A smart new coat for a solid-state lithium battery

Chinese researchers have figured out how to make an ultra-thin membrane for solid-state lithium batteries, allowing them to become more energy-dense.

Solid-state lithium batteries are expected to be safer than traditional lithium-ion batteries, but there are still problems to solve in finding the right chemistry.

They’ve published their findings in Energy Material Advances.

It revolves around improving the electrolyte of solid-state batteries: the part that transfers particles between the anode and the cathode.

Traditional battery electrolytes are liquids or pastes, but in solid-state batteries, they’ll be less flammable solid substances. One possible candidate for solid electrolytes is sulphur-based material, or sulphides.

“The development of thin sulphide solid electrolyte layers is imperative,” says co-author Xiayin Yao, a professor at the Chinese Academy of Sciences’ Ningbo Institute of Materials Technology and Engineering.

At the moment, the brittleness of these substances means that it’s hard to make membranes of sulphides thinner than half a millimetre – which hampers the battery’s capacity to store energy.

But Yao and colleagues have made a membrane that’s just 0.04mm thick – less than a tenth of typical sizes.

They’ve used binders in their substance made of carbon-based polymers. They then used a slurry-based system to coat the battery electrodes, resulting in a thin, solid, coating.

The researchers have applied this binder to an experimental lithium and magnesium solid-state battery.

The battery kept a capacity of 77% after being charged and discharged 1,000 times.

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