Nigeria, July 8 -- Abdulsalam Musa squats as he chips away at lithium-rich rocks with a chisel and hammer in a mining pit in Nigeria's northwestern state of Kaduna.

The work is dangerous and backbreaking and the 19-year-old is covered in sweat, but he will earn about N4,000 ($2.50) for the day - enough to cover his food costs.

"Sometimes, the pits collapse and if someone is trapped inside, that's his end," said Mr Musa, resting his back on the edge of the 250-metre-deep hole he had just been mining.

Lithium is a key ingredient of rechargeable batteries for electric vehicles (EVs) and energy storage that are critical for the clean energy transition. The surging global demand for the light and silvery metal has opened a new mining fronti...