Boosting Supercapacitor Performance of Graphene by Coupling with Nitrogen‐Doped Hollow Carbon Frameworks

Abstract

Graphene as a suitable electrode has been extensively used for electrochemical double‐layer capacitors based on its excellent properties, including high electrical conductivity and large specific surface area. However, one of the drawbacks is the unavoidable stacking tendency between the graphene nanosheets, resulting in limited electrochemically specific surface area. Herein, novel graphene nanosheets supported by hollow nitrogen‐doped carbon frameworks derived from ZIF‐8 (GPNC) were fabricated through a simple polyethyleneimine (PEI)‐assisted pyrolysis strategy, to boost capacitance performance. Benefiting from the unique scaffold/support role of hollow nitrogen‐doped carbon frameworks within the graphene interlayer, the GPNC with a large specific surface area, along with ample micropore/mesopore channels and high nitrogen content, is capable of facilitating electron and electrolyte ion migration kinetics and enhancing intrinsic electrochemical activity. Thus, the GPNC exhibits the highest charge storage of 218 F g−1 and superior rate capability of 74 % when the current density increased from 0.5 to 20 Ag−1 in comparison to pristine graphene and common ZIF‐derived carbon/graphene electrodes. The assembled GPNC//GPNC two‐electrode system further delivers a maximum power of 9080 Wkg−1 with outstanding electrochemical retention of 84 % over 10 000 cycles.

Fabrication of Porous Carbon Nanosheets with the Engineered Graphitic Structure for Electrochemical Supercapacitors

“…This can be further confirmed by the Raman spectra of the samples. As shown in Figure b, the two distinctive peaks placed at around 1330 and 1590 cm –1 belong to the disordered D band and sp 2 -bonded/graphitic G band of carbon materials, respectively . The intensity ratio ( I D / I G ) of the D band and G band for PCNS was calculated to be 0.94, which is lower than that of PC of 1.0, suggesting the presence of more graphitization or an sp 2 -hybridized structure within the PCNS frameworks.…”

“…Cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) technologies, and electrochemical impedance spectra (EIS) at the open circuit potential with a 5 mV amplitude under a frequency range of 100 kHz–10 mHz were employed to evaluate the charge storage behavior, specific capacitance, and electron/ion transport kinetics of samples, respectively. The preparation process of the electrode and test conditions as well as the calculation method of specific capacitance were similar to our previous studies, , and the details are presented in the Supporting Information.…”

Nature‐inspired porous multichannel carbon monolith: Molecular cooperative enables sustainable production and high‐performance capacitive energy storage

“…41,59,61,[63][64][65][66] It also owns comparable or even better gravimetric density than other thick carbon electrode-based SCs. 59,63,[67][68][69][70][71][72][73] Figure 7(C) further compares the device thickness, areal and gravimetric capacitances of N-PCM-9-based quasi-solid-state SC with other thick-electrodebased SCs. 41,59,60,[63][64][65][74][75][76][77] Considering they are correlating factors, comprehensively, our N-PCM-9-based SC shows compatible device thickness, gravimetric capacitance, and much better areal capacitance than others.…”

Synthesis and Supercapacitor Performance of Histidine-functionalized Carbon Dots/Graphene Aerogel

“…为进一步研究 His-CDs/GA-2 复合电极材料的实 际应用，将 His-CDs/GA-2 组装成对称超级电容器 (His-CDs/GA-2//His-CDs/GA-2)，在两电极体系下测 试。图 S7(a)为该对称电容器在电压窗口为 0~1 V， 扫描速率 5~100 mV• s -1 下的 CV 曲线。由图可见，在 高扫描速率 100 mV• s -1 下，CV 曲线的形状仅出现轻 微的偏斜， 表明其具有良好的电荷传输能力。 图 S7(b) 为 His-CDs/GA-2//His-CDs/GA-2 在不同电流密度下 的 GCD 曲线。由图可见，所有 GCD 曲线均呈现良 好的对称性，且未出现明显的电压降。图 S8 为 His-CDs/GA-2//His-CDs/GA-2 的循环性能图。 该对称 电容器在 5 A• g -1 下，循环充放电 20000 次，比电容 保持率为 88.4%。His-CDs/GA-2//His-CDs/GA-2 良好 的循环保持率主要得益于其独特的三维多孔结构有 效缓解了充放电过程中体积的膨胀和收缩。基于 GCD 曲线，由公式(S2~S4)计算对称电容器的能量密 度和功率密度，结果如图 8 所示。该装置在功率密 度为 250 W/kg 时，能量密度达到 10.14 Wh/kg，且在 功率密度增加到 10 kW/kg 时，能量密度仍能保持 6.43 Wh/kg。此外，His-CDs/GA-2//His-CDs/GA-2 最 大能量密度高于先前文献所报道的石墨烯基对称电 容器 [2,5,[13][14][24][25] 。 图 8 His-CDs/GA-2//His-CDs/GA-2 的拉贡图…”