Recycled bulletproof vests may boost the range of electric cars 5-fold

• Research into lithium-sulfur batteries promises to improve the useful life of current batteries.
• The new technology allows a 5-fold increase in energy density over lithium-ion batteries.
• Researchers said they were able to make the prototype thanks to a fiber membrane made of Kevlar.

Batteries can be found in all kinds of devices, ranging from cell phones to electric vehicles.

Currently, they’re powered by lithium ions and are made of polluting materials like lithium or cobalt.

Although electrification is a necessary step towards achieving mid-century climate goals, its technology is still not as sustainable or environmentally friendly as it could be.

At present, large amounts of carbon are emitted during the manufacturing process of batteries — even more than in that of combustion cars, although it’s true that in the long run electric cars are more environmentally friendly.

Car manufacturers have been able to produce cars with a respectable range of up to 700 kilometers. But due to the scarcity of materials and technological limitations, it doesn’t look like these figures will increase much with lithium-ion batteries.

Researchers around the world are working to improve the technology behind batteries, which relies on the efficiency of new materials. The substitution of lithium for sodium and the use of lithium together with sulfur represent the most common avenues of research.

In addition to being, in theory, cheaper materials, they would offer better energy density and be greener than current batteries.

Scientists at the University of Michigan have stabilized the chemical reaction between the lithium anode and the sulfur cathode, achieving a fivefold increase in the energy density of the battery.

To stabilize the reaction, the researchers used a network of aramid nanofibers, recycled from kevlar, the fabric used to make bulletproof vests, among other things, as published in Nature Communications.

The aramid membrane allows lithium ions to flow from lithium to sulfur and vice versa, preventing the formation of polysulfides, which flow into lithium and reduce the battery’s capacity.

In addition, they’ve managed to make this battery withstand the more than 1,000 charge cycles needed to implement it in an electric car. The researchers at the University of Michigan estimated that, if implemented in an electric car, it would give it a useful life of 10 years.

“There are a number of reports claiming several hundred cycles for lithium-sulfur batteries, but it is achieved at the expense of other parameters—capacity, charging rate, resilience and safety,” said Nicholas Kotov, professor of chemical sciences and engineering and project leader, to the University of Michigan News.

“Biomimetic engineering of these batteries integrated two scales—molecular and nanoscale. For the first time, we integrated ionic selectivity of cell membranes and toughness of cartilage. Our integrated system approach enabled us to address the overarching challenges of lithium-sulfur batteries,” he continued.

Kotov described the capacity and efficiency of the prototype as “nearly perfect” as it comes close to the theoretical limits for this type of technology.

Other advantages of lithium-sulfur batteries

Lithium-sulfur batteries are able to tolerate extreme temperatures — both hot and cold.

The batteries are also more sustainable than lithium-ion ones. Through recycling bulletproof vests, it’s possible to obtain the aramid fibers needed for the membrane, and it’s easier to obtain sulfur than the more scarce cobalt used in lithium-ion batteries.

The successful research, funded by the National Science Foundation and the US Department of Defense, has led Professor Kotov to file a patent application for the membrane and he’s also announced his interest in founding a company to market it.