Lin Yang,Jingxian Wang,Anchang Li,Honghai Liu,Ming Zhang,Zhongrong Shen
Porous carbon has attracted great interest as an anode for lithium-ion capacitors (LICs) due to its high lithium-ion storage capacity. However, its low electrical conductivity and tap density are major challenges facing its commercialization. In this study, a low-cost Fe3C@N-doped C material has been synthesized via the polymerization and carbonization of the natural biomass material sodium alginate (SA) and commercial p-Phenylenediamine (PPD). FeCl3 is used as both a crosslinking agent and catalyst to promote the PPD oxidation reaction and the degree of carbonization. The as-obtained graphite-like Fe3C@N-doped C with a carbonization treatment at 700 °C exhibits both high Fe and N contents of 3.93 wt% and 5.34 wt%, respectively, and a high electrical conductivity equivalent to graphite, which would be favorable for lithium-ion storage due to the synergistic effect of the high electrical conductivity and pseudocapacitive characteristics. Moreover, the Fe3C@N-doped C exhibits a superior lithium-ion storage capacity of 566.0 mA h g−1, higher than that of commercial graphite, and a high tap density of 0.59 g cm−3. As the negative electrode for an LIC, the capacitor delivers a high specific energy of 86.6 W h kg−1 at a current density of 0.1 A g−1. Meanwhile, good cyclability has also been achieved for the cell. The superior electrochemical properties of the LICs could be attributed to the high lithium-ion storage capacity and good cycling stability of the Fe3C@N-doped C material.
Rundong Guo,Dong Su,Fu Chen,Yongzhi Cheng,Xian Wang,Rongzhou Gong,Hui Luo
Microwave-absorbing materials have attracted enormous attention for electromagnetic (EM) pollution. Herein, hollow beaded Fe3C/N-doped carbon fibers (Fe3C/NCFs) were synthesized through convenient electrospinning and subsequent thermal treatment. The special hollow morphology of the samples is conducive to achieve lightweight and broadband microwave absorption properties. The thermal treatment temperatures exhibit a significant impact on conductivity and EM properties. The broadest effective absorption bandwidth (EAB) is 5.28 GHz at 2.16 mm when the thermal treatment temperature is 700 °C, and the EAB can cover 13.13 GHz with a tunable absorber thickness from 1.0 to 3.5 mm when the thermal treatment temperature is 750 °C. The excellent microwave absorption properties of the samples are due to the synergistic effect of impedance matching and strong EM energy attenuation abilities. Hence, the magnetic hollow beaded Fe3C/NCFs are expected to be an attractive candidate material as a lightweight and efficient microwave absorber in the future.
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