A couple of points.
The eestor unit in question is 50 kwh. Whether you can actually drive 500 miles on it is another question.
Second, it is not a battery and will have different discharge characteristics.
Third, 5 minute charges are posible with either very high amperage or voltage. I’m not saying that it is practical.
They claim they have built in safety features to prevent catastrophic discharge for what it’s worth.
1. If it is 50 kwh then you won’t be going 500miles at 60mph. Frictional losses increase with speed.
2. I have been designing power systems for 25 years and elctricity in large quantities is dangerous period. As you pointed out you can either increase voltage or current (VxI=P). 600 volts is as high as you can go to be considered “Low” voltage. 120 volts is really as high as you can go without being almost always lethal.
Past 600V the standard choices are 4160V, 15KV, 30KV, 60KV, 110KV, 220KV and 500KV.
Anyway anything past 600V is pretty scary and that’s why I like electricians so much, I don’t have to touch that stuff.
The problem is that you have to make a good clean contact in air that it is not too dry and not too wet every time you charge. Once the contacts start to get fouled you will get increasing resistance and than comes the snap crackle Ka-pow!
The only way to make it safe is that the vehicle occupants get out and stand behind a concrete blast wall.