Three-dimensional graphene-polyaniline hybrid hollow spheres by layer-by-layer assembly for application in supercapacitor

• A graphene-polyaniline (GR-PANI) hybrid hollow sphere is fabricated by layer-by-layer (LBL) assembly technique.
• The GR-PANI hollow sphere has higher specific capacitance than stacked GR-PANI LBL film.
• 64% of its initial capacitance is maintained with the current density increased from 0.5 to 20 A g−1.
• A high capacity retention rate of 83% after 1000 cycles can be achieved.

A novel kind of three-dimensional graphene-polyaniline hybrid hollow sphere (RGO-PANI HS) has been prepared via layer-by-layer (LBL) assembly of negatively-charged reduced graphene oxide (RGO) and positively charged polyaniline (PANI) on polystyrene (PS) microsphere, followed by the removal of the PS template. The hollow structure of the obtained RGO-PANI HS is confirmed by transmission electron microscopy (TEM). When used as the electrode materials for supercapacitor, the specific capacitance of the RGO-PANI HS reaches 381 F/g at a current density of 4.0 A/g, which is much higher than 251 F/g of the stacked RGO-PANI LBL film. The higher specific capacitance of RGO-PANI HS should be attributed to its unique hollow structure which provides a larger accessible surface area and facilitate the charge and ion transport. In addition, its specific capacitance can be facilely tailored by changing the assembly cycle number. Furthermore, good cycling stability is also demonstrated with 83% of the original capacitance value maintained after 1000 charging/discharging cycles.