Graphene For High-performance Supercapacitors Research Articles

Metal-incorporated laser-induced graphene for high performance supercapacitors

High performance supercapacitors are promising to address the rising energy conversion and storage challenges. Revealing the role of heteroatom incorporation and nanoparticle anchoring in modifying the capacitive properties of graphene-based electrodes is scientifically important to boost the supercapacitor performance, but technically challenging. We demonstrate a simple, but efficient route to fabricate porous graphene with effective heteroatom incorporation and metal nanoparticles anchoring by laser direct writing metal-coated polyimide films. Silver (Ag), copper (Cu), titanium (Ti), and tellurium (Te) are introduced into the porous laser-induced graphene (LIG) as dopants and nanoparticles. Compared to Ti and Te, Ag and Cu exhibit high incorporation efficiency. Incorporation of Ag and Cu into the LIG sheets results in high level disorder and structure expansion, which contributes to the enhanced capacitive performance. All-solid-state micro-supercapacitors (MSCs) made from the metal-incorporated LIGs (M-LIGs) were assembled. The capacity performance of M-LIG-based MSCs exhibits a similar variation trend with respect to the metal type. Besides, the M-LIG-based MSCs exhibit excellent capacitance stability at a bending angle beyond 150°. The results suggest that the effective metal doping and the metal nanoparticle modification could elevate the structural defect density in graphene, therefore contributing to high carrier density and enhanced capacitive performance.

Solvothermal synthesis of CoCeSx quantum dots based on Bi-pyrene-terminated molecular wires modified porous graphene for high performance supercapacitors

Transition metal quantum dots (QDs) have attracted enormous attention in the field of energy storage in recent years due to their unique nano-size effect and flexible surface functionalities. It is worth noting that the aggregation of QDs will lead to the decline of electrochemical performance, so it is necessary to maintain its good dispersion stability. Bi-pyrene-terminated molecular wires (BPMW) can reduce the stacking of graphene, which is considered to be a good material for modifying graphene with desired porous structure, higher specific surface area, and more attachment sites for the loading of QDs. Here, rGO@BPMW@CoCeSx-QDs were successfully designed and constructed. In detail, CoCe bimetallic organic framework (CoCe-MOF) was grown in situ on BPMW modified graphene by two-step solvothermal method to afford porous composites of rGO@BPMW@CoCeSx-QDs (pore size range is 40–230 nm). The fabricated electrode based on rGO@BPMW@CoCeSx-QDs shows an excellent electrochemical capacitance of 1047 F g−1 at the current density of 1 A g−1 in a three-electrode system. Moreover, a solid-state asymmetric supercapacitor (ASC) device can be fabricated based on the synthesized rGO@BPMW@CoCeSx-QDs, and exhibits a high energy density of 32.3 Wh kg−1 at a power density of 750 W kg−1.

In Situ Synthesis of Cocesx Quantum Dots Based on Bifunctional Conducting Molecules Modified Porous Graphene for High Performance Supercapacitors

In Situ Synthesis of Cocesx Quantum Dots Based on Bifunctional Conducting Molecules Modified Porous Graphene for High Performance Supercapacitors

Hydrophilic carbon fiber paper based electrode coated with graphene for high performance supercapacitors

In this paper, we report a facile and cost-effective approach to synthesis carbon fiber paper (CFP) based electrode coated with reduced graphene oxide (RGO) by vacuum filtration and carbonization. The SEM image showed that graphene was deposited on each individual carbon fiber and the hybrid electrode paper retained its three dimensional structure which provided efficient percolation path ways for electrons. The specific capacitance of the hybrid paper reached 1076 mF cm−2 at 5 mV s−1 according to cyclic voltammetry measurement. Further, the assembled symmetric supercapacitor delivered a high capacitance of 344 mF cm−2 at 0.5 mA cm−2. In a word, this feasible method should be appropriate for the fabrication of carbon fiber paper based electrodes.

