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Comment by buster | Hacker News Reader

There is a big miscalculation: Graphene seems to be extremely light weight. 1 liter of graphene will definitely not weight 1kg. Wikipedia [1] only gives measures for m²: Graphene is very light, weighing only about 0.77 milligrams per square meter.

[1] https://en.wikipedia.org/wiki/Graphene

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Here[1], the density is said to be as low as 0.03 gm/cc which is the same as kg/liter. That gives a multiplicative factor of 33 over the above calculations, i.e. this could be 33% of the energy density of lithium ion batteries. Not bad.

[1]: http://www.strem.com/uploads/resources/documents/graphene_na...

Energy per liter also is an important factor. Your mobile would float, but it also would be the size of your lower arm. Maybe, you should wear your battery as a jacket or a pair of trousers?

A square meter of a single-atom-thick layer of graphene isn't very relevant. Expect the final product to have a volumetric density in the neighborhood of graphite or diamond.

Probably closer to graphite, as to my knowledge graphite is literally just layers of graphene.

You need to separate each layer with an insulator to be effective, otherwise you could just use graphite.

Graphene is also very thin. If you created a box of graphene, it would naturally have about the same weight as diamond or coal (plus or minus 100%, maybe, but certainly not orders of magnitude less).

Probably not minus 100% :-)

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