Tesla has held battery supply deals with Panasonic, CATL, and LG Chem, but has also started building its own cells in-house. In 2020, Tesla unveiled its 4680 battery cell, which has already been prototype-tested by Panasonic. Tesla has been building the cell at the Kato Rd. facility just a few blocks away from Fremont’s front doors. The automaker has not scaled this cell to mass production as of yet, and Tesla could always use more battery cells.