Batteries made from recycled bulletproof vests provide five times more energy

And a ten-year lifespan.
Chris Young

Researchers from the University of Michigan made a new breakthrough in lithium-sulfur batteries leading to a fivefold increase in battery energy density, a press statement reveals.

The new development would provide a more powerful as well as more sustainable alternative to lithium-ion batteries, which are reliant on unethical cobalt mining operations and emit a large amount of CO2 emissions during production.

Batteries made from recycled Kevlar

The scientists used a network of aramid nanofibers, recycled from Kevlar, which is typically used in bulletproof vests, to stabilize the chemical reaction between the lithium anode and the sulfur cathode in their battery. They outlined their new method in a paper published in Nature Communications.

On top of the improved overall capacity, the scientists say the battery has a more than 1,000 charge cycle. They estimate that it would have a battery life of 10 years when fitted into an electric vehicle. "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," Nicholas Kotov, project lead, said in a statement. "The challenge nowadays is to make a battery that increases the cycling rate from the former 10 cycles to hundreds of cycles and satisfies multiple other requirements including cost."

Using an aramid membrane, the researchers were able to prevent the formation of lithium-sulfur, also known as polysulfides, in the battery, which would reduce its overall capacity. At the same time, this membrane allowed lithium ions to flow from the lithium to the sulfur and back.

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A 'nearly perfect' battery

The University of Michigan researchers also point out that the batteries can be produced by recycling bulletproof vests and other products made using Kevlar. Sulfur is also much easier to obtain than cobalt, meaning their batteries can be produced in a more ethical and sustainable fashion.

Professor Kotov has filed a patent application for the aramid membrane and he even plans to found a company to market the new technology. He explained that the battery design is "nearly perfect" and it reached the theoretical limits of the technology when it comes to capacity and efficiency. If the technology does eventually hit the market, it will join the likes of Michigan startup Our Next Energy's prototype battery aimed at reducing dreaded "range anxiety." According to Kotov, "achieving record levels for multiple parameters for multiple materials properties is what is needed now for car batteries. It is a bit similar to gymnastics for the Olympics — you have to be perfect all around including the sustainability of their production."

"Biomimetic engineering of these batteries integrated two scales—molecular and nanoscale. For the first time, we integrated the ionic selectivity of cell membranes and the 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

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