The innovation could significantly boost the range of electrical vehicles

Jan 10, 2014 20:11 GMT  ·  By

Lithium-sulfur (Li-S) batteries hold great promise for use in electrical vehicles, but experts say that a few technical difficulties are still preventing their wide-scale adoption on the market. A new study may have addressed one of these challenges, bringing Li-S-powered cars one step closer to reality. 

In a research conducted by investigators with the US Department of Energy's (DOE) Pacific Northwest National Laboratory (PNNL), a team of experts developed a hybrid anode capable of boosting the storage capacity in this type of batteries by more than 400 percent.

If applied to the real world, such an increase would more than double, even triple, the range of electric vehicles, one of the most significant obstacles preventing the use of Li-S batteries is these cars. At this point, lithium-ion batteries are still the preferred power-storing device of choice for manufacturers.

The performances and overall design of the anode were presented in a paper published in the January 9 issue of the top scientific journal Nature Communications. Another issue that remains to be resolved in Li-S batteries is their inability to go through very many charge-discharge cycles.

“Lithium-sulfur batteries could one day help us take electric cars on longer drives and store renewable wind energy more cheaply, but some technical challenges have to be overcome first. PNNL's new anode design is helping bringing us closer to that day,” says Jun Liu, a PNNL Lab fellow and corresponding author of the new paper.

The lab's investigation was centered on developing a shield on the anode that stops the leakage of sulfur. This phenomenon occurs in the cathode as well, and scientists working on improving Li-Ion batteries have been trying to stop it through a variety of methods for several years

Rather than focusing on cathodes (the positively-charged electrode of a battery), the PNNL group centered its efforts on the negatively-charged electrode, called an anode. The shield developed in the new study is made up entirely out of a carbon compound called graphite, which can be found in pencil lead.

Graphite looks like a thin matrix of connected carbon molecules. It represents one of the most important sources of graphene, the 2D hexagonal carbon lattice known for its good physical properties.

“Sulfur is still dissolved in a lithium-sulfur battery that uses our hybrid anode, but that doesn't really matter. Tests showed a battery with a hybrid anode can successfully be charged repeatedly at a high rate for more 400 cycles, and with just an 11-percent decrease in the battery's energy storage capacity,” Liu concludes.