Hollow Carbon Nanospheres with Developed Porous Structure and Retained N Doping for Facilitated Electrochemical Energy Storage

Development of highly porous carbons with abundant surface functionalities and well-defined nanostructure is of significance for many important electrochemical energy storage systems. However, porous carbons suffer from a compromise between porosity, doped functionality, and nanostructure that have thus far restricted their performances. Here, we report the design of highly porous, nitrogen-enriched hollow carbon nanospheres (PN-HCNs) by an interfacial copolymerization strategy followed by NH 3 -assisted carbonization, and further demonstrate their significance and effectiveness in enhancing the electrochemical performances. The PN-HCN simultaneously delivers a large surface area (1237 m 2 g –1 ) and high N functionalities (6.25 atom %) with a remarkable efficiency of the surface area increase to N loss ratio enabled by NH 3 treatment while inheriting the hollow nanospherical structure. Accordingly, owing to the enhanced surface area and retained N doping, the prepared PN-HCN demonstrates outstanding electrochemical performances as a cathode host in lithium–sulfur batteries, including a near-to-theoretical capacity of 1620 mAh g –1, high rate capability and good cycling stability (789 mAh g –1 at 0.5C after 200 cycles). These results are superior to those of HCN without NH 3 treatment. Also, PN-HCN exhibits superior capacitances (203 F g –1 ) and fast ion transport ability in supercapacitors. Our finding shows the simultaneous achievement of both highly porous structures and sufficient N functionalities for high-performance applications.