Polypyrrole/carbon nanotube nanocomposite enhanced the electrochemical capacitance of flexible graphene film for supercapacitors

► A hierarchical flexible film composed of GN, PPy and CNT was fabricated. ► The coaxial PPy/CNT nanocables homogeneously insert into the GN sheets. ► The novel film has unique advantages to deliver good electrochemical performance. ► The mass and volume specific capacitances of GN-PPy/CNT reach 211 F g−1 and 122 F cm−3. ► The GN-PPy/CNT shows only 5% capacity loss after 5000 cycles.