Layered Battery Separator Welding for Gas Escape and Short-Circuit Suppression
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Solution Overview
Problem
In existing battery designs, gas accumulation between the separator and the positive electrode can lead to lithium metal precipitation, increasing the risk of short circuits during repeated charging and discharging.
Innovation Solution
A battery design featuring a layer-type electrode body with alternately layered positive and negative electrode sheets and separator sheets, where the separator sheets have discrete welded portions along one direction, facilitating gas escape and reducing accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive portions are formed on all sides of the separator to surround the entire positive electrode, then the separator structure is improved for electrode coverage, but gas accumulates between the separator and the positive electrode leading to lithium metal precipitation and potential short circuits
Solution Approach 1:
The continuous adhesive portion on the separator is divided into multiple discrete adhesive portions arranged in an array. This segmentation creates gaps between adhesive portions that allow gas to escape, preventing gas accumulation while maintaining electrode coverage. The separator structure is thus segmented to balance coverage with gas venting capability.
Solution Approach 2:
Different regions of the separator are given different properties: areas with adhesive portions provide strong electrode attachment, while areas with gaps between adhesive portions allow gas escape. This local differentiation of quality enables the separator to simultaneously achieve good electrode coverage and effective gas management in different locations.
2Reliability
If the separator completely surrounds the positive electrode, then electrode coverage is improved, but gas escape paths are blocked causing lithium metal precipitation
Solution Approach 1:
The separator's adhesive coverage is segmented into discrete portions rather than continuous coverage. This segmentation creates localized attachment zones while leaving interspace for gas migration, thereby maintaining sufficient electrode coverage without completely blocking gas escape paths.
Solution Approach 2:
The gaps between discrete adhesive portions act as intermediary channels that facilitate gas escape while the adhesive portions themselves maintain electrode coverage. These intermediary spaces serve as gas migration pathways without compromising the overall electrode-separator connection.
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 design effectively suppresses the occurrence of short circuits by ensuring gas generated between the separator and electrodes easily moves outside, reducing lithium metal precipitation on the electrode surfaces.
Implementation Method 1
gas generated between the separator and the positive electrode easily moves outside
Data Source
AI summary
A battery includes a layer-type electrode body, a laminate exterior body, a positive electrode tab, and a negative electrode tab. In the electrode body, a positive electrode sheet and a negative electrode sheet are alternately layered in a layering direction via a separator sheet. The positive electrode tab protrudes from the laminate exterior body toward one side in a first direction orthogonal to the layering direction. The negative electrode tab protrudes from the laminate exterior body toward the one or another side in the first direction. The electrode body has an overlap region in which only plural separator sheets overlap at both edge regions in a second direction orthogonal to the layering direction and to the first direction. At least one of the two overlap regions has plural welded portions at which the plural separator sheets are welded. The plural welded portions are discretely formed along the first direction.