Foldable and scrollable graphene paper with tuned interlayer spacing as high areal capacity anodes for sodium-ion batteries

Bulk graphitic carbon materials with expanded interlayer spacing and abundant defects may serve as efficient anodes with high areal capacities for sodium-ion batteries (SIBs). However, obtaining long-range order in bulk graphitic carbon materials with expanded interlayer spacing is extremely difficult. Herein, an explosive decom-position method is demonstrated to realize thermally reduced graphene oxide (rGO) paper with tuned interlayer spacing. The in-situ temperature-dependent X-ray diffraction (td-XRD) was utilized to establish the correlation between heating rate and interlayer spacing. Based on td-XRD results, free-standing graphene paper (FSG) was synthesized at 450 degrees C under a high heating rate of 70 degrees C/min. The FSG exhibits a highly porous structure made of graphene flakes with abundant surface epoxy groups with an overall interlayer spacing of 0.38-0.39 nm. The rGO flakes in FSG are separated by large voids that provide fast mass transport pathways and allow expan-sion/contraction of crystallites upon reversible Na intercalation. The FSG was utilized directly as anodes without any binder and conductive agent and delivered an excellent reversible capacity of 290 mAh/g at a current density of 50 mA/g. Moreover, the FSG exhibited excellent foldability and rollability to create high areal density anodes, delivering an areal capacity of 0.62 mAh/cm(2) at a current density of 100 mu A/cm(2). These results open the door to fabricate graphene material-based carbon anodes with tunable interlayer spacing for high-performance SIBs.

Automated summary

The explosive decomposition method demonstrated in this study allows for the realization of thermally reduced graphene oxide paper with tunable interlayer spacing, providing potential for high-performance sodium-ion battery anodes.