Researchers increase lifespan of lithium-sulfur batteries
Technology has advanced markedly since the dawn of the silicon age, but our portable gadgets and gizmos are still largely held back by the limitations of their power source. Scientists at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden report progress in this regard, with the development of a new longer-lasting lithium-sulfur battery that has the potential to outperform lithium-ion batteries, at a lower cost.
Though more powerful and less expensive to produce than the more widely used lithium-ion batteries, lithium-sulfur batteries have typically sported a comparatively poor lifespan. However, the Dresden-based researchers have successfully developed a new design that increases the charge cycles of lithium-sulfur batteries by a factor of seven.
“During previous tests, the batteries scarcely crossed the 200-cycle mark,” said Dr. Holger Althues, head of the Chemical Surface Technology group at IWS. "By means of a special combination of anode and cathode material, we have now managed to extend the lifespan of lithium-sulfur button cells to 1,400 cycles."
The anode is made from a silicon-carbon compound instead of the metallic lithium usually used, offering improved stability as a result – a key factor in the performance and lifespan of a battery. The cathode, meanwhile, is composed of elemental sulfur, and as such is cheaper to produce than the cobalt cathodes typically implemented.
Looking ahead to the future, the IWS researchers expect to refine the lithium-sulfur batteries to the point where they reach an energy density of up to 600 watt-hours/kilogram (Wh/kg). This would beat the lithium-ion density record of 400 Wh/kg claimed last year by Envia, and more than double that of Li-ion batteries currently in use.
Beyond potential application in electric cars, the Fraunhofer researchers cite smartphones as an attractive candidate for lighter, cheaper and more powerful lithium-sulfur battery technology, and presumably most other portable electronic devices, too.
"Lithium-sulfur technology might even make electric flying a realistic possibility,” said Althues. “Although such progress is still a long way off.”