Tracing the origins of the graphite in a phone, for example, requires finding out where the phonemaker obtains batteries, where the battery makers acquire the portion of batteries known as anodes, and where the anode producers get their graphite. Moreover, because there are multiple suppliers at each step and various types of graphite, it is difficult to know where any given batch of the mineral ends up.
Several companies declined to disclose the origin of their graphite. For example, Tesla, perhaps the best-known electric-car maker, uses Panasonic batteries. Tesla said those batteries have never included graphite from the Chinese company BTR, but it declined to identify its graphite source.