Battery Cell Tab Assembly With Separated Welding Zones
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Solution Overview
Problem
The existing welding process for battery cell electrode tabs results in work-hardening, leading to poor adhesion and mechanical properties, causing weak connections between tabs and current collectors, which affects the battery's performance and lifespan due to increased electrical resistance and heat generation.
Innovation Solution
A battery cell design with dispersed welding zones along the length of flexible electrode tabs, allowing for separate welding of tabs to each other and then to current collectors without overlap, maintaining flexibility and preventing mechanical damage, using ultrasonic vibration welding for secure connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the plurality of electrode tabs of same polarity are welded together in a first welding step, then the tabs are connected to form a bundle, but the tabs undergo work-hardening which degrades their mechanical and structural properties
Solution Approach 1:
The patent divides the welding process into two distinct spatial zones: a first welding zone where tabs are welded to each other, and a second welding zone where the tab bundle is welded to the current collector. This segmentation prevents work-hardening from affecting the entire tab structure, preserving mechanical properties while achieving secure connections.
Solution Approach 2:
The patent applies welding locally in specific zones rather than uniformly across all tabs. The first welding zone is positioned at a first location on the tabs, while the second welding zone is positioned at a second location, ensuring that work-hardening is confined to localized areas and does not compromise overall tab strength.
2Ease of manufacture
If the pre-welded bundle of tabs is welded to the current collector in the same zone, then the connection is formed, but the adhesion is poor due to work-hardening degradation
Solution Approach 1:
The patent segments the welding locations into two distinct zones: the first welding zone for tab-to-tab welding and the second welding zone for tab-bundle to current collector welding. This spatial separation ensures that the welding area for the current collector connection is not degraded by work-hardening from the first welding step, thereby improving adhesion and connection reliability.
3Length of moving object
If the welding zones are dispersed along the width dimension of the electrode tabs, then the length dimension of the tabs can be kept small, but the layout complexity increases
Solution Approach 1:
The patent transitions from a single-zone welding approach to a multi-zone approach dispersed along the width dimension of the tabs. By utilizing the width dimension for zone dispersion, the patent reduces the required length dimension of the tabs while maintaining connection effectiveness, effectively using an additional spatial dimension to resolve the contradiction.
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 ensures a secure, compact, and reliable mechanical and electrical connection between electrode tabs and current collectors, enhancing the battery cell's performance and lifespan by maintaining tab flexibility and preventing mechanical damage during assembly.
Implementation Method 1
using ultrasonic vibration welding for secure connections
Implementation Method 2
The first multi-layered bundle of flexible electrode tabs is welded to the first current collector in a second welding zone
Data Source
Figure 1
Figure 2
AI summary
A battery cell comprises at least a first current collector (32) and a stack of electrodes (12) provided with a first multi-layered bundle (24) of flexible electrode tabs (16) protruding from a side (18) of said stack of electrodes (12). The flexible electrode tabs (16) are welded to one another, but not to the first current collector (32), in at least one first welding zone (26) of the first multi-layered bundle (24) of flexible electrode tabs. The first multi-layered bundle (24) of flexible electrode tabs is welded to the first current collector (32) in a second welding zone (36) of the first multi-layered bundle (24) of flexible electrode tabs. The second welding zone (36) and the first welding zone (26) do not overlap and are positioned next to each other or spaced apart in a direction parallel to a width dimension (W) of the flexible electrode tabs (16).