[hwillis]

NiMH batteries used lanthanum, but we don't use NiMH any more. Li-ion batteries use heavy metals, specifically cobalt, of which China is the largest buyer. Almost all cobalt comes from Congo though.

Cobalt is widely available everywhere, as are rare earths. Congo just happens to have a freakishly high amount of it plus cheap everything, so it is widely mined there. Unlike other technology mining easily transfers and it doesn't take much time (a few years) or money to open new mines. This battery doesn't use cobalt at all, and most newer batteries use significantly less cobalt or none at all (LiFePO4). Phones and batteries still use a lot of cobalt, and are major consumers, but the biggest consumer is machine tools.