In my world Humanity has spread across the solar system and extra terrestrial states are common.
I want trade to exist between worlds because trade is flipping amazing, so I have spent days dreaming up the best inter-planetary currency. Fiat money seemed good at first, until I considered why on earth (or in space) a moon you've newly opened relations would trade their precious metallic deuterium and rare earths for your 1's and 0's.
Commodity Money I was wary of, what with one world's carbon lumps being another world's diamonds, but then my mind became fixated on the one commodity for which there was both perpetual and universal need: Electricity, the energy currency of man.
I am currently trying to determine whether or not the idea is practicable or not, so I've come to ask the good people of Stack Exchange
Some notes ~
This question is about the use of electricity as currency its self, not as a means of backing currency
The people of this world have access to most if not all chemically possible battery types, including lithium-fluorine batteries and smes using metallic hydrogen
Assume the energy-value equivalence isn't something crazy like 1000 kilowatt hours per shilling or something like that