Hierarchical construction of polyaniline nanorods on sulfonated graphene for high-performance supercapacitors

Herein, polyaniline (PANI)/sulfonated graphene (SG) hierarchical composites was prepared through the growth of polyaniline nanorods on the surface of SG. The morphology and structure of the composites were analyzed by scanning electron microscopy, fourier transform infrared spectroscopy, raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that SG was beneficial to the form of uniform PANI nanorods, and strong interactions could be formed between them. Due to the synergistic effect between PANI and SG, The SG/PANI composite electrode exhibited excellent electrochemical performances, especially extraordinarily high-rate capability. When the current density increased to 50 A g−1, SG/PANI with 81.5% PANI presented a high specific capacitance of 477.5 F g−1, which remained 86.3% of its initial value at 0.5 A g−1. The cycle life test show the composites have excellent stability (still remain 96.7%) after 2000 cycles. Moreover, an asymmetric supercapacitor was assembled coupling with graphene, which demonstrated remarkable specific energy density and power density simultaneously. The highest values could achieve 56.34 Wh kg−1 and 1200 W kg−1.

Electrophoretic Deposition of Nitrogen-Boron Co-Doped Graphene for High Performance Supercapacitors

In present condition, the ever-growing demand for sustainable and renewable energy resources, limited fossil fuels and environment issues like solar, wind, global warming and hydro energy have become a focal point of the leading world power and research [1-2]. Recently, supercapacitors due to their high power density (>10 kWkg-1), long cycle life (>105 cycles) and fast charge discharge response have captivated much interest. However, the poor energy density of supercapacitors (SCs) is the main issue, which hinders their potential industrial utilization [3-4]. However poor energy density of supercapacitor (SCs) is the main issue, which hinders their high potential industrial utilization. Basically, carbon based materials (CNT, graphene, activated carbon and mesoporous carbon) are used as the active electrode materials for the development of practical electric double layer supercapacitors (EDLCs). Besides this, the chemical doping of foreign atoms (such as N, B, P, I and S) in the carbon based materials is an effective tool to achieve the electron-donor characteristics, which effectively enhance the electrochemical performance of the material [5]. Such doping of heteroatoms in graphene would provide acid/base characteristics for upgraded electrochemical properties. Among the pure graphene, N and B co-doped graphene has attracted a lot of interest because of its superior electrochemical properties, cost-effective and eco-friendly behavior. In this work we developed a simple one step hydrothermal method to prepare N, B co-doped graphene at low temperature 180°C. Melamine diborate precursor has been utilized as source of N and B. Electrodes fabrication process done by the electrophoretic deposition (EPD) technique at 50 V. Best fabricated sample, labeled as NBG-0.7, exhibits highest specific capacitance of 217 Fg-1 at the scan rate of 5 mVs-1 which is about 1.2 times higher than the specific capacitance (180 Fg-1 at 5 mVs-1) of pristine reduced graphene oxide. The structural analysis, morphological studies, thermal stability and specific surface area of pure rGO and N, B co-doped graphene have been investigated via XRD, FE-SEM, TGA, TEM and BET surface area analyzer. The electrochemical measurements have been carried out using three electrodes measurement system in 6M KOH electrolyte using cyclic voltammetry (CV), galvanostatic charge-discharge cycling (GCD) and electrochemical impedance spectroscopy (EIS). Keywords: N, B co-doping; reduced graphene oxide; energy storage; supercapacitors References： [1] T. R. Cook, D. K. Dogutan, S. Y. Reece, Y. Surendranath, T. S. Teeth and D. G. Nocera, Chem. Rev., 2010, 110, 6474. [2] Renewable Energy Policy Network for the 21 st Century (REN21), Renewables Global Status Report, 2016, ISBN 978–3-9818107–0-7. [3] H. Jiang, P. S. Lee and C. Li, Energy Environ. Sci., 2013, 6, 41. [4] X. Lang, A. Hirata, T. Fujita and M. Chen, Nat. Nanotechnol., 2011, 6, 232. [5] Yong Qin, Jie Yuan , Juan Li, Dongchang Chen, Yong Kong, Fuqiang Chu ,Yongxin Tao, and Meilin Liu Adv. Mater. 2015, 27, 5171–5175. Figure 1

In situ growth of single-stranded like poly (o-phenylenediamine) onto graphene for high performance supercapacitors

