Yes, the dielectric IS everything that really matters, and the measure of it is the dielectric constant of the material (for storage of energy in the polarization of the its molecules) and its insulating properties, which determine the maximum voltage that it can support without breaking down.
But the 5-minute charge is a joke, unless you have your own nuclear power plant. Others have offered some calculations and estimates of what it would require, so I don’t need to pile on.
“But the 5-minute charge is a joke, unless you have your own nuclear power plant. Others have offered some calculations and estimates of what it would require, so I don’t need to pile on.”
If you had a similar unit in your house for emergency backup, you would not need your own nuclear power plant. 5 minute recharge would be dangerous and would require significant engineering but is posible. A more likely scenario would be overnight recharging at home and unit exchange on the road.