Battery Cell Seam Welding for Sealing and Space Utilization
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Solution Overview
Problem
The inefficiency in utilizing the internal space of cylindrical battery cans due to the need for separate welding masks or jigs during the manufacturing process, which reduces energy density per unit volume and increases production costs and complexity.
Innovation Solution
A welding structure that integrates the process of welding the collector plate to the can and cap into a single seam welding process, using a triple weld portion and a double weld portion with controlled laser energy density and scan speed to ensure efficient sealing and electrical connection without excessive heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate welding masks or jigs are used during the manufacturing process, then reliable welding of collector plate to can and cap is achieved, but internal space utilization is reduced and energy density per unit volume decreases
Solution Approach 1:
The patent integrates the functions of separate welding masks and jigs into a unified welding structure where the can itself serves as the positioning fixture and the welding mask is eliminated. The collector plate is directly welded to the can and cap without requiring external masking or jigging devices, thereby eliminating the need for additional internal components and maximizing internal space utilization.
Solution Approach 2:
The can structure is designed to serve multiple functions: it acts as both the container and the welding fixture/positioning device. The rim of the can provides the welding surface for both the collector plate and cap, eliminating the need for separate jig structures and optimizing space usage while maintaining welding reliability.
2Reliability
If separate processes are used for welding collector plate to can and for connecting cap to sidewall member, then reliable electrical connection and sealing are achieved, but production efficiency decreases and production cost increases
Solution Approach 1:
The patent combines the welding of the collector plate to the can and the welding of the cap to the sidewall member into a single integrated welding process. The welding structure allows both connections to be established simultaneously or in sequence without requiring separate positioning and masking operations, thereby reducing the number of manufacturing steps and improving production efficiency while maintaining reliable electrical connection and sealing.
3Productivity
If welding process is optimized for speed and efficiency, then production efficiency increases, but welding heat generation may adversely affect the electrode assembly
Solution Approach 1:
The welding structure is designed to concentrate the welding heat locally at the connection points between the collector plate and can, and between the cap and sidewall member, while minimizing heat transfer to the electrode assembly. The structure allows for controlled heat input zones that prevent excessive thermal effects on the sensitive electrode components, enabling faster welding speeds without compromising electrode assembly integrity.
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 enhances energy density, reduces production costs, and simplifies the assembly process while ensuring stable and reliable welding, suitable for mass production.
Implementation Method 1
a first weld portion in which the can, the collector plate, and the cap are welded together during a seam welding process
Implementation Method 2
a second weld portion in which at least the can and the cap are welded together in the remaining seam welding section
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present disclosure provides a welding structure of a battery can, a collector plate, and a cap, a welding method, and a battery cell to which the welding structure and the welding method are applied. The battery cell includes a can and an electrode assembly accommodated inside the can. The can includes a bottom member, a sidewall member connected to the bottom member and extending in an axial direction, and a cap configured to cover an open end provided at one axial end of the sidewall member. A can connection portion is provided on an edge of a collector plate electrically connected to an electrode of the electrode assembly so as to come into electrical contact with the can. An edge of the cap is welded and fixed. The welding includes a plurality of first weld portions having an edge of the open end of the sidewall member, an edge of the cap, and the can connection portion, which are welded together, and spaced apart from each other in a circumferential direction, and a second weld portion having at least an edge of the open end of the sidewall member and an edge of the cap, which are welded, and disposed between the first weld portions. The first weld portion and the second weld portion are formed continuously to be alternately disposed along the circumferential direction.