Folded Separator Electrode Assembly for Battery Heat-Shrink Safety
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Solution Overview
Problem
Conventional electrode assemblies in lithium secondary batteries face safety issues due to thermal contraction of separators under high-temperature conditions, leading to electrical short circuits and potential ignition or explosion, especially when using cathode active materials with high nickel content.
Innovation Solution
The electrode assembly design includes adhering and folding separators to wrap around the cathode and anode plates, with an insulating tape covering the folded parts, to minimize thermal contraction and prevent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional coating method is used to form a protective coating layer on the aluminum foil, then the coating layer can provide corrosion protection, but the coating layer contains pinholes that reduce protection effectiveness and require additional protective layers
Solution Approach 1:
The patent replaces conventional mechanical coating methods (such as dip-coating or spray-coating) with an atomic layer deposition (ALD) process. This substitution enables the formation of a pinhole-free aluminum oxide coating layer on the aluminum foil, eliminating the coating defects and reducing the number of protective layers needed while improving corrosion protection effectiveness.
2Volume of moving object
If the separator is made thinner to reduce battery size, then the battery volume decreases, but the risk of internal short circuit increases
Solution Approach 1:
The patent applies composite material structure by combining the separator with an aluminum foil layer that has a pinhole-free aluminum oxide coating. This composite structure provides both the thin profile needed for compact battery volume and the enhanced protective barrier that prevents internal short circuits, effectively resolving the contradiction between size reduction and safety.
3Device complexity
If the aluminum foil is used without protective coating to reduce manufacturing complexity, then the number of layers decreases, but the aluminum foil undergoes chemical changes during battery operation that affect performance
Solution Approach 1:
The patent replaces conventional thick protective coating systems with a thin, pinhole-free aluminum oxide layer formed through atomic layer deposition. This substitution maintains chemical stability of the aluminum foil during battery operation while minimizing the number of additional protective layers required, thus reducing manufacturing complexity.
4Ease of manufacture
If conventional coating methods are used on aluminum foil, then the coating can be applied, but the coating forms pinholes that require additional protective layers increasing complexity
Solution Approach 1:
The patent replaces conventional coating application methods with atomic layer deposition (ALD) technology. This substitution enables the formation of a pinhole-free aluminum oxide coating layer in a single process step, eliminating the need for additional protective layers and reducing overall device complexity while maintaining ease of manufacture.
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 design enhances safety by reducing the risk of ignition and explosion, even under high-temperature conditions, while allowing for high-capacity and high-energy density batteries using nickel-rich cathode materials, and facilitates smooth assembly into battery cases.
Implementation Method 1
it has been attempted to form an aluminum oxide coating layer on an aluminum foil by anodization
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The present disclosure relates to an electrode assembly and a secondary battery including the same, and more particularly, to an electrode assembly and a secondary battery that can improve the safety of secondary batteries even under a high-temperature and heat-shrinkage environment of the separator. The electrode assembly includes a cathode plate, an anode plate corresponding to the cathode plate, and first and second separators that are disposed adjacent to each other with the cathode plate or the anode plate interposed therebetween, wherein at least one end of the first separator is adhered to at least one end of the second separator along the longitudinal direction of the cathode plate and the anode plate, wherein at least one end of the first and second separators is folded so as to wrap the cathode plate or the anode plate, and wherein the electrode assembly further includes an insulating tape covering the folded part of the first and second separators.