Wood based quasi-solid-state Zn-air battery with dual honeycomb-like porous carbon and cationic nanocellulose film

Conversion of low-value biomass to hierarchically porous carbon-based materials for oxygen reduction reactions (ORR), without using conventional template methods, is of particular significant for energy storage technology. Herein, dual honeycomb-like porous carbon inspired by multiscale structure of wood was assembled with cationic nanocellulose film into Zn-air battery. Nitrogen-doped hierarchically porous carbon was obtained by a simple two-step process involving alkaline extraction and pyrolysis with NH 4 Cl. Alkaline extraction was utilized for partially degrading lignin and heterosaccharide from unprocessed wood to create a porous wood with numerous nanopores and 3D loose structure. The inner and outer parts of obtained porous wood were further pore-optimized and doped with NH 4 Cl by a consequent pyrolysis step. The resulting carbon-based material (AHWC) possessed high specific surface area (1601.8 m 2 g −1 ), well-developed hierarchical porosity, and high N content enabled excellent electrocatalytic oxygen reduction performance. Compared with commercial Pt/C catalysts in KOH electrolyte, AHWC exhibits nearly two times higher kinetic currents in the low overpotential region, comparable number of transferred electrons, and significantly higher operating stability. This carbon-based material also showed an excellent capacity and energy density equal to 792 mA h g −1 and 927 W h kg −1 , together with superior long-term durability (200 h at the current density of 10 mA cm −2 ) when assembled as the active electrode material into a Zn-air battery. Additionally, cationic modified nanocellulose film (C-CNF-M), acting as a solid electrolyte, was assembled with AHWC for a quasi-solid-state Zn-air battery which exhibited excellent specific capacity (672.2 mA h g −1 ), energy density (644.11 W h kg −1 ) and cycling stability (500 min at 1 mA cm −2 ). The AHWC establish a bridge between papermaking and the field of energy storage by green conversion of biomass and fabrication of porous carbon-based materials and cellulose based electrolyte with excellent properties applicable to electrochemical energy devices. • Dual honeycomb-like hierarchically porous carbon (AHWC) has been obtained. • The honeycomb-like structure of pores on the multichannel walls can be controlled. • Abundant defects and interconnect pores in carbon lead to excellent ORR activity. • Cationic modified nanofibers (C-CNF) was prepared as a solid electrolyte. • The Zn-air battery with AHWC showed an excellent cycling stability.