N-Doped Yolk-Shell Carbon Nanospheres with Carbon Bridges for Supercapacitors

N-dopingmultilocular carbon spheres are beneficial toimprovingthe electrical property due to their unique pore structure and elementalcomposition; nevertheless, there is a great challenge to fabricatethis structure in a facile way. In this work, an N-doping yolk-shellcarbon nanosphere with a carbon bridges structurewas prepared by domain-limited carbonization of RF@SiO2 (RF = resorcinol-formaldehyde resin) with ethylenediamine (EDA)as the nitrogen precursor. The structure of the carbon bridgesand the carbon shell's thickness can be adjusted by controllingthe thickness of the silica layer, resulting in a change in morphology(from dense nanospheres to yolk-shell nanospheres). The optimizedyolk-shell carbon nanospheres (C@C-2 nanospheres) exhibitedhigh N-doping, an abundant micro-mesoporous structure, and an optimumcarbon bridges structure, contributing to a high-ratecapability in a supercapacitor, which was reflected in the energystorage dynamics. Herein, C@C-2 nanospheres, as an electrode materialfor supercapacitors, presented a reversible specific capacitance of373.3 F g(-1) at 0.5 A g(-1) in 2M KOH and retained a well-advanced capacitance retention capability(95.8%) at 4 A g(-1) for more than 10,000 cycles.This work sheds light on an avenue to design high-performance porouscarbons for efficient energy storage.

Automated summary

N-doping yolk-shell carbon nanospheres with carbon bridges structure were prepared by domain-limited carbonization. The optimized carbon nanospheres exhibited high N-doping and an abundant micro-mesoporous structure, resulting in a high-rate capability in a supercapacitor. This work provides insights into the design of high-performance porous carbons for efficient energy storage.