Tesla used jap batteries but their performance have been surpassed by new ones from China.
Currently BMW testing US made solid state batteries said to have higher power storage capacity but it's still a long way off before it gets mass manufactured. By then, china batteries would have caught up or match it's performance at a lower price.
The china manufacturing juggernaut are constantly upgrading and improving at a speed we have not experienced. Even current car EV models are being upgraded from within to make it current. If it's seen as old tech, it won't sell In China market.