Not sure how anyone can have a Mature battery recycling system when car batteries at any scale in general are less then 5 years old.

I would suspect the companies doing battery recycling are less then 3 years old, not mature by any measurement.

BYD was founded in 1995 as a battery manufacturing company. If you have doubts about their scalability then I suggest you look at their vehicles sales year by year. Scaling does not seem to be a problem they have.