Cotton pad-derived large-area 3D N-doped graphene-like full carbon cathode with an O-rich functional group for flexible all solid Zn–air batteries

Abstract

Rechargeable Zn–air batteries (ZABs), with a high theoretical energy density of 1084 W h kg⁻¹, are considered as one of the most promising energy technologies for the emerging flexible and wearable electronics. However, the most challenging issue for ZABs is the sluggish kinetics and unsatisfactory stability for the oxygen reduction reaction/oxygen evolution reaction (ORR/OER) on the air electrode. Herein, a flexible, large-area 3D N-doped graphene-like full carbon air electrode with an O-rich functional group (NO-G@CP) was successfully synthesized using a cotton pad as a template via a scalable, low-cost and one-step pyrolysis process. Benefitting from the 3D porous N-doped graphene structure and rich CO group, the as-prepared NO-G@CP air electrode exhibits superior ORR/OER bifunctional catalytic activity and stability. Impressively, the integrated NO-G@CP can be directly used as an efficient air cathode for flexible solid-state ZABs. An open-circuit voltage of up to 1.328 V and a maximum power density of 65.1 mW cm⁻² for the flexible solid-state ZABs have been obtained. This work provides valuable guidance toward the development of emerging flexible and wearable devices in practice.