Integrating polyacrylonitrile (PAN) nanoparticles with porous bacterial cellulose hydrogel to produce activated carbon electrodes for electric double-layer capacitors

Activated carbons, BC-PANnp-ACs and BC-PANnp-KACs, have been synthesized from a composite (BC-PANnp) derived from bacterial cellulose (BC) and polyacrylonitrile nanoparticles (PANnp) by physical and chemical activation, respectively. Commercially available nata de coco has been used as the source of BC whereas PAN nanoparticles of ca. 100 nm have been synthesized in situ in the BC gel by emulsion polymerization which covers the nanofibers of BC. FE-SEM images confirm that hierarchical lamellar structure of BC is retained in the activated carbon frameworks. Detailed electrochemical studies carried out with the electrodes designed with the activated carbons reveal their good performance as electric double layer capacitors (EDLC) with fast response and high-speed charging and discharging. The activated carbons prepared by KOH activation have much higher specific surface area and exhibit better electrochemical properties compared to the carbon materials obtained by CO2 activation or the commercially available YP50F activated carbon derived from coconut shell. The three-dimensional network structure peculiar to BC reduces the grain boundary resistance between the carbonized PAN nanoparticles in these composites compared to PAN nanoparticles carbonized alone imparting good conductivity without the addition of a conductive agent.