Tab welding in battery manufacturing is the process of attaching metal tabs to the current collectors of electrodes so they can be connected to the external terminals of the cell. These tabs are typically thin strips of metal, like nickel, aluminum, or copper, depending on the cell design. Tabs protrude from the cell to allow for electrical connection to the outside of the cell. Welding is used to ensure a low-resistance, robust connection that can carry high current without heating. Common welding methods include ultrasonic, resistance spot welding and laser. Good tab welds are crucial for safety (a bad weld can heat up or fail under high current) and performance (a resistive weld wastes energy and can cause imbalance among cells).
NOVONIX’s uses all of the above types of welding in their pilot line for cell prototyping. When they assemble pouch cells, they must weld the electrode foil stacks to the tabs with ultrasonic welding. They must optimize the welding parameters so as not to damage the electrodes but still get a strong bond. If they are testing a new current collector or tab material (say, a thinner foil or a different metal), they will need to adjust welding settings to ensure good weld quality. For wound jellyrolls, tabs are ultrasonically welded to the electrode foils. For cylindrical cells, the anode tab is welded to the can using resistance welding and the cathode tab is welded to the header with a laser weld. NOVONIX ensures that their prototype cells have reliable tab welds so the data reflects the chemistry, not a hardware flaw.
