I was going to comment about perhaps that's because so much of it is mined in China, but a quick google says China is a rather distant third behind Australia and Chile. The more you know.
China is the leading lithium refiner. The price referenced (battery grade lithium carbonate) is an output of a refinery, not a mine. There are many different numbers thrown around for China's refining share, but they are all significant, typically all > 50%.
