These are lithium cells fabricated in a fancy way. This sort of nanoscale construction of the electrode materials affords massive surface area so you get advantages like improved capacity, power, lifetime, etc.
As with all lithium cells these are suited to applications which benefit from high energy density and low power, i.e. laptops, mobile phones etc.
'Mega-efficient' is probably a bit misleading, don't get carried away thinking all of a sudden there's a new portable energy source with the potential to replace all existing batteries!