Cobalt

Your Smartphone was Probably Made With Child Labor

Lithium ion batteries are becoming more and more common in today’s consumer electronics and electric vehicles. One of the main materials used in the production of lithium ion batteries is cobalt, the majority of which comes form the Democratic Republic of the Congo. This article delves in depth with some of the humanitarian issues involved with the production of lithium ion batteries.

http://fortune.com/longform/blood-sweat-and-batteries/