Graphene in new ‘battery’ breakthrough?

Researchers at Hong Kong Polytechnic University claim to have invented a new kind of graphene-based “battery” that runs solely on ambient heat. The device is said to capture the thermal energy of ions in a solution and convert it into electricity. The results are in the process of being peer reviewed, but if confirmed, such a device might find use in a range of applications, including powering artificial organs from body heat, generating renewable energy and powering electronics. Ions in aqueous solution move at speeds of hundreds of metres per second at room temperature and pressure. The thermal energy of these ions can thus reach several kilojoules per kilogram per degree. However, until now, little work had been done on finding out how to tap into this energy and produce power from it.

Zihan Xu and colleagues made their battery by attaching silver and gold electrodes to a strip of graphene – which is a film of carbon just one atom thick. In their experiments, the researchers showed that six of these devices in series placed in a solution of copper-chloride ions could produce a voltage of more than 2 V. This is enough to drive a commercial red light-emitting diode. The technology is quite different to conventional lithium-ion batteries, for example, which convert chemical energy into electricity. “The output of our device is also continuous and it works solely by harvesting the thermal energy of the surrounding copper-chloride ions, which, in theory, is limitless,” says Xu.

According to the researchers, the battery works rather like a solar cell. The copper ions (Cu2+) continually collide with the graphene strip in the battery. This collision is energetic enough to displace an electron from the graphene. This electron can then either combine with the copper ion or travel through the graphene strip and into the circuit. Since electrons move through graphene at extremely high speeds (thanks to the fact that they behave like relativistic particles with no rest mass), they travel much faster in the carbon-based material than in the ionic solution. The released electron therefore naturally prefers to travel through the graphene circuit rather than through the solution. This is how the voltage is produced by the device, explains Xu.

via Graphene in new ‘battery’ breakthrough?

This entry was posted in Chemistry, Technology. Bookmark the permalink.

2 Responses to Graphene in new ‘battery’ breakthrough?

  1. Anonymous says:

    Considering the miniscule size of the graphene strip; to me this this would be a very important factor in determining the useful life of the battery. I take it that the effect of heat on the battery could be a small worry since it operates mainly on the heat energy of the copper ions in solution. Would this battery be affected by the surrounding temperature without having a temperature controlled package into which it is built? I believe the theory here is that it never needs recharging. Also, the construction of it’s casing would have to be robust enough to keep external sources from damaging the internal components and causing failure. That along with the aggressive nature and speed of the ions striking the strip. Not really knowing the type or expense of the materials needed to create a realistically useful power source.

  2. Deskarati says:

    All very good questions. I expect it will be quite some time before we see any of the ‘good ideas’ for the use of graphene come to fruition. Still, it seems likely, from the amount of research being funded, that quite a number of new inventions will eventually come from the use of graphene.

Comments are closed.