Is there such a thing as an ethical electric car?

The Democratic Republic of Congo is at the epicenter of a modern-day "gold rush" for cobalt, about a fifth of which is dug out of makeshift artisanal mines by hand. The mineral is an essential component in the rechargeable batteries powering electric vehicles and cellphones - but at what cost? CNN's findings show that the companies profiting from the clean energy revolution have a problem: They can't prove that children aren't involved in their supply chains.