It's expensive for metal parts because it's a pita to fabricate.

In batteries, it'll be a miniscule amount used and instead of a chunk of titanium, a chemical mix that includes titanium.

Otherwise, titanium, like aluminium, are rather common (like the 8 or 9th most common element on earth).

EDIT: reading the details, it's not just titanium, it's niobium-titanium oxide.

And niobium isn't quite as common as titanium (it's less common than lithium and cobalt) and is in high demand for quite a few industrial applications.

So dunno if this is actually an improvement other than that niobium being mined in Brazil and Canada instead of the hell conditions in central Africa.