Foldable supercapacitors from triple networks of macroporous cellulose fibers, single-walled carbon nanotubes and polyaniline nanoribbons

We report foldable supercapacitor electrodes using a macroporous cellulose fiber network, Kimwipes®, as the scaffold through a simple “dip-absorption-polymerization” method. Single-walled carbon nanotubes (SWCNTs) wrapped around the cellulose fibers as the conductive skin, while ultrathin (~50nm) and ultralong (tens of microns) polyaniline (PANI) nanoribbons were synthesized in situ between macroporous cellulose fibers and interpenetrated within the SWCNT network. The hybrid material showed good volumetric (40.5F/cm3) and areal capacitance (0.33F/cm2), which was attributed to the synergistic effect between electron transport within the SWCNTs network and fast charge transfer of the PANI nanoribbons. The paper-based hybrid electrode was highly flexible and compliant; it could be folded back and forth as an origami crane up to 1000 times without mechanical failure or loss of capacitance. We believe that the combination of triple networks and the unique morphology of PANI nanoribbons played critical roles to the repeated foldability. Finally, we assembled six all-solid-state supercapacitors based on the SWCNT/PANI nanoribbon paper electrodes connected in series, which lighted LED before, during and after folding for 500 times.