Laminated Battery Separator Fixing for Electrolyte Level Stability
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Solution Overview
Problem
The expansion of negative electrode active materials during discharge in laminated batteries causes deformation of the bag separator, leading to a gap between the positive and negative electrodes, which results in a drop in electrolyte level, reduced battery capacity, and shorter cycle life.
Innovation Solution
A laminated battery design where the enclosure member is formed by affixing a first resin film and a second resin film to each other, with the separator fixed to the peripheral edge of at least one of the resin films, preventing the separator from shifting and maintaining the electrolyte level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a bag separator is used to store negative electrode active material, then the negative electrode can be contained, but the separator deforms following volume expansion during discharge causing electrode misalignment
Solution Approach 1:
The separator is divided into two functional regions: a flexible bag portion that accommodates volume expansion of the negative electrode, and a rigid peripheral edge portion that is fixed to the enclosure member to maintain positional stability. This segmentation allows each region to perform its specific function without compromising the other.
Solution Approach 2:
Different portions of the separator are given different properties: the central bag region is made flexible to expand with the negative electrode, while the peripheral edge region is made rigid and fixed to prevent displacement. This local differentiation of mechanical properties resolves the contradiction between flexibility and stability.
2Stability of the object's composition
If the separator is allowed to deform freely, then volume expansion of negative electrode is accommodated, but gaps form between electrodes causing electrolyte level drop
Solution Approach 1:
The separator is segmented into a deformable bag portion and a fixed peripheral edge portion. The bag portion accommodates volume changes while the fixed edge portion prevents gap formation and maintains electrolyte level, avoiding the need for complex additional restraint mechanisms.
3Stability of the object's composition
If peripheral edge of separator is fixed to enclosure member, then separator position stability is improved, but manufacturing process becomes more complex
Solution Approach 1:
The peripheral edge of the separator is merged with the enclosure member through fixation (welding or adhesion). This integration simplifies the overall structure by combining the separator's restraint function with the enclosure member, eliminating the need for separate restraint components and reducing assembly steps.
Data Source
AI summary
Provided are a laminated battery capable of suppressing a level drop of an electrolyte caused by expansion of a negative electrode active material during discharge, and a manufacturing method for the laminated battery.An enclosure member of the laminated battery is constituted by affixing a first resin film and a second resin film to each other, and a separator is arranged inside the enclosure member between a positive electrode (for example, a first electrode) and a negative electrode (for example, a second electrode). A peripheral edge portion of the separator is fixed to a peripheral edge portion of the enclosure member (the first resin film or the second resin film).