Restacked nanohybrid graphene layers with expanded interlayer distance enabled by inorganic spacer for highly efficient, flexible Na-ion battery anodes

Here, we demonstrate a novel synthetic route to prepare restacked nanohybrid graphene layers (NHGLs) with the expanded interlayer distance enabled by incorporating inorganic spacer for the reliable high-capacity sodium-ion battery (NIB) anodes. Nanohybrid graphene oxide flakes (NHGOFs) were obtained through partial complexation of metallic Sn cation with graphene oxides (GOs) exfoliated from graphite. Negatively charged NHGOFs were restacked parallel to Zn substrate through an electrostatic interaction with Zn in an acidic solution. After detachment and freeze-drying step, NHGLs with the expanded interlayer distance of similar to 7.54 angstrom along the c-axis supported by metallic Sn cation spacer were achieved. To clarify the beneficial effect of the expanded interlayer distance, electrochemical performances of NHGLs anode were investigated. Finally, a flexible feature of restacked NHGLs anode was presented during a simple bending test using a pouch-type cell.