Berkeley Lab researcher Elton Cairns has developed a technology that addresses limitations of developing a commercial-grade lithium/sulfur battery. The Berkeley Lab technology uses nanostructured sulfur particles for the positive electrode. These tiny particles are designed to block migration of polysulfides that would otherwise migrate into the electrolyte and bind (as Li2S) to electrode surfaces, sharply degrading performance and shortening battery life. Coin-sized lithium/sulfur cells made with these sulfur nanoparticles are lightweight, long-lasting and have a high specific energy.
The Berkeley Lab technology uses lithium as the material for the negative electrode. Negative electrodes made from butter-like lithium have a theoretical specific capacity that is roughly eight times higher than that of graphite, which is used in most Li-ion cells sold today. The electrolyte is compatible with lithium metal electrodes.
Most commercial lithium-ion batteries feature electrodes made of cobalt oxide and other transition-metal oxides, plus carbon. But cobalt oxide is expensive, potentially toxic and unsafe (fire hazard). Research into more practical lithium ion batteries typically centers on the reduced use or elimination of cobalt to lower costs and improve safety.
This lithium/sulfur technology is a promising route to batteries that could expand the range of electric and plug-in hybrid vehicles to at least 300 miles from the current 100 miles between charges. With Earth-abundant sulfur as its primary material, efficient lithium/sulfur electrodes are low-cost, non-toxic and do not present the environmental and recycling challenges of batteries containing cobalt. Because sulfur is less flammable than other elements, these batteries also address mounting safety concerns surrounding the use of lithium batteries in aircraft, automobiles, tools and consumer electronics.
