Bent Current Collection Tab for Secondary Battery Space Utilization
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Solution Overview
Problem
Secondary batteries face challenges in maximizing the utilization of internal case space and improving energy density, particularly in pouch-type batteries where the current collection tabs do not efficiently utilize the available space, leading to suboptimal energy storage capacity per unit area.
Innovation Solution
The design involves bending the current collection tab multiple times to accommodate it within the battery case, with specific bending patterns and points to optimize space usage, allowing the electrode lead to be securely connected and drawn out, thereby increasing the energy density by maximizing the internal space utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the current collection tab is kept straight and simple, then the manufacturing process is simple, but the internal space utilization of the case is low
Solution Approach 1:
The current collection tab is transformed from a straight linear structure into a three-dimensional bent structure by folding it at specific points. This dimensional transformation allows the tab to occupy vertical and lateral space within the case, converting unused void space into functional space that accommodates the tab while maintaining manufacturing simplicity through standardized bending angles (90 or 180 degrees).
Solution Approach 2:
The bent current collection tab is nested within the internal cavity of the battery case, fitting into the available space between the electrode assembly and the case walls. This nesting arrangement allows the tab to be contained within the case volume without protruding externally, maximizing space utilization while keeping the overall battery dimensions compact.
2Volume of moving object
If the current collection tab is bent multiple times to fit space, then the internal space utilization increases, but the device complexity increases
Solution Approach 1:
The current collection tab is segmented into distinct functional zones: the electrode uncoated portion, the bent intermediate sections, and the terminal end portion. Each segment serves a specific purpose - the uncoated portion connects to the electrode, the bent sections navigate around obstacles and fit within the case, and the terminal portion connects to the electrode lead. This segmentation allows for standardized bending angles and predictable assembly, reducing overall complexity despite multiple bends.
3Volume of moving object
If the length of the current collection tab is increased to twice the thickness of the electrode assembly, then the space utilization improves, but the risk of damage during lead welding increases
Solution Approach 1:
The current collection tab is designed with sufficient length (twice the electrode assembly thickness) and appropriate bending geometry to provide a cushioning effect during the lead welding process. The bent structure absorbs mechanical stress and prevents direct transmission of welding forces to the fragile connection points, thereby protecting the electrical connection from damage while maintaining the required tab dimensions for optimal space utilization.
Data Source
AI summary
A secondary battery includes an electrode assembly including a current collection tab protruding to one side; a case including a main body having an accommodating part accommodating the electrode assembly, and a cover covering the main body; and an electrode lead electrically connected to the current collection tab and drawn out of the case, wherein the current collection tab is bent twice, and a length of the current collection tab is twice a thickness of the electrode assembly.