Lithium batteries may hold the key to an environmentally sustainable, oil-independent future. From electric cars to a "smart" power grid that can actually store electricity, letting us harness the powers of the sun and the wind and use them when we need them, lithium—a metal half as dense as water, found primarily in some of the most uninhabitable places on earth—has the potential to set us on a path toward a low-carbon energy economy. In , Seth Fletcher takes us on a fascinating journey, from the salt flats of Bolivia to the labs of MIT and Stanford, from the turmoil at GM to cutting-edge lithium-ion battery start-ups, introducing us to the key players and ideas in an industry with the power to reshape the world. Lithium is the thread that ties together many crucial stories of our time: the environmental movement; the American auto industry, staking its revival on the electrification of cars and trucks; the struggle between first-world countries in need of natural resources and the impoverished countries where those resources are found; and the overwhelming popularity of the portable, Internet-connected gadgets that are changing the way we communicate. With nearly limitless possibilities, the promise of lithium offers new hope to a foundering American economy desperately searching for a green-tech boom to revive it.