High volumetric supercapacitor with a long life span based on polymer dots and graphene sheets

Wei, Ji‐Shi; Chen, Jie; Ding, Hui; Zhang, Peng; Yong-gang, Wang

doi:10.1016/j.jpowsour.2017.08.002

Cited by 26 publications

(18 citation statements)

References 26 publications

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“…However, this idea brings a new challenge because the desired groups with abundant electrons (like phosphate groups) are usually difficult to be modified on the carbon materials. In order to resolve this problem, we used carbon dots (CDs, sub‐10 nm) with desired groups as the guest, and the commercial polyacrylamide (PAM) hydrogel as the host. After calcination on the host–guest composites, we obtained new carbon frameworks which have abundant electron‐rich regions, large surface areas, and appropriate porous structures in the meantime.…”

Section: Methodsmentioning

confidence: 99%

“…Since the large electron‐rich regions of NPOCD/HPC can accelerate cations transfer between the solutions and the interfaces, NPOCD/HPC shows a fast adsorption kinetics with a retention rate over 80% at high current densities (Figure H), which is obviously better than Free‐HPC. To interpret the effects of mass loading, Figure I and Figure S17 in the Supporting Information shows that mass loading of NPOCD/HPC is increased by 10 times, the retention rates of specific capacitance are still above 80% in different electrolytes, which are superior to many similar carbon materials …”

Section: Methodsmentioning

confidence: 99%

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Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High‐Performance Hybrid Supercapacitors

et al. 2018

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3-5 folds or more amounts of carbon materials are required to fill the capacitance gap between the positive/negative electrodes, which finally restrict the whole energy densities of the devices. To improve electrochemical capacitances of carbon materials, three main strategies have been investigated thoroughly: enlarging specific surface areas, [19] constructing porous structures, [20,21] and introducing pseudocapacitive reactions. [22] But each strategy is not perfect. When the surface areas and the pore volumes are improved, the tap densities of electrodes will be reduced. Moreover, enhancing pseudocapacitance by modifying too many functional groups will decrease the whole conductivity and stability of electrode materials. [23] In the present work, we suggest a new concept of building electron-rich regions on the electrode surface, so as to adsorb more cations and accelerate the charge transfer. As a result, the capacitance of carbon materials will be increased reasonably without sacrificing the density, conductivity, and stability of the whole electrode. However, this idea brings a new challenge because the desired groups with abundant electrons (like phosphate groups) are usually difficult to be modified on the carbon materials. In order to resolve this problem, we used carbon dots (CDs, sub-10 nm) [24,25] with desired groups as the guest, and the commercial polyacrylamide (PAM) hydrogel as the host. After calcination on the host-guest composites, we obtained new carbon frameworks which have abundant electron-rich regions, large surface areas, and appropriate porous structures in the meantime. The optimal sample exhibits a specific capacitance up to 468, 510, and 438 F g −1 in alkaline, acidic, and neutral electrolytes, respectively. When it is fabricated into a hybrid supercapacitors with the positive electrode material Ni(OH) 2 /CNTs using an alkaline electrolyte, the mass ratio of positive/negative electrodes is less than 2, an energy density over 90 Wh kg −1 is realized successfully, and 100% of capacity retention rate is recorded after 10 000 cycles. This material also shows excellent performances in both acidic (PbO 2 as positive electrode) and neutral (LiMn 2 O 4 as positive electrode) systems. Detailed structural characterizations and theoretical calculations prove that the well-preserved phosphate/nitrogen groups from the CDs precursors can effectively modulate the electronic structure and form electron-rich regions on the electrode Hybrid supercapacitors generally show high power and long life spans but inferior energy densities, which are mainly caused by carbon negative electrodes with low specific capacitances. To improve the energy densities, the traditional methods include optimizing pore structures and modifying pseudocapacitive groups on the carbon materials. Here, another promising way is suggested, which has no adverse effects to the carbon materials, that is, constructing electron-rich regions on the electrode surfaces for absorbing cations as much as possible. For this aim, a series of hi...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High‐Performance Hybrid Supercapacitors

et al. 2018

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“…Moreover, even at a power density of 7300 W kg –1 , the device still can release an energy density of 3.75 Wh kg –1 (as shown in Figure C). These above obtained results are superior to a great number of reported CDs based EDLCs materials, like the CDs (polymer dots)/Graphene Oxides composite (5.7 Wh kg –1 or 8 Wh L –1 ) and other EDLC devices under similar conditions.…”

Section: Resultsmentioning

confidence: 54%

“…XRD (X-ray diffraction) was carried to detect crystal structures of all samples. From Figure C, broad diffraction peaks with 2θ values of 43° (101 plane) suggest disordered structures of these samples . Similarly, Raman spectra (Figure D) of the three samples include two prominent peaks at approximately 1583 cm –1 (G band) and 1335 cm –1 (D band) .…”

Section: Resultsmentioning

confidence: 77%

“…From Figure 2C, broad diffraction peaks with 2θ values of 43°(101 plane) suggest disordered structures of these samples. 22 Similarly, Raman spectra (Figure 2D) of the three samples include two prominent peaks at approximately 1583 cm −1 (G band) and 1335 cm −1 (D band). 23 The related values of I D /I G increase with temperature (from 0.96 to 1 to 1.02, Table S1, SI), implying the higher disorder degree.…”

Section: Resultsmentioning

confidence: 83%

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Integrated Carbon Dots-Matrix Structures: An Efficient Strategy for High-Performance Electric Double Layer Capacitors

Yang

Zhang

et al. 2020

ACS Appl. Energy Mater.

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As a type of nanomaterials that has received much attention, carbon dots (CDs) have played distinctive roles in various energy storage materials, benefiting from their advantages of controllable surface structures, good solubility, stable chemical properties, and low cost. However, noncontinuous structures of CDs will hinder their further application due to their unsatisfactory charge transfer performance. Here, we develop a series of carbon materials with CDs-carbon matrix structure based on mixed biogels and through a facile calcination−activation method. The potential applications of theses carbon materials have been demonstrated by electric double layer capacitors (EDLCs), where the optimal sample shows 500 F g −1 (1 A g −1 ) and the maximum rate of increment will be over 73% compared with that of an Agglomerated-CDs sample.

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A review of carbon dots and their composite materials for electrochemical energy technologies

et al. 2021

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Carbon dots (CDs) and their composites as energy storage materials and electrocatalysts have emerged as new types of quasi‐zero‐dimensional carbon materials. CDs can provide a large specific surface area, numerous electron–electron hole pairs, adjustable heteroatom doping, rich surface functional groups, and so on. However, the roles and functional mechanisms of CDs and their composite materials in the enhancement of electrochemical performance remain unclear and need to be understood in depth. Based on the most recent literature, this paper comprehensively reviews the synthesis methods and applications of various categories of CDs and their composites as electrode materials of supercapacitors, lithium‐ion batteries, sodium‐ion batteries, and potassium‐ion batteries, and as electrocatalysts for hydrogen evolution, oxygen evolution, and oxygen reduction reactions in metal–air batteries, fuel cells, and water electrolysis. To facilitate further research and development, several important aspects related to CDs and their composite materials are summarized with analysis of the technical challenges in practical applications and discussion of the possible development perspectives.

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High volumetric supercapacitor with a long life span based on polymer dots and graphene sheets

Cited by 26 publications

References 26 publications

Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High‐Performance Hybrid Supercapacitors

Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High‐Performance Hybrid Supercapacitors

Integrated Carbon Dots-Matrix Structures: An Efficient Strategy for High-Performance Electric Double Layer Capacitors

A review of carbon dots and their composite materials for electrochemical energy technologies

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