Battery makers are keen to reduce their use of costly and controversial cobalt. Half the world’s supply of the metallic element comes from the Democratic Republic of Congo, a war-torn land in which child labor is common. Worse yet, the stuff is getting expensive – cobalt prices have climbed to their highest level in a decade.

Tesla said in its recent letter to shareholders that it has slashed its use of cobalt in the Model 3’s battery cells, while raising nickel content, and that its latest batteries already require less cobalt than other battery-makers’ products. On a conference call with analysts, Musk said, “We think we can get cobalt to almost nothing.”

Tesla has been working to kick its cobalt habit “for literally several years now, and this has been extremely helpful in the overall cost per kilowatt hour, especially with recent commodity price movements,” said CTO JB Straubel.

Tesla claims in its shareholder letter that its battery cells offer the highest energy density of any on the market. “We have achieved this by significantly reducing cobalt content per battery pack while increasing nickel content and still maintaining superior thermal stability.”

Source: Bloomberg