Meaning
Mechanical degradation processes affect the delicate electrical connections within a battery cell due to repeated stress from thermal expansion or vibration. Tab weld fatigue occurs when the ultrasonic or laser welds that connect the electrode foils to the external terminal tabs weaken and crack. This failure increases the internal resistance of the cell and can eventually cause a complete loss of electrical contact.
Engineering teams evaluate the mechanical durability of these joints to ensure long-term reliability under operating conditions.
Thermal Cycling
As the cell heats and cools during charge cycles, the different materials expand and contract at different rates. This differential expansion exerts continuous shear stress on the weld joints. Over time, these thermal cycles can lead to micro-cracking and electrical failure.
Testing Evaluation
Engineers subject weld samples to pull tests and fatigue simulations to measure their resistance to mechanical failure. This testing ensures that the welding process parameters are optimized for production. Sourcing managers use these test results to verify the durability of the cells.
Failure Consequence
A fractured weld tab can cause intermittent power loss or localized electrical arcing inside the cell. This arcing can trigger thermal runaway and destroy the battery pack. Ensuring weld integrity is essential for the safety of high-voltage systems.
