In-situ polymerization to prepare reduced graphene oxide/polyaniline composites for high performance supercapacitors

•Green and environmental-friendly natural green tea polyphenols (GTPs) was used as the reducing agent and stabilizer for GO.•TrGO provides graft-sites for in-situ polymerization of polyaniline (PANI) through Mannich reaction.•The electrochemical performance of composites containing covalent bonds is significantly better than that of non-covalent bonds.•P-phenylenediamine adjusts the morphology of PANI to affect the electrochemical performance of composites.