Journal of Colloid and Interface Science ( IF 9.4 ) Pub Date : 2021-03-09 , DOI: 10.1016/j.jcis.2021.02.112
Misganu Chewaka Fite , Toyoko Imae
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The effect of conductive materials (polyaniline (PA) or carbon dots (Cdots)) added to supercapacitor consisting of nitrogen-doped graphene oxide (NG) and magnetic nanoparticles (magnetite, Fe3O4) was assessed. Small amounts (4 wt%) of Cdots in composites of NG and Fe3O4 nanoparticles have shown better supercapacitor performance than the addition of PA. When the external stimulating force (magnetic field, 8.98 mT) was coupled with the electrochemical system, the specific capacitance was highest (2213 F/g at a scan rate of 5 mV/s) and the cyclic retention was 91% after 5000 cycles for the NG/Cdots/Fe3O4 composite electrode. These reports show that the adequate ternary composite materials effectively enhance the specific capacitance, increase the specific energy density and maintain the durability of supercapacitors under the magnet. The increase in the specific capacitance under the uniform magnetic field was proportional to the 3/5 power of bulk electrolyte concentration, although the power value was different from the theoretical estimation. The complex capacitance was almost double under the magnetic field due to the convection induced by the Lorentz force. It was also confirmed in comparison with the theoretical estimation that the Lorentz effect was responsible for the reduction of the charge transfer resistance, the increase of the relaxation time constant, the facilitation of the ion diffusion, and hence the increase of the double-layer capacitance. The present results will open a new window for the enhancement mechanisms on the capacitance efficiency under the magnetic field.
中文翻译:
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在外部磁场下用聚苯胺或碳点提高氮掺杂氧化石墨烯/磁铁矿的电容:理论估计的支持
评估了添加到超级电容器中的导电材料(聚苯胺(PA)或碳点(Cdot))的效果,该超级电容器由掺氮氧化石墨烯(NG)和磁性纳米颗粒(磁铁矿,Fe 3 O 4)组成。NG和Fe 3 O 4纳米颗粒的复合物中少量的Cdots(4 wt%)已显示出比添加PA更好的超级电容器性能。当外部刺激力(磁场,8.98 mT)与电化学系统耦合时,比电容最高(扫描速度为5 mV / s时为2213 F / g),经过5000次循环后,循环保留率为91%。 NG / Cdots / Fe 3 O 4复合电极。这些报告表明,适当的三元复合材料可有效提高比电容,增加比能量密度并保持磁体下超级电容器的耐久性。尽管功率值与理论估计值不同,但是在均匀磁场下比电容的增加与整体电解质浓度的3/5功率成正比。由于洛伦兹力引起的对流,复电容在磁场下几乎增加了一倍。与理论估计值相比,还可以肯定的是,洛伦兹效应是导致电荷转移电阻降低,弛豫时间常数增加,离子扩散促进的原因。从而增加了双层电容。目前的结果将为磁场下的电容效率增强机制打开一个新的窗口。