Abstract
A thermodynamically and kinetically stable 3D hierarchical carbonaceous nanostructure is constructed to examine its potential as an anode for sodium-ion batteries (SIBs). Heptagonal and quadrilateral staggered carbon rings are formed where the graphite layers and the CNT interconnect vertically. Based on first-principles calculations, such a graphite-CNT hybrid with expanded interlayer spacing allows effective binding to Na atoms and contributes a high specific capacity of 324.3 mAh g(-1). It maintains a great electronic conductivity for both pristine and Na-adsorbed graphite-CNT along the expanded graphite layers, and constructs a 3D electronic transport network when a large number of Na atoms are adsorbed. This hierarchical nanostructure predicts a fast inner 3D Na-ion transport network, with energy barriers of 0.56 and 0.50 eV along the expanded graphite layer and the CNT channel, respectively. This research manifests the feasibility of obtaining well-performed graphite-based anodes for SIBs through purposeful microcosmic morphology modification.