African Mining October 2019 | Page 41

MINING IN FOCUS  T he development of next-generation rechargeable batteries that store more energy and last longer has been stifled by an electrochemical challenge. Australian engineering company, Cornell engineers, has come up with a simple but clever solution to the problem. Lithium-ion batteries, like those used in cellphones and electric vehicles, are limited in their electric-charge capacity because of their graphite anodes. Researchers have sought anodes made from alkali metals such as lithium and sodium because they allow for greater capacity, but alkali metals are highly reactive with traditional battery electrolytes. This can lead to the formation of dendrites – pointy metallic structures that make the battery susceptible to a shorter lifetime and potentially dangerous short-circuiting. Tin as an interface A team of engineers working in the lab of Lynden Archer, professor of chemical and biomolecular engineering, and director of the Cornell Energy Systems Institute, has demonstrated a cost-effective way to stabilise lithium and sodium anodes using tin as a protective interface between the anode and the battery’s electrolytes. "Lots of effort has been devoted to developing sodium- ion batteries because sodium is cheaper than lithium. The research is detailed in a paper titled, ‘Fast ion transport at solid-solid interfaces in hybrid battery anodes’, published in Nature Energy in March this year. By dropping tin into a battery’s carbonate-based electrolyte, the research team found that an artificial interface instantly forms on the alkali-metal anode, creating a nanometer-thick barrier that protects the anode like a shield, while keeping it electrochemically active. www. africanmining.co.za African Mining Publication African Mining African Mining  October 2019  39