Nitrogen-doped ordered mesoporous carbon using task-specific ionic liquid as a dopant for high-performance supercapacito
- PDF / 711,704 Bytes
- 10 Pages / 584.957 x 782.986 pts Page_size
- 89 Downloads / 150 Views
Ordered mesoporous carbons (OMCs) are appealing alternatives to conventional porous activated carbon applied to electronic energy storage and conversion devices. Nitrogen-doped OMC (NOMC) was prepared with a soft-template strategy directly using task-specific ionic liquid with dicyanamide anion as the nitrogen dopant, and utilized as supercapacitors for the first time. Compared with pristine OMC, NOMC showed excellent electrochemical capacitive behavior in 6 M KOH electrolyte. NOMC possessed a high specific capacitance of 427 F/g at a current density of 1 A/g and exhibited a stable cycle life (almost 98% retained at a current density of 5 A/g after 2000 cycles). The outstanding capacitive performance of NOMC was ascribed to the synergetic effects of its bimodal mesoporous structure, large specific surface area (1919 m2/g), and nitrogen doping (3.52 wt%), which help to accelerate the ion diffusion, increase the surface charge storage, and intensify pseudo-capacitive reactions.
I. INTRODUCTION
Researchers across the globe are currently facing the challenge of developing environmentally friendly, sustainable, and low-cost energy resources. Supercapacitors are an emerging type of electrochemical energy source for storage and conversion devices, because of their high power density and long cycle life.1 Especially promising are carbon-based supercapacitors; these have attracted much attention because of their light weight, rapid charging, and discharging rates, and bipolar operational flexibility.2 Porous carbon materials are most commonly used as electrode materials for electrical double-layer capacitance (EDLC).3 Ions diffuse and accumulate in the double electrical layer formed along the interface between the electrolyte and the electrode; this wide double layer is attainable because of the large surface area and free pore channels of the electrode material. Another type of electrochemical energy storage device is known as a pseudocapacitance; it relies on the reversible faradaic redox reactions of electroactive species on the electrode surface.1,4 Ordered mesoporous carbons (OMCs) are popular carbonaceous materials widely applied in adsorption, electrochemistry, and catalysis because of their unique tunable highly ordered mesoporous framework, large surface area and pore volume, and mechanical stability.5 They are ideal alternatives to conventional porous activated carbon as potential electrode materials for Contributing Editor: Sung-Yoon Chung a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.473
supercapacitors in electronic devices.6,7 Uniform mesoporous channels can shorten the distance for ion diffusion, accelerate the electrolyte diffusion, and alleviate pore blockage, because ions accumulate in the micropores.8 However, only a small number of active sites on the surface of OMCs can be used for electrostatic adsorption of electrolyte ions, because of the OMCs’ high hydrophobicity. Consequently, the incorporation of heteroatoms—such as nitrogen, boron, and sulfur—onto the car
Data Loading...
