Battery Can Seam Welding Structure for One-Step Cap and Collector Joining
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Solution Overview
Problem
The manufacturing process of cylindrical battery cells is labor-intensive and costly due to individual welding of the current collector plate, cap, and sidewall member, and existing methods struggle to maintain precise assembly, leading to potential damage from laser welding errors.
Innovation Solution
A welding structure that integrates the welding of the current collector plate and cap with the sidewall member into a single process, utilizing a triple welding technique to ensure alignment and close contact, preventing laser penetration into the can and enhancing weld durability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If individual welding processes are used for connecting the current collector plate to the cap and the cap to the sidewall member, then welding reliability is maintained, but production efficiency decreases and production costs increase
Solution Approach 1:
The patent combines three separate welding operations (current collector plate to cap, cap to sidewall member, and current collector plate to sidewall member) into a single integrated welding process. The cap and current collector plate are positioned to contact the sidewall member simultaneously, allowing all connections to be welded in one operation, thereby improving production efficiency while maintaining welding reliability through proper structural design.
Solution Approach 2:
The cap and current collector plate are pre-positioned in a specific configuration before the welding process begins. The cap is positioned to contact the sidewall member at a predetermined location, and the current collector plate is positioned to contact both the cap and sidewall member. This preliminary positioning ensures that when welding occurs, all components are correctly aligned, eliminating the need for multiple separate welding operations.
2Productivity
If laser welding is performed on crudely assembled components with gaps due to tolerances and assembly errors, then production speed increases, but the laser may penetrate directly into the can causing damage to the electrode assembly
Solution Approach 1:
The patent incorporates a buffer structure in the form of a protrusion on the cap that extends toward the electrode assembly. This protrusion acts as a cushion or barrier that prevents the laser beam from penetrating through gaps in the assembly and damaging the electrode assembly. The buffer is positioned in advance to cover potential gap areas, allowing fast assembly without compromising welding safety.
Solution Approach 2:
The protrusion on the cap serves as an intermediary element between the laser welding process and the electrode assembly. It physically blocks the laser path in case of assembly gaps, mediating the interaction between the welding process and the sensitive internal components. This allows the use of fast laser welding while protecting the electrode assembly from potential damage.
3Productivity
If the cap and current collector plate are positioned to contact the sidewall member for triple welding, then production efficiency increases, but assembly precision requirements increase
Solution Approach 1:
The patent designs the cap and current collector plate with matching contact surfaces that create equivalent positioning conditions for both components. The protrusion on the cap and the corresponding contact area on the current collector plate are designed to engage with the sidewall member at the same radial position, creating an equipotential positioning system. This ensures that both components align correctly with the sidewall member simultaneously, facilitating triple welding without requiring excessive assembly precision.
Solution Approach 2:
The patent uses an asymmetric protrusion design on the cap that contacts the sidewall member at a specific location. This asymmetric feature provides a unique positioning reference that guides the cap into the correct orientation and position relative to the sidewall member. The current collector plate is similarly designed with asymmetric contact features, allowing both components to self-align during assembly, thereby reducing the precision requirements for the overall assembly process.
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 increases production efficiency, reduces costs, and prevents laser-induced damage to the electrode assembly by ensuring precise alignment and effective heat dispersion through the current collector plate, while maintaining strong welds and stability.
Implementation Method 1
welding the sidewall member, the cap and the current collector plate all at once may be considered, which may be performed by laser
Implementation Method 2
effective heat dispersion through the current collector plate
Data Source
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AI summary
A battery cell includes a current collector plate having an axially extending can connecting part that is press-fit within a sidewall member having a multi-stage inner circumferential surface with different inner diameters. The battery cell is manufactured by inserting a cap into an open end of the can such that an axial inner surface of the cap contacts an axially outer end surface of the can connecting part and such that an outer circumferential surface of the cap contacts the inner circumferential surface of the sidewall member. Then a laser is irradiated in the axial direction on an area of the inner circumferential surface of the sidewall member and the outer circumferential surface of the cap in contact with one another, so as to form a triple welding portion.