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new to this StackExchange, but I have a question about graphene batteries / supercapacitor. From my understanding, graphene batteries / supercapacitors (not sure of the difference?) are superior to regular acid-based batteries because they can hold much more energy and also charge and discharge very quickly. I have read that the one of the biggest roadblocks to creating an effective railgun is the lack of quick discharge capability of normal capacitors. Would using graphene materials potentially solve this issue, allowing a railgun to be built in a much smaller (possibly handheld?) package? Really, I'm just looking for information about how graphene could potentially impact the design and capabilities of railguns. Thanks all!

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    \$\begingroup\$ The difference is the same between alkaline batteries and copper wire. And btw. You can use those too to create a railgun... \$\endgroup\$ – PlasmaHH Jan 8 '16 at 19:01
  • \$\begingroup\$ Surely you want Power Density .Energy density is not so important. \$\endgroup\$ – Autistic Jan 8 '16 at 21:23
  • \$\begingroup\$ Both power density and energy density are important for a portable rail gun. You need to store substantial amount of energy and a portion of the energy needs to be transferred very quickly. \$\endgroup\$ – Charles Cowie Jan 8 '16 at 21:30
  • \$\begingroup\$ After answering with reference to superconductors, I wonder if the word "superconductor" in two places in this question was intended to be "supercapacitor?" \$\endgroup\$ – Charles Cowie Jan 8 '16 at 22:05
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The problem with capacitors is not quick discharge capability, it is energy density, and particularly the energy density of types of capacitor that can discharge very quickly.

There are apparently some batteries on the market that use graphene in their design. However, the use of graphene is a research area that some are claiming has great potential, not something that has a huge proven potential.

I believe that there are superconductor-based inductive energy storage systems that have been installed, proven and currently offered for sale. However they are of the scale that would be transported on a large truck or rail car, not something that has potential for anything near hand-held.

It is very doubtful that a useful hand-held rail-gun is any closer to reality than a nuclear fusion powered automobile.

Added information about inductive energy storage

The difficulty with small scale superconductor-based inductive energy storage systems is that there is a substantial balance of system (BOS). The BOS is all of the required components and equipment in addition to the basic energy storage component. Refrigeration equipment and insulation is required to get the superconductive material cold and keep it cold. There are also charging and discharging or energy transfer systems.

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I don't think graphene supercaps are a real product yet. Not something that exists outside a lab that you can buy.

Superconductors are available, if you can stand the price: http://shop.can-superconductors.com/index.php but they have two big limitations.

  • they're not superconducting at room temperature. They have to be kept in liquid nitrogen. That ruins the portability, and even if you did have superconducting rails, the act of firing the railgun tends to heat the projectile to plasma temperatures, ruining the superconductor.

  • they're not ductile, so they have to be cast in place and are generally a pain to manufacture.

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