polymers Article Nanoforest: Polyaniline Nanotubes Modified with Carbon Nano-Onions as a Nanocomposite Material for Easy-to-Miniaturize High-Performance Solid-State Supercapacitors Piotr Olejnik 1,2,*, Marianna Gniadek 2 , Luis Echegoyen 3 and Marta E. Plonska-Brzezinska 4,* 1 Institute of ...