Liquid Battery
Recently, researchers from MIT have designed a new kind of battery that, unlike conventional batteries, is made of all-liquid active materials. Donald Sadoway, a materials chemistry professor at MIT, and his team have fabricated prototypes of the liquid battery, and have demonstrated that the materials can quickly absorb large amounts of electricity, as required for solar energy storage.

A conventional battery consists of two solid metal electrodes immersed in an electrolyte that is touching them both. As they react over time, electrons travel through the electrolyte as well as through the load. This battery uses liquid electrodes instead. Three liquids are poured into a vessel molten magnesium, molten antimony and an electrolyte. Due to their different densities, the three liquids naturally separate; the antimony settles to the bottom, the electrolyte rests in between and the magnesium sits on top.

In the researchers' first prototype, the electrodes were molten metals - magnesium on the top and antimony on the bottom - while the electrolyte was a molten salt such as sodium sulfide. In later prototypes, the researchers investigated using other materials for improved performance.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.

As the battery discharges, the molten metals react and slowly ionize, dissolving into the electrolyte solution. Thus, when discharged, the battery is mostly electrolyte, with only thin layers of metal remaining. When it is recharged, the magnesium ions are reduced and the antimony ions are oxidized which, in this case, causes both the magnesium and antimony to go from ionic to metallic form. Thus, the recharged battery once again has thick liquid metal layers and a thin electrolyte layer.

This might not be more than an interesting chemistry experiment, were it not for the fact that such a liquid battery offers numerous advantages over conventional ones. The liquid metals and molten salt (used as the electrolyte) can absorb very high electrical currents ten times higher than the best batteries we have today, according to the MIT professor heading the project.

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