scholarly journals Crosslinked Polyethyleneimine Gel Polymer Interface to Improve Cycling Stability of RFBs

2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
Hyung-Seok Lim ◽  
Sujong Chae ◽  
Litao Yan ◽  
Guosheng Li ◽  
Ruozhu Feng ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Electrochemical Impedance ◽  
Active Species ◽  
Cycling Stability ◽  
Vanadium Redox Flow Battery ◽  
Flow Battery ◽  
X Ray ◽  
Polymer Interface ◽  
Eis Measurements

Redox flow batteries are considered a promising technology for grid energy storage. However, capacity decay caused by crossover of active materials is a universal challenge for many flow battery systems, which are based on various chemistries. In this paper, using the vanadium redox flow battery as an example, we demonstrate a new gel polymer interface (GPI) consisting of crosslinked polyethyleneimine with a large amount of amino and carboxylic acid groups introduced between the positive electrode and the membrane. The GPI functions as a key component to prevent vanadium ions from crossing the membrane, thus supporting stable long-term cycling. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to investigate the effect of GPI on the electrochemical properties of graphitic carbon electrodes (GCFs) and redox reaction of catholyte. X-ray photoelectron spectroscopy (XPS) and 1H nuclear magnetic resonance (NMR) spectra demonstrated that the crosslinked GPI is chemically stable for 100 cycles without dissolution of polymers and swelling in the strong acidic electrolytes. Results from inductively coupled plasma mass spectrometry (ICP-MS), Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy proved that the GPI is effective in maintaining the concentration of vanadium species in their respective half-cells, resulting in improved cycling stability because of it prevents active species from crossing the membrane and stabilizes the oxidation states of active species.

scholarly journals Thiourea-Grafted Graphite Felts as Positive Electrode for Vanadium Redox Flow Battery

2021 ◽  
Vol 8 ◽  
Author(s):  
Shangzhuo Wu ◽  
Xin Lv ◽  
Zhijun Ge ◽  
Ling Wang ◽  
Lei Dai ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Positive Electrode ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Peak Potential ◽  
Flow Battery ◽  
X Ray ◽  
Vanadium Redox ◽  
Acid Esterification ◽  
Electro Catalytic Activity

In this paper, thiourea was successfully grafted onto the surface of acid preprocessed graphite felts [sulfuric acid-treated graphite felt (SA-GFs)] by thiol-carboxylic acid esterification. The thiourea-grafted graphite felts (TG-GFs) were investigated as the positive electrode for vanadium redox flow battery (VRFB). X-ray photoelectron spectroscopy results suggested that thiourea was grafted into the surface of graphite felts. The cyclic voltammetry showed that the peak potential separation decreased by 0.2 V, and peak currents were greatly enhanced on TG-GF electrode compared with SA-GF electrode, implying improved electro-catalytic activity and reversibility of TG-GF electrode toward VO2+/VO2+ redox reaction. The initial capacity of TG-GF-based cell reached 55.6 mA h at 100 mA cm−2, 22.6 mA h larger than that of SA-GF-based cell. The voltage and energy efficiency for TG-GF-based cell increased by 4.9% and 4.4% compared with those of SA-GF-based cell at 100 mA cm−2, respectively.

scholarly journals Mechanism of Depression by Fe3+ During Hemimorphite Flotation

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 790
Author(s):  
Junbo Liu ◽  
Shuming Wen ◽  
Qicheng Feng ◽  
Qian Zhang ◽  
Yijie Wang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Electrochemical Impedance ◽  
Test Results ◽  
X Ray ◽  
Inductively Coupled ◽  
Adsorption Analysis ◽  
Plasma Mass Spectrometry ◽  
Local Electrochemical Impedance Spectroscopy ◽  
Ph Range

Sulfide hemimorphite can be depressed by Fe3+ during flotation. In this study, the depression mechanism was studied by microflotation, inductively-coupled plasma mass spectrometry, local electrochemical impedance spectroscopy (LEIS), and X-ray photoelectron spectroscopy (XPS). Flotation test results suggested that sulfated hemimorphite can be depressed by Fe3+ across the entire pH range. LEIS, adsorption analysis, and XPS indicated that S species were adsorbed on hemimorphite as ZnS. The sulfide film was attenuated and no adsorbed Fe species were found after treatment with Fe3+. The results indicate that Fe3+ reacts with the ZnS film, which decreases the number S species, and this leads to hemimorphite depression.

scholarly journals Pentavalent Vanadium Species as Potential Corrosion Inhibitors of Al2Cu Intermetallic Phase in the Sulfuric(VI) Acid Solutions

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1946 ◽  
Author(s):  
Przemysław Kwolek ◽  
Barbara Kościelniak ◽  
Magdalena Wytrwal-Sarna
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Corrosion Inhibitors ◽  
Electrochemical Impedance ◽  
Intermetallic Phase ◽  
Open Circuit ◽  
Acid Solutions ◽  
Scanning Calorimetry ◽  
Electrochemical Impedance Spectra ◽  
X Ray

