Liquid metal batteries: Past, present, and future

The evolution of the liquid metal battery is a story of a novel technology originally conceived in a different economic and political climate to provide flexibility in addressing the constraints of a society just entering the nuclear age and with aspirations to electrify the everyday experience. Ironically, it is these same massive research projects that receded into obscurity that can now be resurrected and reinvented as an exciting opportunity for addressing society's ambitions for both sustainable and environmentally benign energy. Building upon those early advances in classical electrometallurgy, four decades later the US government began to fund pioneering work at a few of the nation's top industrial and national laboratories to develop allliquid cells for energy storage applications. Motivated by the Cold War battle for technological supremacy, intensive research on these thermally and electrically rechargeable all-liquid energy storage cells continued in the US throughout the next decade, only to be abandoned as efforts shifted toward higher-energy-density rechargeable cells with immobilized components better suited for automotive applications.