Enhanced Structural Stability and Volumetric Capacity of a 3D Pyknotic Graphene Conductive Network via a Pillar Effect of Sn Nanoparticles for Sodium-Ion Batteries.

High volumetric capacity and durability anode materials for sodium ion batteries have been urgently required for practical applications. Herein, we reported a Sn-pillared pyknotic graphene conductive network with high-level N-doping. This densely stacked block offers high volumetric Na-ion storage capacity, rapid electrochemical reaction kinetics, and robust structural stability during cycling owing to the high capacity component (metallic Sn ≈847 mAh g -1 ), high tap density (≈2.63 g cm -3 ), high conductivity (N doping ≈5 at. %), and strong spatially confined and pillared structure. Moreover, theoretical simulations have indicated that the charge accumulation around the N-doped region is more pronounced compared to the pristine one, and electrons accumulate around the N atom while loss occurs at the Na atom. These studies also suggest that it might possibly contribute to higher conductivity and stronger electrophilic reactivity, thereby resulting in enhanced Na-ion storage performance. As a result, the as-obtained electrode material exhibits competitive volumetric capacity (1462 mAh cm -3 at 0.1 A g -1 ), cycling performance (1207 mAh cm -3 after 100 cycles), and promising rate behavior simultaneously.