For the record, Tesla’s gigafactory in the US state of Nevada officially began making 2170 lithium-ion battery cells for its Powerwall 2 and Powerpack 2 energy storage systems on January 4, the firm said.

The new cell — with dimensions of 21mm by 70mm, hence 2170 — is thicker and taller than the previous 18650 standard cell format.

Tesla CEO Elon Musk has been boasting about the new cell for months. “It’s the highest energy density cell in the world and also the cheapest,” he said.

“We’ve flipped the switch on cell production at the Gigafactory,” Tesla posted on its Facebook page, alongside a video showing the battery cells, which were jointly designed by Tesla and Panasonic, on the factory production line.

The much-anticipated cell for the Tesla Model 3 car will begin production in the second quarter of 2017, and by 2018 the site should produce 35 GWh/year of lithium cells.

Tesla broke ground for the gigafactory in 2014 and the present 1.9 million square feet area is just a third of the anticipated final size, which will make it the biggest building in the world, Tesla claims.