Tesla's 4680: laser-etched 'tabless' foils made a bigger cell run cooler, not hotter

At Battery Day on 22 September 2020, Elon Musk and Drew Baglino unveiled the 4680: a cylindrical cell 46 mm wide and 80 mm tall, roughly six times the volume of the Panasonic 2170 cells then powering Teslas, to be manufactured in-house. The point of going big is packaging: Shirley Meng of UC San Diego noted that large formats cut the inactive material around each cell, so pack-level energy density rises and cost falls. Tesla claimed the new design would cut cost per kilowatt-hour by 56 percent.

The catch is the tab. In every EV cell, thin copper and aluminium collector foils carry current out through small welded tabs, and those tabs hobble the cell: they consume coated area, require specialized ultrasonic welds, and concentrate all the current through one spot, which grows worse as the cell grows. The conventional fixes — more tabs, bigger welds, or simply not making cells bigger — each add cost or leave the constraint intact.

Tesla's answer was to have no tab at all. Baglino described laser-patterning the collector foils so they hold dozens of connections to the electrode — the 'shingled spiral' printed on the Battery Day T-shirts. 'The distance the electron has to travel is much less,' Musk said: even though the cell is bigger, it has a better power-to-weight ratio. Greg Less, who runs the University of Michigan's Battery Lab, confirmed the logic — taking tabs out frees more coated area, raising capacity without changing anything else.

Laser-cut the foils so the whole edge becomes the tab

Resistance grows with current path length; spreading collection across the whole electrode edge collapses that path no matter how wide the can gets.

Tabs waste coated area and demand a precision weld on every foil; removing them deletes a slow, failure-prone step from the assembly line.

Bigger cells mean fewer cells per pack — fewer casings, welds and bus connections, which is where the cost and inactive mass actually live.

The trick is pure geometry: the cell's power-to-weight ratio improves while chemistry, coatings and suppliers stay the same.

Find the part that stops scaling and delete it. The welded tab that served a laptop cell became the bottleneck at 46 mm; removing it turned a manufacturing constraint into a power advantage.

The ramp was slower than the pitch: Tesla fought dry-electrode bottlenecks through 2022 and 2023. By the Q1 2023 call Baglino said Tesla was producing not just the first-generation tabless cell but 'a second more manufacturable version' at Gigafactory Texas, with output up 50 percent quarter-over-quarter and unit cost down 25 percent in the quarter. The cell also unlocked the structural pack — cells as the vehicle floor — credited with 50 percent lower capital cost and a 66 percent smaller factory per GWh; the Texas Model Y shipped with it first, then the Cybertruck.