Battery Current Collector Tab Tip Geometry and Ultrasonic Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The alignment issues of current collector tabs in battery manufacturing lead to poor bonding and lower yields due to positional variations, causing internal shorts and inhibiting other components, especially when using aluminum materials which are prone to oxidation and bursting during bonding processes.
Innovation Solution
The solution involves creating a tip portion on the current collector tabs with a narrower width perpendicular to the extending direction, allowing for better alignment and avoiding overlap with the lead joints during bonding, using ultrasonic welding for the tabs and laser or resistance welding for the leads, and incorporating a leg in the intermediate lead to reduce stress and deformation during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If current collector tabs are bonded using conventional methods (laser or resistance welding), then bonding strength may be achieved, but alignment precision deteriorates due to machine accuracy problems causing tab misalignment
Solution Approach 1:
The patent applies preliminary action by pre-aligning and fixing the current collector tabs to the lead using ultrasonic bonding before the final laser welding process. This preliminary fixation ensures that tabs remain properly positioned during subsequent operations, preventing misalignment issues that would otherwise occur due to machine accuracy limitations in the final welding step.
Solution Approach 2:
The patent introduces ultrasonic bonding as an intermediary process between tab placement and final laser welding. This intermediate step acts as a mediator that secures tabs in their correct positions, allowing the subsequent laser welding to proceed without alignment problems. The ultrasonic bonding process bridges the gap between initial tab positioning and final permanent attachment.
2Reliability
If multiple current collector tabs are bonded together, then electrical conduction is improved, but yields deteriorate due to alignment issues causing internal shorts or poor laser welding
Solution Approach 1:
The patent uses ultrasonic bonding as a preliminary action to secure multiple current collector tabs to the lead before final laser welding. This preliminary fixation ensures all tabs are properly positioned and won't interfere with each other or cause internal shorts during the welding process, thereby maintaining high yields while achieving reliable electrical conduction through multiple bonded tabs.
Solution Approach 2:
Ultrasonic bonding serves as an intermediary process that enables multiple tabs to be reliably connected without compromising manufacturing yield. By introducing this intermediate bonding step, the patent resolves the conflict between connecting multiple tabs for better conduction and maintaining high yields by preventing alignment-related defects.
3Reliability
If aluminum material is used for current collector tabs, then oxidation resistance is improved, but bonding quality deteriorates due to oxide film formation causing bursting during resistance welding
Solution Approach 1:
The patent introduces ultrasonic bonding as an intermediary process that bypasses the problems associated with resistance welding of aluminum. This intermediate bonding method doesn't suffer from the oxide film bursting issue, allowing aluminum tabs to be securely attached to the lead while maintaining their oxidation resistance properties. The ultrasonic process acts as a mediator that enables bonding without the harmful effects of conventional resistance welding on aluminum.
Solution Approach 2:
The patent replaces the thermal-based resistance welding mechanism with a mechanical vibration-based ultrasonic bonding mechanism for attaching aluminum current collector tabs. This substitution eliminates the problem of oxide film bursting that occurs during resistance welding of aluminum, while still achieving strong, reliable bonds. The mechanical ultrasonic process is better suited for bonding aluminum materials without the drawbacks of thermal welding.
4Reliability
If current collector tabs are made wider for better electrical contact, then electrical conduction is improved, but alignment tolerance deteriorates causing more overlaps with lead joints
Solution Approach 1:
The patent applies preliminary ultrasonic bonding to secure wider current collector tabs to the lead before final assembly. This preliminary action ensures that even wider tabs with reduced alignment tolerance are properly positioned and fixed, preventing overlaps with lead joints during subsequent operations. The early fixation compensates for the reduced tolerance inherent in wider tab designs.
Solution Approach 2:
Ultrasonic bonding serves as an intermediary process that enables the use of wider current collector tabs despite their reduced alignment tolerance. By introducing this intermediate bonding step, the patent allows wider tabs to be securely attached without causing overlap problems during final assembly, thus maintaining both good electrical conduction and manufacturing feasibility.
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 improves the bonding quality and yield of the battery by reducing the area occupied by the tabs, preventing overlaps, and ensuring solid connections with lower resistance values, while maintaining the reliability of the gas relief vent and preventing its degradation.
Implementation Method 1
Ultrasonic bonding is suitable to bond plural current collector tabs together, and the ultrasonic bonding is also suitable to bond plural current collector tabs to an external lead or the like connected to a battery case
Implementation Method 2
When plural current collector tabs are bonded to a lead by ultrasonic bonding, and then the lead is bonded to another lead by laser welding
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
According to one embodiment, there is provided a battery including a case (1), a lid (2), an electrode group (3), an intermediate lead (4), and a terminal lead (5). The electrode group (3) has an end face opposed to the lid (2) and includes current collector tabs (31, 32) extending from the end face. The intermediate lead (4) contains an electrode group joint and a lead joint. The terminal lead (5) is electrically connected to the lid (2) and the lead joint of the intermediate lead (4). Each of the current collector tabs (31, 32) has a tip portion whose width in the direction perpendicular to the extending direction is narrow. The tip portion thereof is electrically connected to the electrode group joint.