Secondary Battery Separator Tape Fixing
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Solution Overview
Problem
In secondary batteries, the exposure of electrode mixture layers due to separator turning or rising during thermocompression bonding can lead to micro-short circuits, especially when using separators with different thermal shrinkage rates, causing internal short circuits.
Innovation Solution
A secondary battery design featuring a separator with a tubular portion and attached tape at one end to prevent exposure of the electrode mixture layers, ensuring the separator covers the outermost surfaces and maintains the assembly's integrity during thermal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermocompression bonding is performed using a separator with two or more layers having different thermal shrinkage rates, then the bonding strength between separator and electrodes is improved, but the end of the separator turns up more, causing exposure of the electrode mixture layer
Solution Approach 1:
The patent applies preliminary action by attaching a fixing member to the separator before thermocompression bonding. This fixing member pre-restrains the separator end in the axial direction, preventing it from turning up during the subsequent thermal process. The separator is prepared in advance with this constraint mechanism, so when heating occurs, the end position is already secured, avoiding exposure of the electrode mixture layer while still allowing the bonding function to work effectively.
2Ease of manufacture
If the separator end is not secured, then the assembly process is simpler, but the electrode mixture layer may fall off and cause internal short circuit
Solution Approach 1:
The patent introduces an intermediary element - the fixing member - that acts as a mediator between the separator and the electrode assembly. This fixing member is attached to the separator end and serves as an intermediate constraint mechanism. It provides a simple yet effective solution by being a separate component that can be easily attached, maintaining assembly simplicity while reliably preventing the separator end from turning up and causing internal short circuits.
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
Prevents internal short circuits by securing the separator's position and preventing the mixture layer from falling off, thus enhancing the battery's reliability and preventing micro-short circuits.
Implementation Method 1
the separator includes a first layer and a second layer having a thermal shrinkage rate smaller than that of the first layer
Data Source
AI summary
This secondary battery is provided with an electrode body formed by laminating a positive electrode and a negative electrode with a separator interposed therebetween. The separator includes a first layer and a second layer having a lesser thermal shrinkage than the first layer, and has a tubular part that is formed in a tubular shape and that constitutes the outermost surface of the electrode body. The tubular part, of the separator, that constitutes the outermost surface of the electrode body has a tape stuck thereto in at least one end portion in the axial direction, the tape pressing the one end portion in the axial direction from one side to the other side in the lamination direction of the electrode body.