Herein, we present the first report on a new strategy to synthesize a kind of stereoregular poly (o-phenylenediamine) (PoPD)-graphene nanocomposite bound only by chemical bond via in situ growth of single-stranded like PoPD onto graphene for high performance supercapacitor. Firstly, aniline groups are grafted onto graphene oxide (GO) surface by diazotization reaction to prepare aniline functionalized graphene oxide (a-GO), and then o-phenylenediamine (oPD) monomers are polymerized on a-GO surface to form PoPD wrapped graphene oxide (a-GO/PoPD). Subsequently, the a-GO/PoPD are washed repeatedly to make the PoPD to anchor with aniline groups (GO-a-PoPD) to stay (due to the solubility of PoPD in aqueous solution), followed by reduction to obtain single-stranded like PoPD anchored graphene (r-GO-a-PoPD). Consequently, the r-GO-a-PoPD nanocomposite with special combining form and structure exhibits a high specific capacitance of 381Fg−1 in 1M H2SO4 at 1Ag−1, and 230Fg−1 in 6M KOH at 1Ag−1. Furthermore, the symmetric supercapacitor exhibits excellent stability, high energy density and power density. The achieved high electrochemical performance is ascribed to the stable connection of PoPD with graphene and the sufficient use of them, which provide high capacitance and stability.

In Situ Synthesis of Mesoporous NiMoO4 on Ball Milled Graphene for High Performance Supercapacitors

Hydrothermal method is used to in situ synthesize mesoporous graphene@NiMoO4 nanocomposites as supercapacitor electrodes. NiMoO4 nanorods are formed on fresh graphene surface, while scattered NiMoO4 nanoparticles are obtained on the surface of ball milled graphene. graphene@NiMoO4 nanocomposites electrodes exhibit a higher electrochemical performance compared with a pure NiMoO4 electrode, and the ball milled graphene@NiMoO4 electrodes have the maximum specific capacitance of 2100 F g−1 at 1 A g−1 discharge current and maintains at least 92% of its initial capacitance after 5000 operational cycles. Such an enhanced supercapacitive performance originates from the mesoporous structure, more electroactive sites, large specific surface area, high electrical conductivity and synergistic effect between NiMoO4 and the graphene.

Layer-dependent growth of two-dimensional Co3O4 nanostructure arrays on graphene for high performance supercapacitors

Two-dimensional (2D) metal oxide nanostructure arrays have demonstrated great potential in high performance supercapacitors. The thickness of the 2D nanostructure, the building block of the arrays, has significant influence on pseudocapacitive properties of the arrays, thus their thickness optimization strategy is of great importance to the development of these 2D metal oxide nanostructure arrays, which is eagerly expected but rarely reported. Herein, an integrate hybrid electrode is designed and fabricated via the in-situ synthesis of Co3O4 nanoflake arrays on the nickel@graphene foam via a facile hydrothermal method. Furthermore, the layer number of graphene is adjusted from bilayer to multilayer to investigate the effects of graphene layers on the growth of Co3O4 nanoflake arrays. It is found that the thickness of Co3O4 nanoflakes can be tuned from 70 nm to 13 nm with the increase of the layer number of the graphene sheets due to the different surface diffusion coefficient of Co3O4 nanoparticles. The results of electrochemical measurements demonstrate that the hybrid electrode with the thinner nanoflakes presents higher specific capacitance because of the full utilization of the electroactive Co3O4. Particularly, the Co3O4/graphene/Ni hybrid electrode with 13 nm-thick nanoflake delivers a high specific capacitance of 1.75 F cm−2 at 1 mA cm−2 Additionally, a capacitance increase of 12.2% of the initial capacitance is observed after 5000 cycles at a current density of 10 mA cm−2. Our strategy brings new perspectives on optimizing 2D nanostructure arrays for various structure-sensitive applications.

