Monday, December 6, 2010

Graphene Battery Advance

This is of course very promising simply because it is fast.  I will not be surprised if some clever design will also raise energy density dramatically since we are still just doing what is tried and true. 

Most important, is that this will surely give us a rapid recharge battery that will be up to plug and play architecture.  What I mean by that is that we can design in an onboard converter to draw AC power in a few seconds and then plug into the application.  Still difficult but a fast battery make the effort worthwhile in a way that plug and wait battery never could.  There was no incentive for eliminating the hardware.

In the event, graphene is going to be muscling into the battery party and possibly eliminating the exotics completely.  To start with it is naturally lighter, is many times faster from the beginning and starts by matching present performance of one of the competing protocols.    It is not quite yet taking full advantage  of super capacitance but when you recall that it is naturally been engineered in the appropriate dimensions it is going to be surprisingly easy to take forward.

There is still work to be done here but my first thought on coming across graphene was to think battery and this is beginning to flesh it out.

NOVEMBER 26, 2010

A supercapacitor with graphene-based electrodes was found to exhibit a specific energy density of 85.6 Wh/kg at room temperature and 136 Wh/kg at 80 °C (all based on the total electrode weight), measured at a current density of 1 A/g. These energy density values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face. The curved morphology enables the formation of mesopores accessible to and wettable by environmentally benign ionic liquids capable of operating at a voltage over 4 Volts.

Technologically, the nano graphene-based, ionic liquid-enabled supercapacitor provides a specific energy density of 85.6 Wh/kg (based on the total electrode weight) at room temperature and 136 Wh/kg at 80°C, both measured at a current density of 1 A/g (corresponding to a high charge/discharge rate).

a) These are the highest energy density values ever reported for nano carbon material-based supercapaitors dominated by the electric double layer (EDL) mechanism, with minimal contribution from any redox-type pseudocapacitance mechanism.

b) These energy density values are comparable to that of the Ni metal hydride battery. This new technology provides an energy storage device that stores nearly as much energy as in a battery, but can be recharged in seconds or minutes. We believe that this is truly a breakthrough in energy technology.

The theoretical capacitance of graphene is 550 F/g (Farads per gram).

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