Clay key for better supercapacitors

A composite of clay and an electrolyte serves as both electrolyte and a separator in a supercapacitor. Photo credit: Ajayan Group/Rice University

A composite of clay and electrolyte serves as both electrolyte and separator in a supercapacitor. Photo credit: Ajayan Group/Rice University

Supercapacitors have been in the news a lot recently, with researchers and investors alike hoping they can combine the rapid charging and high energy densities of conventional capacitor devices with the slow release of energy associated with batteries.

One drawback, even at this early stage in the drive to commercialise emerging approaches, is the restrictive temperature range of supercaps, relying as they do on the gel or liquid electrolytes that characterise their conventional cousins. Now, though, inventive researchers at Rice University may have found the answer. And they literally dug it straight out of the ground.

A clay-based membrane, says the team, has been used to produce a supercapacitor which stays stable at up to 200ºC, making it ideal for energy storage in extreme environments such as space, battle conditions and oil drilling.

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