Cylindrical Battery Collector Structure for Low-Resistance Tab Welding
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Solution Overview
Problem
Cylindrical secondary batteries face high self-resistance due to limited current paths and are prone to damage at welded portions under vibration and impact, particularly in applications requiring high output and capacity like electric vehicles.
Innovation Solution
A collector structure with a bridge and tab coupling parts that gradually change width, alternately disposed, and a cover member made of insulating material, along with a beading part configuration to reduce resistance and minimize damage risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of tabs connecting the jelly-roll to the external terminal is increased, then the current path is improved and resistance is reduced, but the device complexity increases
Solution Approach 1:
The collector is divided into multiple segments (first collector and second collector) that are positioned at different locations. The first collector connects to the positive electrode tab and the second collector connects to the negative electrode tab, creating multiple parallel current paths without requiring excessive tabs from a single location. This segmentation approach distributes the current collection function across multiple strategic points.
Solution Approach 2:
The invention transitions from a single-plane tab arrangement to a three-dimensional collector configuration. The collectors extend in the radial direction and are positioned at different axial locations, creating current paths that utilize multiple spatial dimensions. This dimensional expansion allows for optimized current distribution without simply adding more tabs in the same plane.
2Ease of manufacture
If a traditional welded structure is used, then the manufacturing process is simple, but the welded portion is prone to damage under vibration and impact
Solution Approach 1:
The collector utilizes a flexible foil structure that can deform elastically under external impact or vibration. This flexible design allows the collector to absorb mechanical stress without transmitting excessive force to the welded portions, thereby protecting the welds from damage while maintaining electrical connectivity. The foil's inherent flexibility serves as a mechanical buffer against environmental stresses.
3Ease of manufacture
If the collector structure is simplified, then the manufacturing is easier, but the resistance cannot be reduced to the desired level
Solution Approach 1:
The collector design implements local quality optimization by varying the width of the collector at different locations. The first collector has a width that gradually increases from the positive electrode side toward the center, while the second collector has a width that gradually increases from the negative electrode side toward the center. This non-uniform width distribution optimizes current density distribution and reduces resistance in critical areas without requiring a completely complex overall structure.
Data Source
AI summary
A cylindrical secondary battery includes an electrode assembly provided with an electrode tab; a battery can configured to accommodate the electrode assembly; a terminal configured to pass through the battery can and insulated from the battery can; and a collector configured to electrically connect the electrode tab to the terminal. The collector may include an edge part; a terminal coupling part disposed inside the edge part and coupled to the terminal; a bridge configured to connect the edge part to the terminal coupling part; and a tab coupling part extending inward from the edge part, spaced apart from the bridge and the terminal coupling part, and coupled to the electrode tab. The bridge includes a hole defined in a central portion of the bridge in a width direction of the bridge.