One-step synthesis of surface-enriched nickel cobalt sulfide nanoparticles on graphene for high-performance supercapacitors

Binary metal sulfide@graphene composites have held great promising as electrode materials for supercapacitors (SCs). However, synthesis of nanosized binary metal sulfides that uniformly distribute on graphene in a simple way is still an enormous challenge. Herein we report a one-step solvothermal method employing poly (acrylic acid) (PAA) additive to fabricate well-dispersed nickel-cobalt sulfide nanoparticles on graphene (marked as Ni-Co-S@G) used in both traditional and flexible supercapacitors. The Ni-Co-S@G traditional electrode exhibits high specific capacitance at high rate (1021Fg−1 at 20Ag−1) and high capacitance retention (92.1% after 5000 cycles at 10Ag−1). Such outstanding performances are benefited from its unique integrated nanostructure which offers rich electroactive surface sites as well as favourable conductivity. Furthermore, asymmetric supercapacitor (ASC) of Ni-Co-S@G//reduced graphene hydrogels (RGH) delivers high energy density (39.5Whkg−1 at power density of 1778Wkg−1) as well as excellent cycle stability (84.4% capacitance retention after 15,000 cycles). Besides, binder-free flexible electrode with satisfied electrochemical properties was successfully fabricated by directly growing Ni-Co-S@G on active carbon fibre cloth (ACC). This work provides a facile and effective way to optimize the capacitive performances of binary metal sulfide@graphene composites, and also promotes the progress of the supercapacitor technology.

Fabrication of carbon-coated NiO supported on graphene for high performance supercapacitors

We report a feasible strategy for the synthesis of the carbon-coated NiO nanoparticles supported on graphenes and investigate their application as supercapacitor electrodes.

Dimensional tailoring of nitrogen-doped graphene for high performance supercapacitors

In supercapacitors, one dimensional graphene ribbons which form net-like porous structure demonstrate low mass transfer resistance at low frequency region and a consequent efficient charge transferability.

Porous nitrogen-rich carbon materials from carbon self-repairing g-C3N4 assembled with graphene for high-performance supercapacitor

Porous nitrogen-rich carbon derived from carbon self-repairing g-C3N4 with improved conductivity and more active sites exhibited high capacitance and good cycling performance due to the oxygen-containing groups and the carbon atoms close to the nitrogen as confirmed by XPS.

Spine-like nanostructured carbon interconnected by graphene for high-performance supercapacitors.

Recent studies on supercapacitors have focused on the development of hierarchical nanostructured carbons by combining two-dimensional graphene and other conductive sp2 carbons, which differ in dimensionality, to improve their electrochemical performance. Herein, we report a strategy for synthesizing a hierarchical graphene-based carbon material, which we shall refer to as spine-like nanostructured carbon, from a one-dimensional graphitic carbon nanofiber by controlling the local graphene/graphitic structure via an expanding process and a co-solvent exfoliation method. Spine-like nanostructured carbon has a unique hierarchical structure of partially exfoliated graphitic blocks interconnected by thin graphene sheets in the same manner as in the case of ligaments. Owing to the exposed graphene layers and interconnected sp2 carbon structure, this hierarchical nanostructured carbon possesses a large, electrochemically accessible surface area with high electrical conductivity and exhibits high electrochemical performance.

Hydrothermal synthesis of NiCo 2 O 4 nanowires/nitrogen-doped graphene for high-performance supercapacitor

Abstract NiCo 2 O 4 nanowires/nitrogen-doped graphene (NCO/NG) composite materials were synthesized by hydrothermal treatment in a water–glycerol mixed solvent and subsequent thermal transformation. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electrochemical performance of the composites was evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum techniques. NiCo 2 O 4 nanowires are densely coated by nitrogen-doped graphene and the composite displays good electrochemical performance. The maximum specific capacitance of NCO/NG is 1273.13 F g −1 at 0.5 A g −1 in 6 M KOH aqueous solution, and it exhibits good capacity retention without noticeable degradation after 3000 cycles at 4 A g −1 .

In situ growth of NiCo2S4 nanosheets on graphene for high-performance supercapacitors

We demonstrate a facile hydrothermal method for growth of ultrathin NiCo2S4 nanosheets on reduced graphene oxide (RGO), which exhibit remarkable electrochemical performance with higher capacitance and longer cycle life than the bare NiCo2S4 hollow spheres (HSs).