Rare Form Of Sulfur Triples Capacity Of EV Batteries

Engineers at Drexel University have made a breakthrough they say takes lithium-sulfur batteries closer to commercial use by leveraging a rare chemical phase of sulfur to prevent damaging chemical reactions and tripling their capacity, Nick Lavars reported for New Atlas.

Photo Insert: Lithium-sulfur batteries could be the energy storage devices of the future, if they can get past a chemical phenomenon that reduces their endurance.

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.

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.

The study was published by the journal Communications Chemistry.

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.

The cathode remained stable across a year of testing and 4,000 charge-discharge cycles, which the scientists say is equivalent to 10 years of regular use.

The prototype battery the team made featuring this cathode offered triple the capacity of a standard lithium-ion battery, paving the way for more environmentally-friendly batteries that allow electric vehicles to travel much farther on each charge.

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