Kaiqiang Qin

N-Doped Porous Carbon Nanofibers/Porous Silver Network Hybrid for High-Rate Supercapacitor Electrode

A three-dimensional cross-linked porous silver network (PSN) is fabricated by silver mirror reaction using polymer foam as the template. The N-doped porous carbon nanofibers (N-PCNFs) are further prepared on PSN by chemical vapor deposition and treated by ammonia gas subsequently. The PSN substrate serving as the inner current collector will improve the electron transport efficiency significantly. The ammonia gas can not only introduce nitrogen doping into PCNFs but also increase the specific surface area of PCNFs at the same time. Because of its large surface area (801 m2/g), high electrical conductivity (211 S/cm), and robust structure, the as-constructed N-PCNFs/PSN demonstrates a specific capacitance of 222 F/g at the current density of 100 A/g with a superior rate capability of 90.8% of its initial capacitance ranging from 1 to 100 A/g while applied as the supercapacitor electrode. The symmetric supercapacitor device based on N-PCNFs/PSN displays an energy density of 8.5 W h/kg with power density of 250 W/kg and excellent cycling stability, which attains 103% capacitance retention after 10 000 charge-discharge cycles at a high current density of 20 A/g, which indicates that N-PCNFs/PSN is a promising candidate for supercapacitor electrode materials.

Nitrogen and oxygen co-doped 3D nanoporous duct-like graphene@carbon nano-cage hybrid films for high-performance multi-style supercapacitors

Interconnected 3D graphene foams with a large number of controllable micro–mesoporous structures are promising electrode materials for supercapacitors due to their high electrical conductivity and large effective surface area. Here we successfully obtained a flexible high-quality nitrogen and oxygen co-doped 3D nanoporous duct-like graphene@carbon nano-cage film by chemical vapor deposition using nanoporous copper (NPC) as the substrate and further modifying with HNO3. The bicontinuous mesoporous architecture catalyzed by NPC retains the 2D coherent electronic properties of graphene. Carbon nano-cages grown on the surface of the 3D nanoporous graphene combined with the microporous structure caused by heteroatom-doping greatly increase the effective specific surface area. Moreover, heteroatom-doping and oxygen-containing groups on the surface of graphene can obtain extra redox capacitance and achieve good wettability between the electrode and the electrolyte. The superior structure means that NO-3DG@CNC-based multi-style supercapacitors, such as aqueous-system, ionic-system, and lithium-ion capacitors etc., all show high energy density, high power density and excellent cycling stability.