Heteroatom-doped hollow carbon microspheres based on amphiphilic supramolecular vesicles and highly crosslinked polyphosphazene for high performance supercapacitor electrode materials

Hybrid hollow polymeric microspheres (HPMSs) are synthesized by encapsulating the supramolecular vesicles with polyphosphazene through a rapid one-step polycondensation reaction. Subsequent carbonization treatments of the HPMSs lead to corresponding hollow carbon microspheres (HCMSs) with well-preserved geometry. The sizes of HPMSs and HCMSs are controlled by the vesicles, which is directly determined by the feeding ratio of the assembly units. Electrodes based on HCMSs showed a specific capacitance of 314.6 F/g at a current density of 0.2 A/g in 6 M KOH electrolyte, 180.0 F/g at a current density of 30 A/g, and high stability of 98.2% of capacity retention after 2000 cycles. Both the high surface area and high heteroatoms level of HCMSs contribute to the excellent capacitive performance. Meanwhile, the hollow carbon structure ensured the satisfactory capacitive performance by increasing utilization efficiency of the surface area as well as achieving short diffusion paths for electrolyte ions.