African Mining October 2019 | Page 42

 MINING IN FOCUS  MINING IN FOCUS Cryo-microscopy performed in the lab of Lena Kourkoutis, assistant professor of applied and engineering physics, revealed that the technique produced dendrite-free batteries. Zhengyuan Tu, a doctoral student who led the research, says the interface offers several advantages beyond simply stabilising the battery. “The target was to find a facile process to not only protect the pristine anodes, but to also be able to store additional energy,” says Tu. “Tin and other elements have long been exciting candidates for energy storage by readily forming alloys with lithium, so this led us to the concept that a tin interface on lithium would not only offer protection, but added electrochemical activity.” Prolonging battery life Unlike other artificial interface materials, tin is easier to apply during the manufacturing process because it requires a minimal amount of specialised equipment and processing, according to Tu. Testing of the tin interface on a lithium anode revealed a battery life cycle of more than 500 hours at a current density of 3 milliamperes per square centimeter. The test was repeated without the protective interface and the battery lasted just 55 hours. The research team reported that the source of the improvements was the ability of lithium to rapidly alloy with tin, which facilitated more uniform lithium deposition when the anode was recharged. Dendrite- Alphamin’s Bisie tin project in the DRC is coming online later this year. 40  African Mining  October 2019 40  African Mining  October 2019 www. africanmining.co.za