Micropore‐Rich Yolk‐Shell N‐doped Carbon Spheres: An Ideal Electrode Material for High‐Energy Capacitive Energy Storage

Abstract Increasing the energy density of electrochemical double layer capacitors (EDLCs) can broaden their applications in energy storage but remains a formidable challenge. Herein, micropore‐rich yolk‐shell structured N‐doped carbon spheres (YSNCSs) were constructed by a one‐pot surfactant‐free self‐assembly method in aqueous solution. The resultant YSNCSs after activation possessed an ultrahigh surface area of 2536 m 2 g −1 , among which 80 % was contributed from micropores. When applied in EDLCs, the activated YSNCSs demonstrated an unprecedentedly high capacitance (270 F g −1 at 1 A g −1 ) in 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF 4 ]) ionic liquid, affording an ultrahigh energy density (133 Wh kg −1 at 943 W kg −1 ). The present contribution provides insight into engineering porous carbons for capacitive energy storage.