Bioinspired strengthening and toughening of carbon nanotube@polyaniline/graphene film using electroactive biomass as glue for flexible supercapacitors with high rate performance and volumetric capacitance, and low-temperature tolerance

Natural nacre built up with a brick-and-mortar architecture, exhibiting extraordinary strength and toughness, provides an inspiration to construct high-performance multifunctional films for flexible energy storage and portable electrical devices. In the present work, a nacre-mimetic graphene-based film (CNT@PANI/rGO/TA) is fabricated following this idea, wherein electroactive biomass tannin (TA) serves as glue, accompanied by the "mortar" polyaniline wrapped carbon nanotubes (CNT@PANI), to stick the reduced graphene oxide (rGO) "bricks" together. Benefiting from the thin layer of PANI on CNTs, the CNT@PANI nanowires intercalate into the rGO interlayers thus interlocking the nanosheets, and resulting in a well-defined porous multilayered structure. The obtained CNT@PANI/rGO/TA film exhibits both high mechanical strength (174.6 MPa) and toughness (9.17 MJ m(-3)). Meanwhile, the all-solid-state flexible supercapacitor assembled with CNT@PANI/rGO/TA demonstrates a high capacitance of 548.6 F cm(-3) and an outstanding rate performance of 70.5% from 1 A g(-1) to 50 A g(-1). Even at -40 degrees C, the specific capacitance of the supercapacitor is up to 454.9 F cm(-3), approximately 83% of the capacitance delivered at room temperature. The strategy of using electroactive biomass as glue to construct a nacre-mimetic graphene-based film with high strength, toughness and energy storage performance is proved to be straightforward and effective.