The battery cells produced at the Gigafactory are the new form factor '2170', jointly designed and engineered by Tesla and Panasonic.
They are larger than the 18650 cells used in the Model S and Model X automobiles.
While the cells were originally expected to be at least 20 mm in diameter and 70 mm in length, revised specifications for the optimized form factor are 21 mm (0.83 in) by 70 mm (2.8 in).
Tesla thus refers to it as the '21–70' or '2170' whereas Samsung refer to the size as '21700'.

Panasonic was expected to begin cell production in 2016, and continue for at least 10 years.
Among the machines spotted at the opening in July 2016 were presses and rollers for cathodes.
Gigafactory began mass production of 21700 cells in January 2017.
Only Panasonic cells are to be used in the US-made Model 3, and Tesla uses 21-70 format for Model 3 and Powerwall/Powerpack.
Panasonic owns some of the cell production equipment in an area not accessible to others.
By December 2018, Panasonic operated 11 cell production lines.
Some of the lines were temporarily converted from storage (NMC) to vehicle (NCA) to increase supply for the Model 3.

Tesla uses Nickel Manganese Cobalt (NMC) lithium cells for stationary storage (Powerwall and Powerpack), and Nickel Cobalt Aluminium Oxide (NCA) for vehicles.

The cell components are then encased in aluminum cans made by Heitkamp & Thumann inside GF1, using 10,000 tons per year.

An April 2019 report quoting former and current employees at Panasonic's side of the Gigafactory described how half a million of battery cells per day were scrapped because of production defects related to carelessness, lack of respect for operating procedures, and the overall pressure to increase output.
Panasonic delivered three million battery cells daily to Tesla in 2018.

At the end of 2019, Panasonic had 3000 US workers and 200 Japanese technicians at Gigafactory 1, quality had improved to increase production to a rate of 30 GWh/year on the same equipment.
Panasonic occupies more than half of the factory.
The battery cells produced at the Gigafactory are the new form factor '2170', jointly designed and engineered by Tesla and Panasonic. They are larger than the 18650 cells used in the Model S and Model X automobiles. While the cells were originally expected to be at least 20 mm in diameter and 70 mm in length, revised specifications for the optimized form factor are 21 mm (0.83 in) by 70 mm (2.8 in). Tesla thus refers to it as the '21–70' or '2170' whereas Samsung refer to the size as '21700'. 
Panasonic was expected to begin cell production in 2016, and continue for at least 10 years. Among the machines spotted at the opening in July 2016 were presses and rollers for cathodes. Gigafactory began mass production of 21700 cells in January 2017. Only Panasonic cells are to be used in the US-made Model 3, and Tesla uses 21-70 format for Model 3 and Powerwall/Powerpack. Panasonic owns some of the cell production equipment in an area not accessible to others. By December 2018, Panasonic operated 11 cell production lines. Some of the lines were temporarily converted from storage (NMC) to vehicle (NCA) to increase supply for the Model 3.
Tesla uses Nickel Manganese Cobalt (NMC) lithium cells for stationary storage (Powerwall and Powerpack), and Nickel Cobalt Aluminium Oxide (NCA) for vehicles.
The cell components are then encased in aluminum cans made by Heitkamp & Thumann inside GF1, using 10,000 tons per year.
An April 2019 report quoting former and current employees at Panasonic's side of the Gigafactory described how half a million of battery cells per day were scrapped because of production defects related to carelessness, lack of respect for operating procedures, and the overall pressure to increase output. Panasonic delivered three million battery cells daily to Tesla in 2018.
At the end of 2019, Panasonic had 3000 US workers and 200 Japanese technicians at Gigafactory 1, quality had improved to increase production to a rate of 30 GWh/year on the same equipment. Panasonic occupies more than half of the factory.
Giga Nevada