Cylindrical Battery Tab Cutting to Reduce Substrate Overlap Damage
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Solution Overview
Problem
In the manufacturing of cylindrical secondary batteries, substrates are prone to damage during pre-folding and compaction due to irregular bending and increased overlapping, which affects the integrity and electrical connectivity of the electrode assembly.
Innovation Solution
The substrates are cut with a varying cutting width and depth, ranging from 100% to 150% of the forming position, with a cutting direction that forms an acute angle or oblique line, to minimize overlapping and facilitate smooth folding and compaction, thereby preventing damage and ensuring proper electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrates are compacted before connection to current collector plate, then electrical connectivity is improved, but substrate damage increases due to irregular bending and folding
Solution Approach 1:
The substrate is pre-cut with a cutting depth of 100% to 150% relative to the forming position before compaction. This preliminary cutting action creates a folded structure that guides the substrate during subsequent compaction, preventing irregular bending and damage while maintaining electrical connectivity.
Solution Approach 2:
The cutting depth varies locally across the substrate - deeper cuts (100%-150% of forming position) are made at critical folding locations to create hinge-like structures, while other areas remain intact. This localized modification allows controlled folding without compromising overall substrate strength.
2Ease of manufacture
If substrates are cut to form tabs before winding, then connection to current collector plate is facilitated, but overlapping amount increases toward winding center causing severe substrate damage
Solution Approach 1:
The cutting depth parameter is optimized to 100%-150% of the forming position, which creates an optimal balance between tab formation and damage prevention. This specific parameter range allows the substrate to fold cleanly without excessive overlapping that would cause damage at the winding center.
Solution Approach 2:
The substrate is pre-cut with the optimized cutting depth before the winding process begins. This preliminary action ensures that when the substrate is subsequently wound, the pre-formed folds guide the material flow and prevent excessive overlapping, thereby protecting the substrate from damage.
Data Source
AI summary
A secondary battery includes an electrode assembly which is wound and includes a first electrode plate including a first uncoated portion, a second electrode plate including a second uncoated portion, and a separator between the first electrode plate and the second electrode plate, a case having a cylindrical shape and accommodating the electrode assembly, and a cap assembly sealing the case, and a cutting depth before winding of each of the first uncoated portion and the second uncoated portion is in a range of 100% to 150% as compared with a forming position. When a non-coated portion for forming a substrate tab is cut, a cutting width is changed to increase toward a winding end, thereby minimizing or reducing an overlapping amount between substrates during winding, and damage to the substrate during pre-folding or compaction of the substrate may be prevented or substantially prevented.