A Tough Flexible Cellulose Nanofiber Air Cathode For Oxygen Reduction Reaction With Silver Nanoparticles And Carbon Nanotubes In Rechargeable Zinc-Air Batteries

In the present work, a tough flexible thin carbon nanotube/cellulose nanofiber composite paper loaded with silver nanoparticles (CNT/Ag/CNF) is fabricated, which can function efficiently as the flexible air cathode of zinc-air batteries. Such a CNT/Ag/CNF paper made using a liquid-phase reduction method has an excellent conductivity up to 293.17 +/- 32.8 S.m(-1). The results of X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy show that the CNF and CNTs are inseparably intertwined, which contributed to a high tensile strength of 7.47 +/- 0.74 MPa, a fracture strain of 1.67 +/- 0.12%, and excellent folding endurance of the CNT/Ag/CNF paper. The electrochemical tests show that the as-prepared CNT/Ag/CNF paper has excellent catalytic activities and oxygen reduction reaction durability in the O-2-saturated 0.1 M KOH electrolyte. An assembled liquid zinc-air battery using CNT/Ag/CNF as the air cathode exhibits an excellent power density of 70 mW.cm(-2), which is higher than the 59 mW.cm(-2) of a similar zinc-air battery using the Pt/C material. In addition, an assembled flexible all-solidstate zinc-air battery using CNT/Ag/CNF shows a stable open-circuit voltage of 1.5 V at different bending angles. The modified nanocellulose fiber strategy in the present work demonstrates a promising approach to develop tough flexible air cathodes by integrating electrocatalytic substances, which can extend the great applications of the emerging wearable and portable electronic products.