The batteries in the Model 3 are not in fact off-the-shelf Panasonic batteries.
Tesla has the largest single battery factory, but they seem to be second behind CATL in the latest annualized production rates.
CATL shipped 7.3GWh in 2018-Q2, I can’t find Q3 numbers but I did find one site saying “monthly installed battery capacity with 1.47GWh, 2.45GWh, 2.49GWh and 3.4GWh produced respectively from August to November in 2018.” But these are not just EV batteries.
For EV batteries specifically, Tesla produces more than 50% of global supply.
The global lead-acid battery market is still much larger than the global li-ion market, so your statement that Tesla is the world's largest battery maker has degraded into Tesla is the world's 2nd-largest maker of Li-ion batteries for the EV market, a much weaker statement.
Tesla claims they make 60% of all supply for the EV market specifically.
I believe this excludes plug-in hybrids and buses. It is also counting all Gigafactory pack capacity, which includes cells made by Pano in Asia that are assembled at Giga for Model S/X packs, so a bit squishy.
Tesla has the largest single battery factory, but they seem to be second behind CATL in the latest annualized production rates.
CATL shipped 7.3GWh in 2018-Q2, I can’t find Q3 numbers but I did find one site saying “monthly installed battery capacity with 1.47GWh, 2.45GWh, 2.49GWh and 3.4GWh produced respectively from August to November in 2018.” But these are not just EV batteries.
For EV batteries specifically, Tesla produces more than 50% of global supply.