[JumpCrisscross]

No need for batteries when supercapacitors will do.

[aitchnyu]

Which supercapacitors are sold and have car-scale energy?

[tgv]

So you might have to wait an hour for your 5 minute charging time? Doesn't sound like a killer feature.

[mjmas]

the idea would be to slowly charge the capacitor to its capacity in the breaks between the charger being used. That way when you arrive at the charger, the capacitor would be fairly full and able to quickly transfer that energy to your car. The charger would then replenish that capacitor more slowly (meaning that the charger wouldn't be able to be used for a bit).