Battery Cell Insulation Structure for Separator Shrinkage
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Solution Overview
Problem
Secondary batteries, particularly lithium-sulfur and lithium metal batteries, face issues of internal short circuits and thermal runaway due to separator shrinkage at high temperatures, leading to potential ignition and explosion, and capacity loss due to insulating areas formed on electrode plates.
Innovation Solution
A battery cell design featuring insulating members with non-adhesive surfaces on lithium or lithium alloy electrode plates, using materials like polyimide and polyethylene, to prevent short circuits and maintain capacity by ensuring non-adhesive contact with electrode plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive insulating members are used to prevent short circuits, then safety against short circuits is improved, but battery capacity decreases due to insulating areas formed on electrode plates
Solution Approach 1:
The insulating member is designed with differentiated surface properties: a first surface in contact with the electrode plate has non-adhesive properties to prevent capacity loss, while a second surface facing the opposite electrode provides insulation. This local quality differentiation resolves the contradiction by ensuring insulation function without forming harmful insulating areas on the electrode plate surface.
Solution Approach 2:
The insulating member acts as an intermediary element positioned between the first electrode plate and the second electrode plate. It provides the necessary insulation function to prevent short circuits while its non-adhesive first surface ensures it does not form insulating areas on the electrode plate, thus maintaining battery capacity.
2Reliability
If insulating members are placed on electrode plates to prevent short circuits, then safety is improved, but device complexity increases
Solution Approach 1:
The insulating member is designed to perform multiple functions simultaneously: it provides electrical insulation between electrodes, prevents short circuits during separator shrinkage, and maintains electrode plate surface quality through its non-adhesive first surface. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity.
Solution Approach 2:
The insulating member is implemented as a thin film structure with differentiated surface properties. This thin film approach provides necessary insulation and protection functions without adding significant structural complexity or volume to the battery assembly.
3Reliability
If separator is used to separate electrodes, then short circuit prevention is improved, but reliability decreases at high temperatures due to separator shrinkage
Solution Approach 1:
The insulating member is pre-installed on the first electrode plate before battery assembly, creating a permanent insulation barrier. This preliminary action ensures that even when the separator shrinks at high temperatures, the electrodes cannot come into contact, thus maintaining reliability under thermal stress conditions.
Solution Approach 2:
The insulating member serves as a protective cushioning element that prevents the harmful effect of separator shrinkage at high temperatures. By providing a permanent insulation barrier beforehand, it cushions against the potential short circuit risk that arises when the separator contracts due to thermal expansion.
Data Source
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AI summary
Provided is a battery cell comprising: at least one first electrode plate; at least one second electrode plate having the opposite polarity of the at least one first electrode plate; at least one separator disposed between the at least one first electrode plate and the at least one second electrode plate; and at least one insulation member mounted on the at least one first electrode plate, wherein the at least one insulation member includes a non-adhesive surface in contact with the at least one first electrode plate.