The electrolyte first, which will push charges apart rather than into recombination. The plasma will have far higher resistance than the original internal resistance of the capacitor. The whole thing will just get hot, relatively slowly.
This doesn't sound like you are talking about the potential supercaps at all. The theoretical capacitance of graphene is 550F/gram of graphene. An extraordinary number. This is based on sheets of graphene an atom thick. They are still trying to work out what kind of structure can work with this since graphene sheets want to stick together. They are looking at ides like structures with curved sheets. The dielectric gap is about 1 nanometer in this theoretical capacitor. Graphene is extraordinarily strong and so the physical stress is extreme.
Do you believe that if the structure holding two opposing charges 1 nanometer apart breaks down, the charges will take their time travelling the diameter of a handful of atoms? I suggested the charge could cross in nanoseconds which is very slow for that gap.
Ok, lets say I am wrong.
Lets say things like the Graphene supercaps are intrinsically safe.
"You can hold 10 times the energy density of TNT in your pocket held apart by a 1 nanometer dielectric and it is incredibly safe!. If this capacitor fails, an App will message you to give you warning. "
"You can drive you kids in a car with a battery holding the equivalent of 500 kG of TNT and it is totally safe!".
"Firefighters can walk up to a burning capacitor powered car battery when the battery is at 250 degrees C with no fear of that the 2000 MegaJoules of energy about to be released is dangerous".
(Just using 250 deg C because some of the current graphene caps in development use plastics in the construction.)
That is incredible news. It is truly amazing! There must be capacitor developers who cannot stop talking about this.
But no-one is talking about it. No flashy website mentions failure modes. If I am wrong, can you find me a single capacitor developer who explains why these future supercapacitors are safe? How it is impossible to make a bomb out of a supercapacitor?
I would absolutely love to be proven totally wrong.
I would love it if a failing future supercap can just calmly vent a bit of electrolyte and suddenly all the energy is ....where?