Untreated Natural Graphite as a Graphene Source for High-Performance Li-Ion Batteries

Simón, María; Benítez, Almudena; Caballero, Álvaro; Morales, J.; Vargas, Óscar

doi:10.3390/batteries4010013

Cited by 32 publications

(19 citation statements)

References 33 publications

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“…Raman spectroscopy is an effective technique for the observation of carbonaceous materials include graphene and GO. It can also be applied to detect organized and disorganized crystalline structures and to identify the single or multilayer properties of the GO sample [ 27 , 51 ]. Structural changes that occur during the chemical conversion from graphite to GO were also represented in their respective Raman spectra in Figure 7 [ 52 ].…”

Section: Resultsmentioning

confidence: 99%

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Graphene oxide based coconut shell waste: synthesis by modified Hummers method and characterization

Sujiono

Zurnansyah

Zabrian

et al. 2020

Heliyon

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Graphene oxide (GO) based on coconut shell waste was successfully synthesized using a modified Hummers method, and the obtained GO was confirmed using XRD, FTIR, Raman spectroscopy, UV-Vis spectroscopy, and SEM-EDX. The XRD spectroscopy obtained the fractional content of the 2H graphite phase of 71.53%, 14.47% phosphorus, 10.02% calcium, and 3.97% potassium in coconut shell charcoal, where the GO sample tend to forms a phase of reduced graphene oxide (rGO). FTIR spectra shows compound functional groups of hydroxyl (- OH) at peak 1 (3449.92 cm −1 ), carboxyl (-COOH) at peak 2 (1719.42 cm −1 ) and peak 3 (1702.62 cm −1 ), and alcohol (C–OH) at peak 4 (1628.12 cm −1 ) and epoxy (CO) at peak 5 (1158.51 cm −1 ), which is similar to the GO synthesis from pure graphite. Raman spectroscopy analysis shows that the value of the I D /I G intensity ratio of the GO sample was 0.89 with a 2D single layer, and SEM results showed that surface morphology with an abundance of granular particles were found with different size distribution. The UV-visible results showed sufficient optical properties characterized by the spectrum, which formed because of the light absorption of the energy passed on the sample. The bandgap energy value of the sample obtained by the Tauc plot method was 4.38 eV, which indicates semiconductor properties.

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Section: Resultsmentioning

confidence: 99%

“…The observed results strongly indicate the similarities I D /I G intensity ratio with that reported by Simon et al . [ 27 ], and Kim et al ., [ 54 ]. The 2D band is a crucial parameter for determining the formation or layer totals of the GO sample [ 9 ].…”

Section: Resultsmentioning

confidence: 99%

Graphene oxide based coconut shell waste: synthesis by modified Hummers method and characterization

Sujiono

Zurnansyah

Zabrian

et al. 2020

Heliyon

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“…According to the XRD spectra, decline in the intensity of this peak demonstrated the transformation of graphite to graphene [34]. The thickness of graphene products was estimated by applying Scherrer's equation which is stated as D002 = Kλ/Bcos θ. D002, K, λ, B, and θ are the thickness of the graphene, a constant based on the crystal shape (0.89), the wavelength of the X-ray (0.15406 nm), the full width half maximum (FWHM) of the characteristic peak of graphene, and the scattering angle, respectively [35,36].…”

Section: Resultsmentioning

confidence: 99%

Graphene Synthesis by Ultrasound Energy Assisted Exfoliation of Graphite in Various Solvents

Gürünlü¹,

Taşdelen-Yücedağ²

2020

Preprint

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Liquid Phase Exfoliation (LPE) method has been gaining increasing interest by academic and industrial researchers due to its simplicity, low-cost, and scalability. High intensity ultrasound energy was exploited to transform graphite to graphene in the solvents of dimethyl sulfoxide (DMSO), N,N-dimethyl formamide (DMF), and perchloric acid (PA) without any surfactants or ionic liquids. The crystal structure, number of layers, particle size, and morphology of the synthesized graphene samples were characterized by X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Ultraviolet visible (UV–vis) spectroscopy, Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM). XRD and AFM analyses indicated that G-DMSO and G-DMF have few layers and G-PA has multilayers. The layer numbers of G-DMSO, G-DMF, and G-PA were determined as 9, 10, and 21, respectively. By DLS analysis, the particle sizes of graphene samples were estimated in a few micrometers. TEM analyses showed that G-DMSO and G-DMF possess sheet-like fewer layers and also, G-PA has wrinkled and unordered multilayers.

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“…One way towards porous graphene electrodes is the employment of graphene nanosheets [21][22][23]. Still, graphite is an appealing Li-O 2 cathode material from a technological perspective, because it is fairly abundant, low-cost and well-researched [24][25][26][27]. Compared to graphene, graphite electrodes are rarely reported, because the formation of discharge products takes place on the cathode surface and graphene-like materials mainly offer more specific surface area than milled graphite.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Discharge Behavior of Graphite Nanosheet Electrodes in Lithium-Oxygen Batteries

2019

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Lithium-oxygen (Li-O2) batteries require rational air electrode concepts to achieve high energy densities. We report a simple but effective electrode design based on graphite nanosheets (GNS) as active material to facilitate the discharge reaction. In contrast to other carbon forms we tested, GNS show a distinctive two-step discharge behavior. Fundamental aspects of the battery’s discharge profile were examined in different depths of discharge using scanning electron microscopy and electrochemical impedance spectroscopy. We attribute the second stage of discharge to the electrochemically induced expansion of graphite, which allows an increase in the discharge product uptake. Raman spectroscopy and powder X-ray diffraction confirmed the main discharge product to be Li2O2, which was found as particulate coating on GNS at the electrode top, and in damaged areas at the bottom together with Li2CO3 and Li2O. Large discharge capacity comes at a price: the chemical and structural integrity of the cathode suffers from graphite expansion and unwanted byproducts. In addition to the known instability of the electrode–electrolyte interface, new challenges emerge from high depths of discharge. The mechanistic origin of the observed effects, as well as air electrode design strategies to deal with them, are discussed in this study.

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Untreated Natural Graphite as a Graphene Source for High-Performance Li-Ion Batteries

Cited by 32 publications

References 33 publications

Graphene oxide based coconut shell waste: synthesis by modified Hummers method and characterization

Graphene oxide based coconut shell waste: synthesis by modified Hummers method and characterization

Graphene Synthesis by Ultrasound Energy Assisted Exfoliation of Graphite in Various Solvents

Anomalous Discharge Behavior of Graphite Nanosheet Electrodes in Lithium-Oxygen Batteries

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