Donald Sadoway, a materials chemistry professor at MIT, and his colleagues have developed a liquid battery that might cost less than a third as much as today’s best batteries and last significantly longer:
The molten active components (colored bands: blue, magnesium; green, electrolyte; yellow, antimony) of a new grid-scale storage battery are held in a container that delivers and collects electrical current (left). Here, the battery is ready to be charged, with positive magnesium and negative antimony ions dissolved in the electrolyte. As electric current flows into the cell (center), the magnesium ions in the electrolyte gain electrons and form magnesium metal, which joins the molten magnesium electrode. At the same time, the antimony ions give up electrons to form metal atoms at the opposite electrode. As metal forms, the electrolyte shrinks and the electrodes grow (right), an unusual property for batteries. During discharge, the process is reversed, and the metal atoms become ions again.