As electric vehicles continue to grow in popularity, scientists see great potential in lithium-sulfur batteries as a more environmentally friendly way to power them. This is because they don't rely on the same expensive and difficult-to-source raw materials, such as cobalt, but other problems relating to their stability has held the technology back so far. Engineers at Drexel University have made a breakthrough they say takes these batteries closer to commercial use, by leveraging a rare chemical phase of sulfur to prevent damaging chemical reactions.

Lithium-sulfur batteries hold a lot of promise when it comes to energy storage, and not just because sulfur is abundant and less problematic to source than the cobalt, manganese and nickel used in today's batteries. They may offer some significant performance gains, too, with the potential to store several times the energy of today's lithium-ion batteries. But there is one problem that scientists keep running into, which is the formation of chemical compounds called polysulfides.

As the battery operates, these make their way into the electrolyte – the solution that carries the charge back and forth between the anode and cathode – where they trigger chemical reactions that compromise the battery's capacity and lifespan. Scientists have had some success swapping out the carbonate electrolyte for an ether electrolyte, which doesn't react with the polysulfides. But this poses other problems, as the ether electrolyte itself is highly volatile and contains components with low boiling points, meaning the battery could quickly fail or meltdown if warmed above room temperature.

The chemical engineers at Drexel University have been working on another solution and it starts with the design of a new cathode, which can work with the carbonate electrolytes already in commercial use. This cathode is made from carbon nanofibers and had already been shown to slow the movement of polysulfides in an ether electrolyte. But making it work with a carbonate electrolyte involved some experimentation.

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