Better Li-ion batteries thanks to magnetic alignment
7/5/2016, Milan Šurkala
Even though there are many attempts how to invent a new type of batteries, Swiss researchers rather tried to improve already existing Li-ion technology using metal nanoparticles. The three-fold increase was achieved in the first tests.
Swiss Paul Scherrer Institute PSI in Villigen and the ETH Zurich researchers are members of many scientific groups that want to improve the battery technology. In a comparison with other groups that are trying new materials for batteries, these Swiss researchers want to improve already existing Li-ion technology and discover its real potential. The new version of Li-ion battery optimizes its negative electrode that is made of graphite.
source: Magnetically aligned graphite electrodes for high-rate performance Li-ion batteries (Nature Energy)
In conventional batteries, the graphite plates are not organized and because of that, the flow of lithium ions is quite complicated when the battery is charging (ions are traveling from positive cathode to negative anode) and when the battery is used (ions are travelling in the opposite direction). If the plates are arranged vertically and parallel to each other, the detours of ions are minimized and the battery can have much better properties. It can be charged faster and according to the first laboratory tests, the capacity can be three times larger. Nevertheless, the scientists said that they do not expect such an improvement in real world. They expect that real Li-Ion batteries with the new technology can have about 30-50% better capacity (density) than today's versions. Even these values are quite good.
The question is how to align all these graphite plates in the same way. The researchers covered them with iron oxide nanoparticles suspended in ethanol that are sensitive to magnetic field and that allows them to change the direction using the magnetic field. The graphite plates should stay in their new position after they are removed from ethanol suspension in a drying process. The chemical composition of the batteries is the same with the exception of metal nanoparticles.