Nuclear batteries a penny...
Honestly who the hell cares about the name of the coin past the first post, the point is that it is small and the important thing besides the size is that uses something different than chemical reaction.
What type of isotope?
Beta or Alpha emitter?
How long until we can have one that produces 1.5 volts, a decade? 5 years?
Is it dangerous as waste?
As somebody else asked, can you produce them using existing nuclear waste?
etc.
People with two or more neurons in work condition do not care about the bloody coin, got lots on my pocket (blame candy dispensers) and they're called f****** small change.