Lithium-ion batteries power many modern devices from cell phones, to cars, laptops, and a multitude of portable electronics. But their power density is less than ideal. And there appears to be another, perhaps more promising energy storage option on the horizon: lithium-sulfur batteries.
Lithium-sulfur batteries use cheaper materials than lithium-ion, they weigh less, and have a higher power density. In fact, a lithium-sulfur cell can store almost double the energy of a lithium-ion cell for the same mass, making the technology favorable for energy storage applications in which power density is an important factor.
In Lithium-sulfur batteries lithium dissolves from the anode surface during discharge, and reverse plates to the anode while charging. Whereas lithium-ion batteries typically only accommodate 0.5–0.7 lithium ions per host atom, each sulfur atom can host two lithium ions. As a result, Lithium-sulfur allows for a much higher storage density. In the past, however, there has been one major challenge: the amount of charge decreases with use. Lithium–sulfur batteries have been limited by poor charge cycle stability.
Previous efforts to stabilize battery cycling used protective coatings to keep the compounds separate and contained. These contributed to the weight of the device and had performance-related consequences.
In a recent study published in the journal Proceedings of the National Academy of Sciences, a research team including Yale University chemistry professor Victor Batista explains that they’ve produced a one-atom thick composite film that increases the durability of lithium-sulfur batteries.
The film, made of graphene and an organic polymer, prevents the lithium-sulfur compounds from leaching into the electrolyte and decreasing the battery’s performance. The nanosheets were able to effectively “alleviate capacity fading over battery cycling without compromising the energy or power density of the entire battery.”
“The amazing thing is that with these materials, we were able to make batteries that have a record of stability with a minimum amount of membrane,” Batista told Scientific American.
The development of these graphene oxide nanosheets is an exciting advancement, ideal for applications in which energy density is critical. What potential uses can you envision?