KOLWEZI, Democratic Republic of Congo—Miners push bicycles piled high with bags of a grayish-blue ore along a dusty road to a makeshift market. There, they line up at wholesalers with nicknames such as Crazy Jack and Boss Lee.

Most of the buyers are Chinese. Those buyers then sell to Chinese companies that ship the bags, filled with cobalt, to China for processing into rechargeable, lithium-ion batteries that power laptops and smartphones and electric cars.

There is a world-wide race to lock up the supply chain for cobalt, which will likely be in even greater demand as electric-car production rises. So far, China is way ahead.

Chinese imports of cobalt from Congo, the world’s biggest producer of cobalt, totaled $1.2 billion in the first nine months of 2017, compared with just $3.2 million by India, the second-largest importer, government data show.

“We’re realizing that the Congo is to [electric vehicles] what Saudi Arabia is to the internal combustion engine,” says Trent Mell, chief executive of exploration company First Cobalt Corp., based in Toronto. Chinese firms are keenly aware of Congo’s importance to electric vehicles, he says, and “trying to control the whole ecosystem…from cobalt mining to battery production.”