Rechargeable Battery Cap Plate Welding Deformation Control
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Solution Overview
Problem
Existing rechargeable batteries face issues with cap plate deformation during the welding process of the vent member, leading to instability in the coupling between the cap plate and the case, which can result in reduced battery performance and increased production costs.
Innovation Solution
The vent member and cap plate are welded with a separated unit positioned towards the center of the cap plate in the thickness direction, maintaining a specific distance from the outer side to minimize deformation, and the vent member is designed with a notch and stepped structure for efficient pressure relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the vent member is welded to the outer side of the cap plate, then the welding process is simple and direct, but the cap plate deforms significantly during welding
Solution Approach 1:
The patent moves the welded unit from the outer surface (2D plane) to the inner thickness direction (3D space), specifically positioning it at the center of the cap plate thickness. This dimensional shift allows the weld to be performed on the inner surface while maintaining adequate distance from the outer surface, thereby reducing deformation of the outer surface during welding.
Solution Approach 2:
The patent pre-establishes the position of the welded unit at the center of the cap plate thickness before the welding process begins. By predeterminedly setting the distance h1 between the welded unit and the outer surface to satisfy 0.1t1≦h1≦0.5t1, the design ensures that deformation is minimized from the outset, preventing rather than correcting the deformation issue.
2Strength
If the welded unit is positioned close to the outer side of the cap plate, then the coupling between vent member and cap plate is strong, but the cap plate deforms during welding
Solution Approach 1:
The patent resolves the conflict between weld strength and deformation by transitioning from surface-level welding to thickness-direction welding. The welded unit is positioned at the center of the thickness direction, creating an optimal balance where the weld remains strong while being sufficiently distant from the outer surface to minimize deformation.
Solution Approach 2:
The patent changes the positional parameter of the welded unit from the outer surface to the inner thickness direction, specifically setting the distance h1 to satisfy 0.1t1≦h1≦0.5t1. This parameter optimization ensures both adequate weld strength and minimal deformation by finding the optimal position within the cap plate thickness.
3Manufacturing precision
If the cap plate thickness is increased to reduce deformation, then deformation during welding is minimized, but the overall battery size and weight increase
Solution Approach 1:
Instead of increasing thickness to reduce deformation, the patent changes the welding position to the inner thickness direction. This allows the use of thinner cap plates while still achieving minimal deformation through proper welded unit positioning, thus avoiding the weight penalty of thicker materials.
Solution Approach 2:
The patent optimizes the positional parameter h1 of the welded unit within the thickness direction, setting it to satisfy 0.1t1≦h1≦0.5t1. This parameter optimization allows for reduced cap plate thickness while maintaining low deformation, thereby reducing battery weight without sacrificing manufacturing precision.
4Ease of manufacture
If the welded unit is formed on the outer side of the cap plate, then the welding process is straightforward, but the coupling between cap plate and case becomes unstable
Solution Approach 1:
The patent improves coupling stability by moving the welded unit from the outer surface to the inner thickness direction. This positional change in the thickness dimension allows for better mechanical coupling between the cap plate and case, as the weld is positioned to more effectively transfer and distribute mechanical loads, thereby enhancing overall coupling stability.
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 reduces cap plate deformation by about half, ensuring stable coupling and reducing production costs while maintaining performance, as shown in comparative examples.
Implementation Method 1
a welded unit, by which the vent member and the cap plate are welded together, is separately formed toward a center of the cap plate in a thickness direction from an outer side of the cap plate
Data Source
AI summary
A rechargeable battery including an electrode assembly, the electrode assembly including a positive electrode and a negative electrode; a case accommodating the electrode assembly; a cap plate coupled with the case; and a vent member welded to the cap plate, the vent member including a notch thereon, wherein a welded unit, by which the vent member and the cap plate are welded together, is separately formed toward a center of the cap plate in a thickness direction from an outer side of the cap plate so as to be spaced apart from the outer side of the cap plate.