Luo HeMing,Yang YanFei,Chen YanZheng,Zhang JianQiang,Zhao Xia
This paper presents the direct synthesis of highly porous carbons via the carbonization of potassium humate in inert atmosphere without any activation. Carbonization temperature is important for carbon structures and their electrochemical performance in electric double-layer capacitors. The CK800 material derived from potassium humate has a high–specific surface area of 890 m 2 g −1 and an ideal average pore size of 2.56 nm. The CK800 material can also deliver a high-specific capacitance of 232 F g −1 (26.1 µF cm −2 ) at a constant charge/discharge current of 0.5 A g −1 . This capacitance is maintained at a value of 114 F g −1 (12.8 µF cm −2 ) at 30 A g −1 . This material also has good cycle stability with over 93.5 % capacitance retention after 5000 cycles when measured in a three-electrode system using 6 M KOH as electrolyte. In this study, the CK800 material is tested in a three-electrode system using 1 M NaHCO 3 as electrolyte. Operational voltage in 1 M NaHCO 3 aqueous solution could be extended up to 1.3 V.
Yanfang Song,Jinxiong Wu,Jiliang Zheng,Yiwei Sun,Andrei Ivanets,Guangming Du,Xintai Su
The doping of multiple heteroatoms can improve the electrochemical properties of carbon substrates. However, in existing studies, carbon, iron and nitrogen sources are generally mixed directly and then pyrolyzed for secondary activation. This tends to form aggregates of metal particles or metal oxides and requires the consumption of large amounts of alkali and energy. Therefore, there is an urgent need to develop an environmentally friendly technology capable of uniformly doping iron and nitrogen into carbon materials. In this work, porous Fe–N–C composites were prepared at 600 °C using potassium humate (HA-K) obtained from cotton straw by low-temperature pyrolysis as the carbon source, and urea-iron complexes formed by the pre-coordination of urea and Fe as the iron and nitrogen sources. In the absence of secondary activation, the best sample Fe-NHPC-2 had a good mesoporous structure with high specific surface area (889. 01 m2 g−1). It had a high specific capacitance of 256.8 F g−1 at a current density of 0.5 A g−1. The capacitance retention was 92.6% after 10,000 cycles at a current density of 10 A g−1. In the symmetric supercapacitor application, the energy density reached 33.16 Wh kg−1 when the power density was 600.2 W kg−1.
危险品化学品经营许可证（带存储）