3D Printing of Hierarchical Graphene Lattice for Advanced Na Metal Anodes

The expanding energy storage market has created a surge of interest in the exploration of high energy density alternatives to Li-ion batteries, and Na metal batteries have received considerable attention due to their abundant reserves and low cost. Similar to Li metal anodes, the unstable plating/stripping behaviors of Na metal anodes upon cycling hinder their practical applications at room temperature. Herein, a superelastic graphene lattice (GL) with hierarchical structures was fabricated via a 3D printing technique on the basis of the direct inkjet writing strategy. This approach enables the precise tailoring of the multiscale graphene bulk structure, from nanometer GO building elements to macroscopic monoliths. Due to the pore-structure design of the GL, the rim regions of the holes demonstrated a highly concentrated current density and could serve as preferred sites for Na deposition. This phenomenon was utilized to regulate the Na deposition; hence, a stable Na metal anode is produced. As a result, a high Coulombic efficiency of 99.84% was realized for a long lifetime of 500 cycles (∼1000 h) at a current density of 1 mA cm–2. These results provide a novel insight into the rational design of graphene-based material structures at multiscale for high-performance Na metal anodes.