N-doped hierarchical porous hollow carbon spheres with multi-cavities for high performance Na-ion storage

Sodium ion hybrid capacitors (SIHC) have attracted extensive interest owing to their both high energy and power densities as well as long cycle life. Herein, a novel dual-carbon SIHC is assembled with hierarchical porous hollow multicavity carbon spheres (HMCSs) as an intercalated anode and activated HMCSs (AHMCSs) as a capacitive cathode. The HMCSs are prepared from aniline and pyrrole through a one-step carbonization with F-127 as soft template, and show high reversible capacity and good rate performance as anode for sodium ion battery. And AHMCSs delivers high energy densities of 16.6 and 12.2 Wh kg−1 at the power densities of 250.1 and 9996.4 W kg−1 benefiting from their high surface area and hierarchical porous structure after confined KOH activation. The combination of HMCSs anode and AHMCSs cathode endows the SIHC superior energy densities of 140.1 and 87.1 Wh kg−1 under the power densities of 380.0 and 14249.7 W kg−1, and 80.8% capacitance retention after 4400 cycles at 1 A g−1. Our work provides a new approach for developing high performance sodium storage devices.