There is no way that ultracapacitors would replace batteries as their energy density is way too low, but the power output makes them complementary products to batteries.

Small ultracapacitor modules could take all of the peak charge (regenerative braking) and discharge (acceleration), potentially doubling the longevity of the battery pack.

Skeleton Technologies demonstrated a small 10 kg module that was able to deliver 100 kW for a few seconds (it's enough to accelerate or decelerate the sports car from 0-60 mph or 60-0).

We visit Skeleton Technologies in Tallinn, Estonia to find out how these remarkable products are made and what they do.
Curved graphene. Yummy.