The latest buzzword in battery materials sounds like a concept borrowed from astrophysics.

But "black mass” is just a very literal description of the intermediate product from recycling either spent electric-vehicle batteries or scrap from battery plants. It’s a dark, powdery cocktail of metals such as lithium, cobalt and nickel that’s emerging as a commodity in its own right.

There’s growing interest in battery recycling as the global electric-vehicle industry expands, and as carmakers and Western governments aim to build supply chains that bypass China.