Highly graphitic nitrogen-doped carbon nano-onions (N-CNO) have attracted much attention in the field of energy storage device applications. Herein, we have synthesized N-CNO by a simple flame pyrolysis method for symmetric and asymmetric (ASC) supercapacitor devices. The nitrogen doping is performed in-situ during the pyrolysis of pyrrole. The synthesized N-CNO has a high surface area of 49 m² g⁻¹ with 4 at% nitrogen content. The structural properties have confirmed the formation of graphitic N-CNO with highly ordered concentric graphene layers with proper lattice spacing. The fabricated symmetric and asymmetric devices have shown high specific capacitance and excellent energy-power performance. Especially, the ASC device shows a specific capacitance value 205 F g⁻¹ with a high energy density (60 Wh kg⁻¹) and power density (5.5 kW kg⁻¹), leading to an increase in the power density by 260% for a mere 60% decrease in the energy density. In addition, both the novel symmetric and asymmetric devices have shown excellent capacity retention of 96% to 98% over 5000 cycles. The demonstrated results show the superior electrochemical performance of the active material, which indicates that the N-rich-CNOs can be used as a novel anode material in energy storage devices with high energy density and high power performance.

中文翻译：

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N掺杂碳纳米洋葱基非对称和对称超级电容器器件的优越能量-功率性能

高度石墨化的氮掺杂碳纳米洋葱（N-CNO）在储能器件应用领域备受关注。在此，我们通过简单的火焰热解方法合成了用于对称和非对称 (ASC) 超级电容器器件的 N-CNO。在吡咯的热解过程中原位进行氮掺杂。^{合成的 N-CNO 具有 49 m 2} g ^-1的高表面积和 4 at% 的氮含量。结构特性证实了石墨N-CNO的形成，具有高度有序的同心石墨烯层，具有适当的晶格间距。制造的对称和非对称器件显示出高比电容和优异的能量-功率性能。特别是，ASC 器件的比电容值为 205 F g ^-1具有高能量密度（60 Wh kg ^-1）和功率密度（5.5 kW kg ^-1），导致功率密度增加260%，而能量密度仅降低60%。此外，新型对称和非对称器件在 5000 次循环中均表现出 96% 至 98% 的出色容量保持率。结果表明，该活性材料具有优异的电化学性能，这表明富氮-CNOs可用作具有高能量密度和高功率性能的储能装置中的新型负极材料。