Battery Cell End Cap Structure for Laser Weld Stress Relief
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Solution Overview
Problem
Existing battery cells face safety issues due to the risk of laser beam burning other members during welding and the inability to effectively release welding stress, leading to deformation and cracking of the welding region, which compromises sealing performance.
Innovation Solution
The battery cell design incorporates a protruding portion on the end cap to block the laser beam during welding and a recessed portion to release welding stress, ensuring the cap body and housing are securely connected while reducing the risk of deformation and improving sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is used to connect the cap body and housing, then welding strength and sealing performance are improved, but the risk of laser beam burning other members increases
Solution Approach 1:
A laser beam receiving member (protruding portion) is introduced as an intermediary element between the laser beam path and the electrode assembly. This member intercepts and blocks the laser beam, preventing it from reaching and burning the electrode assembly, while still allowing the welding process to proceed effectively
2Strength
If the cap body is rigidly structured to ensure welding strength, then connection strength is improved, but welding stress release capability deteriorates
Solution Approach 1:
The cap body is segmented into multiple functional regions: a rigid cap body portion for maintaining structural strength and a protruding portion with a recessed part for stress release. This segmentation allows different regions to serve different functions - the main body provides strength while the protruding portion with its recessed structure enables welding stress release through controlled deformation
3Object-affected harmful factors
If the protruding portion is made thicker to block laser beam effectively, then laser beam blocking capability is improved, but welding stress release capability deteriorates
Solution Approach 1:
The protruding portion features a recessed part that creates local quality variation - the wall thickness is reduced at the recessed region compared to other parts of the protruding portion. This local thinning allows the recessed part to deform more easily for stress release, while the thicker portions of the protruding portion maintain effective laser beam blocking capability
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
The design effectively blocks laser beam exposure to other components, reduces welding stress, and enhances sealing performance by preventing deformation and cracking, thereby improving the safety and structural integrity of the battery cell.
Implementation Method 1
The protruding portion protrudes from an inner surface of the cap body toward the electrode assembly, and is configured to block a laser beam during welding between the cap body and the housing
Implementation Method 2
A first recessed portion or recess is formed on the end cap at a position corresponding to the protruding portion, and is recessed from an outer surface of the cap body toward the electrode assembly. The first recessed portion is configured to release a stress during welding between the cap body and the housing
Implementation Method 3
at least a part of the cap body is disposed around the protruding portion and configured to be laser-welded to the housing
Data Source
AI summary
A battery cell may include: a housing having an opening; an electrode assembly, accommodated in the housing; and an end cap, including a cap body and a protruding structure, where at least a part of the cap body may be disposed around the protruding structure and laser-welded to the housing so that the end cap fits and covers the opening. In a thickness direction of the end cap, the protruding structure may protrude from an inner surface of the cap body toward the electrode assembly, and block a laser beam during welding between the cap body and the housing. A first recess may be formed on the end cap at a position corresponding to the protruding structure, and recessed from an outer surface of the cap body toward the electrode assembly.