Wound Nonaqueous Battery Separators for Lower Reaction Force
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries with winding type electrode assemblies experience significant reaction forces due to shape loosening, limiting design freedom and requiring high-strength restraint components, which are typically made of metal materials.
Innovation Solution
The use of separators with a proportional limit of less than or equal to 10.2 MPa, combined with specific thickness and layering configurations, reduces the reaction force by promoting plastic deformation in a wider range, allowing the use of resin materials for restraint components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-strength restraint components are used to counteract large reaction forces, then the battery can maintain structural integrity, but the design freedom of the battery pack is decreased and device complexity increases
Solution Approach 1:
The patent changes the material parameter of the separator by controlling its proportional limit to be 10.2 MPa or less. This parameter change enables the separator to undergo plastic deformation that absorbs expansion forces, thereby reducing reaction forces and allowing the use of lighter restraint components with greater design freedom.
Solution Approach 2:
The separator acts as an intermediary element between the electrode assembly and the restraint component. By introducing plastic deformation in the separator, the patent creates a buffer mechanism that absorbs expansion forces, reducing the load on restraint components and enabling the use of resin materials instead of metal.
2Strength
If metal materials are used for restraint components to handle large reaction forces, then structural integrity is maintained, but the restraint component weight increases
Solution Approach 1:
By controlling the separator's proportional limit to 10.2 MPa or less, the patent creates a plastic deformation mechanism that reduces reaction forces. This parameter change enables the use of lighter resin materials for restraint components while maintaining sufficient structural integrity.
Solution Approach 2:
The patent converts the harmful effect of electrode assembly expansion into a beneficial plastic deformation of the separator. This deformation absorbs expansion forces that would otherwise require heavy metal restraint components, thereby reducing restraint component weight while maintaining strength.
3Stability of the object's composition
If the separator has high elastic modulus to maintain shape stability, then shape loosening is reduced, but reaction forces increase due to reduced plastic deformation
Solution Approach 1:
The patent changes the critical parameter of the separator's proportional limit to 10.2 MPa or less, which enables plastic deformation. This parameter change allows the separator to balance shape stability during normal operation while undergoing controlled plastic deformation to absorb expansion forces and reduce reaction forces.
Solution Approach 2:
The patent applies partial plastic deformation to the separator rather than requiring complete elastic recovery. By allowing controlled plastic deformation in the separator, the patent achieves sufficient shape stability while reducing reaction forces through the absorption of expansion energy.
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 configuration significantly reduces reaction forces, enabling the use of resin materials for restraint components and maintaining battery performance, while minimizing shape loosening and enhancing output.
Implementation Method 1
Each of the first separator and the second separator has a proportional limit of less than or equal to 10.2 MPa. The proportional limit is measured in a compression test... It is considered that springback is less likely to occur at the portion at which the crease is formed.
Data Source
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AI summary
A nonaqueous electrolyte secondary battery includes an exterior package, an electrode assembly, and an electrolyte solution. The exterior package stores the electrode assembly and the electrolyte solution. The electrode assembly is shaped to have a flat shape. The electrode assembly includes a layered body. The layered body includes a first separator, a positive electrode plate, a second separator, and a negative electrode plate. The first separator, the positive electrode plate, the second separator, and the negative electrode plate are layered in this order. The electrode assembly is formed by spirally winding the layered body. Each of the first separator and the second separator has a proportional limit of less than or equal to 10.2 MPa. The proportional limit is measured in a compression test in a thickness direction of each of the first separator and the second separator.