Electrode Assembly Separators Tuned to Suppress Battery Bending
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Solution Overview
Problem
Secondary batteries experience bending phenomena during the activation process due to temperature non-uniformity, which affects the adhesion of separators to electrodes, leading to structural instability and reduced durability.
Innovation Solution
The electrode assembly incorporates separators with different adhesive properties, where the central portion has a lower adhesion temperature than the surface portion, minimizing the temperature difference and adhesion deviation between these regions, thereby reducing bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same separator is used throughout the electrode assembly, then the manufacturing process is simple, but temperature difference between surface and central portions causes bending phenomenon
Solution Approach 1:
The patent applies local quality by using different types of separators in different regions of the electrode assembly. Specifically, a first type of separator with adhesion maximized at a first temperature is used in the central portion, while a second type of separator with adhesion maximized at a second temperature is used in the surface portion. This regional differentiation compensates for temperature non-uniformity during the hot press process, preventing bending while maintaining manufacturing feasibility.
2Strength
If hot press process is applied to increase adhesion, then separator adhesion to electrodes is improved, but temperature non-uniformity causes bending phenomenon
Solution Approach 1:
The patent addresses the bending issue caused by hot press temperature non-uniformity by implementing local quality through region-specific separator selection. The central portion separators are optimized for lower temperatures where adhesion is maximized, while surface portion separators are optimized for higher temperatures. This ensures that despite the temperature gradient during hot pressing, both regions achieve adequate adhesion without causing bending.
Solution Approach 2:
The patent applies parameter changes by varying the adhesion temperature characteristics of separators across different regions. By selecting separators with different temperature-optimal adhesion properties for central versus surface portions, the patent compensates for the temperature gradient inherent in the hot press process, maintaining both strong adhesion and structural flatness.
3Stability of the object's composition
If separators with different adhesive properties are used in central and surface portions, then bending phenomenon is suppressed, but device complexity increases
Solution Approach 1:
The patent implements local quality by dividing the electrode assembly into central and surface portions, each equipped with separators optimized for their specific thermal environment. This regional differentiation suppresses bending caused by temperature non-uniformity during hot pressing, while the complexity increase is offset by the manufacturing efficiency gains from reduced defect rates and rework.
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 approach effectively suppresses the bending phenomenon, enhancing the durability and stability of the secondary battery by ensuring consistent adhesion across the electrode assembly during activation.
Implementation Method 1
the temperature at which the adhesion of the separators, positioned in the central portion of the electrode assembly, to the electrodes is maximized is lower than the temperature at which the adhesion of the separators, positioned in the other regions, to the electrodes is maximized
Data Source
AI summary
The present invention provides an electrode assembly in which positive electrodes and negative electrodes are alternately stacked with separators interposed therebetween and which includes two or more types of separators having different temperatures at which adhesion is maximized, wherein the temperature at which the adhesion of the separators, positioned in the central portion of the electrode assembly, to the electrodes is maximized is lower than the temperature at which the adhesion of the separators, positioned in the other regions, to the electrodes is maximized, and also a secondary battery including the electrode assembly.