Home-made Giant batteries
Just a further thought.
Here are some suggestions for area you might like to research.
Switch mode powersuplies.
Why is AC used on the power grid ?
How a Tesla Coil works.
Why does a spark gap have negative resistance ?
If a Tesla Coil can be used to transform relatively Low voltages into very high voltages would it be possible to use one in reverse ?
I spent many happy weeks about 20 years ago tuning spark gap RF power generators used in diathermy units in Hospitals.