Three-dimensional porous carbon nanofibers scaffold to homogenize sodium deposition for dendrite-free sodium metal batteries

Abstract

Sodium metal anode possesses the advantages of high specific capacity and low redox potential, yet poses safety concerns due to the formation of dendrites during operation. Herein, a three-dimensional porous carbon nanofiber (CNF) scaffold was constructed on the surface of commercial Al foil using chemical vapor deposition. During the chemical vapor deposition process, the uneven diffusion rate of carbon atoms within catalyst particles is determined by preferential deposition on specific crystal planes, leading to the formation of pores on the surface of CNF. The abundant mesopores on the surface of CNF and the three-dimensional scaffold structure can disperse the local current density, provide sufficient ion diffusion pathways, and effectively regulate the deposition behavior of Na metal. Consequently, the CNF/Al electrode operated for 300 cycles with an average Coulombic efficiency of 99.7% at 1 mA cm⁻² and 1 mAh cm⁻². The symmetric cell was demonstrated to remain operational for over 600 h at 1 mA cm⁻² and 1 mAh cm⁻². Additionally, the CNF/Al || NVP-C full cell also exhibited excellent Coulombic efficiency and cycling stability. This straightforward and scalable approach offers promising prospects for the extensive application of sodium metal anodes.