A spoonful of sugar strengthens lithium-sulfur batteries
Sweets don’t always have to hurt. That applies at least to batteries, as an Australian research team was able to show impressively.
Lithium-sulfur batteries are lightweight and have a high charging capacity. With up to five times the capacity of the same size, they would be far better suited for use in electric vehicles than the current lithium-ion batteries.
The catch: lithium-sulfur batteries break down too quickly. With only between 50 and 100 charging cycles, there is no need to even think about using it in electric cars. We were able to report a breakthrough in technology as early as February 2021. A Korean research team was able to show that the inherent self-destruction process of the lithium-sulfur battery could be slowed down significantly by adding cobalt oxalate.
Now a team of scientists at Monash University in Australia has found a way to prevent the negative lithium electrode from self-destructing. Up to now, this has been destroyed by sulfur impurities, which form a layer on the electrode and thus interrupt its conductivity. So the team was looking for a substance that would prevent the build-up of the deposit.
They found it in a sugar spoon. The sugar was worked into the material of the electrode. From then on, no more sulfur could deposit on the electrode. The team sets out the process in detail in a work Nature before.
Schematic representation: red arrow shows effect without, green arrow with sugar. (Screenshot: t3n / Nature)
Lithium-sulfur batteries constructed in this way should easily reach 1,000 charging cycles and more. It is clear to the researchers at Monash University that that is not enough. After all, modern lithium-ion batteries in electric vehicles can last for up to 2,000 charging cycles, which corresponds to around ten years of driving.
That is why they want to develop further protective measures for the lithium metal anode. About a year ago, the same team had developed a method to stabilize the positive sulfur electrode by integrating a binding agent that ensures that the electrode can withstand the movement of material during the charging process.
The appeal of the technology is obvious at first glance. Lithium-sulfur batteries are at least 20 percent cheaper to manufacture than those with lithium-ion technology. In addition, they should have up to five times the capacity. An electric vehicle that has a range of around 500 kilometers with current batteries would be able to drive around 2,500 kilometers on one charge with the cheaper lithium-sulfur batteries.
Alternatively, the weight of the vehicle could be reduced with the same range. However, this effect is partly eaten up by the fact that the volumetric energy density of lithium-sulfur batteries is only about half that of lithium-ion batteries. A vehicle with today’s weight and a range of around 1,200 kilometers would therefore appear realistic.
