Researchers at Drexel University have extended the life of lithium-sulfur batteries. They braided a mat of titanium oxide nanofibers and settled sulfur atoms on them. “This is a significant step forward,” says assistant professor dr. Vibha Kalra. The novel cathode is very conductive and bind polysulfides that form during charging and discharging of the battery and migrate into the electrolyte. This reduced the life of the first lithium-sulfur batteries to a few cycles.
Electromobility For many years researchers around the world have tried in vain to stabilize the sulfur cathode. Because of the energy density unequaled by other types, they promised themselves a decisive boost for the use of electric aircraft. Lithium-ion batteries can not compete with that. Their energy density is totally exhausted, say the researchers around Kalra. Everything that increases capacity and reduces volume has already been implemented. Some would have exaggerated, as the manufacturers of the batteries, the 2016 notebooks and smartphones from Apple or Samsung were burned.
Lithium-sulfur batteries provide five to ten times longer power than lithium-ion batteries. This could help electromobility, which still has problems due to its short range. Even e-planes that carry 100 passengers and more, thus become feasible. The titanium oxide mat ensures that the polysulfides do not roam uncontrollably and destroy the battery. This solution is attractive because it does not increase the weight and hardly affects the costs of production. Because the surface of the cathode increases by the use of the mat, the capacity of the power storage increases.
Gel-like electrolytes Kalra’s team has minimized the risk of the battery burning or even exploding in the event of mechanical injury. This was achieved by the researchers not a liquid electrolyte – this separates the two electrodes from each other – but a gel-like.
“Our design minimizes the capacity losses that occur over time,” says Dr. Vibha Kalra.
These are the main obstacle to the commercialization of the lithium-sulfur battery. After the record-breaking flight of the Zephyr 6 solar aircraft this year, with just under 336 hours in the air, lithium-sulfur batteries came into the public eye.