A simple and effective host for sodium metal anode : a 3D-printed high pyrrolic-N doped graphene microlattice aerogel

Rechargeable sodium metal batteries are promising candidates for next-generation low-cost rechargeable batteries by virtue of the abundance and low cost of Na resources. However, safety issues caused by uncontrollable Na dendrites prevent its further development. Herein, we developed a three-dimensional (3D) printed nitrogen doped graphene aerogel (3DP-NGA) microlattice host to regulate uniform Na nucleation and deposition. Density functional theory (DFT) calculation results indicate that the sodiophilic sites mainly originate from pyrrolic-N defects, which can be easily created and controlled by plasma treatment. With the designed architecture and N doping-induced sodiophilic surface, the 3DP-NGA microlattice can effectively guide sodium ion flux and deposition as well as decrease the nucleation energy barrier and provide abundant nucleation sites, leading to the homogeneous deposition of Na without dendrite formation, as demonstrated by in situ optical microscopy characterization. Encouragingly, the 3DP-NGA microlattice delivers low nucleation overpotentials (9.9 and 14.8 mV at 0.5 and 1.0 mA cm⁻², respectively) and an ultralong cycle-life over 2000 h (3000 cycles) with an average coulombic efficiency of 99.90% at a high current density of 3.0 mA cm⁻² with 1.0 mA h cm⁻². Moreover, at a high Na loading of 10.0 mA h cm⁻² (747.6 mA h g⁻¹), the electrode can cycle stably over 500 h. Finally, a 3D-printed full battery consisting of Na@3DP-NGA anode and 3D-printed Na₃V₂(PO₄)₃C-rGO (3DP-NVP@C-rGO) cathode was assembled and delivered a capacity of 85.3 mA h g⁻¹ at 100.0 mA g⁻¹ after 1000 cycles.