Researchers led by Professor Kim Hee-Tak at the Korea Advanced Institute of Science and Technology (KAIST) in South Korea have developed a lithium-sulfur (Li-S) battery with a a doughnut-shaped active material structure that remains functional over 600 charge-discharge cycles.
Donut-shaped lithium sulfide (Li2S) cathodes were combined with graphite anodes in a highly concentrated electrolyte solution to enhance the energy density and life-cycles of the batteries. The cathodes showed outstanding charge and discharge reversibility due to the improved transfer of lithium ions. The use of the highly concentrated salt electrolyte resulted in the formation of a stable film on the surface of the graphite electrode, which prolonged its durability. Kim’s team was able to achieve a 30 percent higher energy density than that of conventional lithium ion batteries and a battery life cycle of more than 600 cycles.
“We have demonstrated that the application of low-cost sulfur compounds to lithium ion batteries can improve both energy density and lifecycle of those batteries simultaneously,” said Kim.
Standard lithium ion batteries have charge densities that are too low for practical use in electric vehicles leading researchers to examine Li-S batteries which potentially have a much higher energy density. However, the durability of Li-S batteries is low due to the properties of the lithium metal cathode. The researchers state that their donut-shaped lithium sulfide-based electrode can be manufactured using low-cost raw materials and a single heat treatment process. The electrode can also be used in existing lithium ion batteries.
The findings are published in Advanced Science, “An Ultrahigh Capacity Graphite/Li2S Battery with Holey-Li2S Nanoarchitectures”.