How many years away are EV ultracapaciters?
Well currently graphene ultracapacitors have very high energy densities close to that of nickel metal hydride batteries, graphene is very expensive right now but new manufacturing techniques are making it cheaper. The problem is that i don't see any new materials that could replace graphene in a long time and right now the limiting factor in energy storage of ultracapacitors is the reduction potential (the voltage at which the electrolyte in the capacitor will break down into its original components e.g. H2O - H2 + O) the energy that the capacitor stores is: E (Joules) C (Farads) / 2 * V (Volts) ^ 2 So as you can see doubling the voltage quadruples the capacity, right now ultracapitors can pull off about 2.71V with an organic electrolyte of Acetonitrile. A new electrolyte needs to be constructed that allows a higher working voltage but it is impossible to tell when that may come, i would say in approximately 5-10 years.
