TR10: Liquid Battery
Donald Sadoway conceived of a novel battery that could allow cities to run on solar power at night.
Conventional battery: Ordinary batteries use at least one solid active material. In the lead-acid battery shown here, the electrodes are solid plates immersed in a liquid electrolyte. Solid materials limit the conductivity of batteries and therefore the amount of current that can flow through them. They’re also vulnerable to cracking, disintegrating, and otherwise degrading over time, which reduces their useful lifetimes.
Without a good way to store electricity on a large scale, solar power is useless at night. One promising storage option is a new kind of battery made with all-liquid active materials. Prototypes suggest that these liquid batteries will cost less than a third as much as today’s best batteries and could last significantly longer.
The battery is unlike any other. The electrodes are molten metals, and the electrolyte that conducts current between them is a molten salt. This results in an unusually resilient device that can quickly absorb large amounts of electricity. The electrodes can operate at electrical currents “tens of times higher than any [battery] that’s ever been measured,” says Donald Sadoway, a materials chemistry professor at MIT and one of the battery’s inventors. What’s more, the materials are cheap, and the design allows for simple manufacturing.
The first prototype consists of a container surrounded by insulating material. The researchers add molten raw materials: antimony on the bottom, an electrolyte such as sodium sulfide in the middle, and magnesium at the top. Since each material has a different density, they naturally remain in distinct layers, which simplifies manufacturing. The container doubles as a current collector, delivering electrons from a power supply, such as solar panels, or carrying them away to the electrical grid to supply electricity to homes and businesses.