Electrochemical deposition of highly loaded polypyrrole on individual carbon nanotubes in carbon nanotube film for supercapacitor

•Electrochemical pretreatment of CNT film to get loosely structured ECNT film.•Electrodeposition of highly loaded PPy on individual carbon tubes in ECNT film.•Large capacitance of 965.3 mF cm−2 at 1 mA cm−2 for core-shell structured ECNT/PPy.•85.1% capacitance retention upon 20 times current increase for ECNT/PPy.•High energy density of 3.63 mWh cm−3 at 13.86 mW cm−3 for ASC with ECNT/PPy anode.