A team at Cambridge University has developed a breakthrough battery which could double the life of mobile devices - and make them cost less.
Up to 40% of the the cost of current batteries is taken up by the positive electrode - the cathode - which is normally made of lithium and a metal oxide, usually cobalt, manganese or nickel.
The Cambridge team instead used a composite of sulphur and nanostructured carbon for the electrode.
By doing so they were able to dramatically cut the cost - and achieve double the energy density.
"Using sulphur instead of the materials currently used in lithium-ion batteries could substantially reduce production costs, as sulphur is a fraction of the cost of other materials," said Dr Can Zhang, one of the developers of the material.
"Additionally, compared with conventional lithium-ion batteries, the carbon-sulphur electrodes achieve double the energy density per unit of weight."
The new cathodes are made by growing a "forest" (their word) of carbon nanotubes on a layer of metal foam.
The team explains:
"The CNT forest provides excellent electrical conductivity, and acts as a three-dimensional scaffold into which the sulphur is injected in order to form the cathode.
The sulphur is trapped within the scaffold in the form of small particles which store electrons. The pore structure of the metal foam, combined with the dense vertical packing of CNTs, provides a labyrinth with a large surface area for the retention of electrode material."
The problem with sulphur-based batteries has usually been the low number of charge cycles of which they are capable before needing to be replaced. The new batteries up this number from 80 to 250 - still way behind the contventional battery's 500 cycles, but much closer.
The team are now working on inreasing this number to achieve a commercially viable battery. Over the next two years the 'CamBattery' commercial team will work on building a production machine - with the possibility of handheld devices gaining the tech soon after.
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