
the sealing member holds the edge portion of the separator with friction between the outer surface of the edge portion of the separator and the melted-then-solidified portion
Implementation Method 3
the separator includes a material having a melting temperature higher than a melting temperature of a resin material of the sealing member, so that the edge portion of the separator may be joined to the melted-then-solidified portion in a state in which the shape of the edge portion is maintained without melting
Data Source
AI summary
A power storage device includes a positive electrode and a negative electrode facing each other, a separator disposed between the positive electrode and the negative electrode, the separator being porous, and a sealing member made of a resin and sealing a space between the positive electrode and the negative electrode. The separator includes a material having a melting temperature higher than a melting temperature of a resin material of the sealing member. The separator has an edge portion sandwiched and held in the sealing member in a state where the edge portion is joined to a melted-then-solidified portion of the resin material of the sealing member.