Worth pointing out that with LFP batteries, it's actually zero percent. There are a few more cobalt free battery chemistries. But this is so far the most popular one with a rapidly growing market share that is closing in on 40% of the market. Lots of Teslas and other vehicles use them. There are a few more cobalt free battery chemistries of course. Sodium ion is getting some usage in China lately and does not involve cobalt, for example. And some of the solid state batteries don't use it either.
Cobalt isn't actually controversial because it's rare but because the way some of it is mined in Congo (i.e. with children). Most of it is actually fine and mined in a more humane way. Using children is not a hard requirement. And as the article points out recycling it is pretty doable too. And it's not all that rare either. It's by no means a rare earth.
And never mind about the other things children mine. Like copper, coal, diamonds, gold, etc. Or the fact that a lot of cobalt is also used in other industries. Like the oil refining industry, for example. Cobalt is somehow only controversial in the context of batteries. Any other form of cobalt usage is apparently not worth reporting on, scrutinizing, etc.
A lot of crocodile tears get shed over the poor children in the Congo. But only when it concerns batteries for EVs. I wonder why that is (rhetorical question with some obvious answers, I know) and whether those people actually really care. Because they sure are being awfully selective with their outrage.