Home-made Giant batteries
Booster, that certainly is a wild idea. I have no idea how much electrical energy you could get from a cloud, but I would guess that it's not enough to be worth sending a rocket up to get it.
There are technical problems with trying to use either capacitors or batteries to store the energy. Capacitors can be charged quick and they can be configured to store high voltages. The disadvantage of capacitors is that they are more expensive than batteries and store less energy.
As for making a battery out of a barrell - you can do that with lead plates and electrolite solution as you described - like a big car battery. I'm not sure what type of electrolite. I can't imagine how you would get a battery (which can be used for slow charging rates & low voltages) to store the energy from a lightning strike.