Embossed Electrode Tab Structure for Ultrasonic Welding
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Solution Overview
Problem
Conventional secondary battery jelly rolls face issues with electrode tab wear and reduced weldability during ultrasonic welding due to flat tabs, leading to potential separation of active materials and decreased productivity and safety.
Innovation Solution
The introduction of an embossed structure on electrode tabs protruding towards uncoated portions enhances friction and weldability, using ultrasonic welding with horn tips that correspond to the embossed structure, reducing wear and improving connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flat electrode tabs are used for ultrasonic welding, then the welding process is simple, but the electrode tabs wear down and weldability decreases
Solution Approach 1:
The electrode tab is designed with a curved surface instead of a flat surface. The convex curved surface contacts the uncoated portion of the electrode sheet during ultrasonic welding, distributing the welding pressure and friction more evenly across the contact area. This curvature prevents localized wear and maintains weldability over multiple welding operations.
Solution Approach 2:
The electrode tab features a localized convex curved surface at the welding contact area, while the rest of the tab maintains its original flat structure. This localized modification concentrates the wear resistance and improved weldability properties exactly where needed (at the contact point with the electrode sheet) without adding unnecessary complexity elsewhere in the tab structure.
2Strength
If flat electrode tabs are used, then manufacturing is simple, but friction during welding is insufficient leading to tab wear
Solution Approach 1:
The convex curved surface on the electrode tab increases the contact area and friction between the tab and the uncoated portion of the electrode sheet during welding. This enhanced friction prevents relative movement and wear, ensuring strong mechanical bonding and electrical connection strength.
Solution Approach 2:
The curved surface geometry works synergistically with ultrasonic vibration during the welding process. The vibration, combined with the curved contact surface, generates increased friction and heat at the interface, improving weld penetration and bond strength while preventing tab wear.
3Productivity
If conventional flat tabs are used, then welding process is straightforward, but productivity decreases due to tab wear and rework
Solution Approach 1:
The convex curved surface is pre-formed on the electrode tab during tab fabrication, before the welding process. This preliminary geometric modification ensures that when welding occurs, the optimal contact geometry is already in place, preventing wear and eliminating the need for rework or replacement of worn tabs, thus improving overall productivity.
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
The embossed structure improves weldability and safety by minimizing electrode tab wear and ensuring strong connections between tabs and sheets, enhancing the productivity and reliability of secondary battery cells.
Implementation Method 1
The introduction of an embossed structure on electrode tabs protruding towards uncoated portions enhances friction and weldability
Implementation Method 2
electrode tabs are connected to uncoated portions of the electrode sheets by welding
Data Source
AI summary
Disclosed herein is a jelly roll for a secondary battery configured by winding a cathode sheet, a separator, and an anode sheet, wherein electrode tabs are connected to uncoated portions of the electrode sheets, to which electrode active materials are not applied, by welding, and each of the electrode tabs is configured to have an embossed structure protruding toward the uncoated portion to improve weldability.