An ordered mesoporous carbon nanosphere-encapsulated graphene network with optimized nitrogen doping for enhanced supercapacitor performanceElectronic supplementary information (ESI) available. See DOI: 10.1039/c8nr04194f

Developing a simple strategy to simultaneously overcome the aggregation of graphene nanosheets and endow the ordered mesoporous carbon with the high conductivity required for a practical supercapacitor remains a great challenge. Herein, a strategy involving ethanol dispersive mixing, followed by co-carbonization was developed to prepare a N-doped ordered mesoporous carbon nanosphere-encapsulated graphene network (N-OMCN@GN), where the ordered mesoporous carbon nanosphere (OMCN) was inserted into the interlayers of graphene nanosheets and an optimized nitrogen doping level of up to 11.7 at% was simultaneously achieved. The as-prepared N-OMCN@GN possesses hierarchically porous architectures with largely accessible surfaces, short ion access/diffusion length with fast ion transfer, and a sphere (electron reservoir)-encapsulated plane (electron highway) configuration for convenient electron transfer. As a result, the N-OMCN@GN supercapacitor exhibited a high specific capacitance of 242.3 F g −1 at 1 A g −1 and excellent cycling stability with a capacitance retention of 95% at 5 A g −1 after 10 000 cycles. This study would pave the way to excavate the synergistic effects of graphene and OMCN for energy storage applications. A N-doped ordered mesoporous carbon nanosphere-encapsulated graphene network can serve as a synergetic electron reservoir and electron highway for a supercapacitor.