The objective of this work was to test vanadium isopolyoxoanions as potential corrosion inhibitors of the intermetallic phase Al2Cu in sulfuric acid solutions at pH = 1.3 and 2.5. The intermetallic was melted in an electric arc furnace. Its phase composition was confirmed using X-ray diffraction, light microscopy, and differential scanning calorimetry. Then Al2Cu corrosion kinetics was studied. Chemical composition of the solution after corrosion was determined using inductively coupled plasma-optical emission spectroscopy. The surface of corroded specimens was analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy. Subsequent electrochemical studies involved determination of open-circuit potential, electrochemical impedance spectra, and polarization curves. It was found that the Al2Cu phase corrodes selectively and vanadium isopolyoxoanions increase this process both at pH = 1.3 and 2.5 with two exceptions. Corrosion inhibition was observed for 100 and 200 mM of Na3VO4 at pH 1.3, with inhibition efficiency 78% and 62% respectively, due to precipitation of V2O5.

Highly Hydroxylated Graphite Felts Used as Electrodes for a Vanadium Redox Flow Battery

2014 ◽  
Vol 936 ◽  
pp. 471-475 ◽  
Author(s):  
Wen Wen Li ◽  
You Qun Chu ◽  
Chun An Ma
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Vanadium Redox Flow Battery ◽  
Electrochemical Characteristics ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Oh Groups ◽  
Average Current ◽  
Vanadium Redox ◽  
Mixed Acids

The highly hydroxylated graphite felts (GFs) were obtained by treating in mixed acids (V(HNO3)/V(H3PO4)=3:1) for different time at 80°C, and used as the electrodes for all vanadium redox flow battery (VRB). The physical, chemical and electrochemical characteristics of these GFs are characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, cyclic voltametry, electrochemical impedance spectroscopy and charge/discharge test. The excellent electrochemical properties of the treated GFs to VRB electrode reactions can be ascribed to the enhancement of the interaction between vanadium ions with –OH groups introduced by acid treatment. Using GFs treated in the mixed acids for 8 h as electrodes, the VRB exhibits excellent performance under a current density of 20 mA/cm2. The average current efficiency, voltage efficiency and energy efficiency are about 97%, 83.3% and 78%, respectively.

scholarly journals High Electrochemical Performance of Nanotube Structured ZnS as Anode Material for Lithium–Ion Batteries

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1537 ◽  
Author(s):  
Wen Zhang ◽  
Junfan Zhang ◽  
Yan Zhao ◽  
Taizhe Tan ◽  
Tai Yang
Keyword(s):  
Lithium Ion Batteries ◽  
Discharge Capacity ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Zno Nanorods ◽  
Sorption Isotherms ◽  
Lithium Ion ◽  
Chemical Compositions ◽  
X Ray ◽  
Eis Measurements

By using ZnO nanorods as an ideal sacrificial template, one-dimensional (1-D) ZnS nanotubes with a mean diameter of 10 nm were successfully synthesized by hydrothermal method. The phase composition and microstructure of the ZnS nanotubes were characterized by using XRD (X-ray diffraction), SEM (scanning electron micrograph), and TEM (transmission electronic microscopy) analysis. X-ray photoelectron spectroscopy (XPS) and nitrogen sorption isotherms measurements were also used to study the information on the surface chemical compositions and specific surface area of the sample. The prepared ZnS nanotubes were used as anode materials in lithium-ion batteries. Results show that the ZnS nanotubes deliver an impressive prime discharge capacity as high as 950 mAh/g. The ZnS nanotubes also exhibit an enhanced cyclic performance. Even after 100 charge/discharge cycles, the discharge capacity could still remain at 450 mAh/g. Moreover, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were also carried out to evaluate the ZnS electrodes.

MICROSTRUCTURE AND PROPERTIES OF THE Ni–B AND Ni–B–Ce ULTRASONIC-ASSISTED ELECTROLESS COATINGS

2018 ◽  
Vol 25 (06) ◽  
pp. 1950006 ◽  
Author(s):  
WEI QIAN ◽  
HAOTIAN CHEN ◽  
CHENQI FENG ◽  
LIYING ZHU ◽  
HUANMING WEI ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Electrochemical Impedance ◽  
Low Carbon Steel ◽  
Amorphous Structure ◽  
Low Carbon ◽  
X Ray ◽  
Inductively Coupled ◽  
Hardness Tester

We successfully obtained Ni–B and Ni–B–Ce coatings with and without sonication on low-carbon steel (Q235) through electroless plating with the deposition time of 60[Formula: see text]min. The surface morphology and elemental composition of the coatings were evaluated by scanning electron microscopy (SEM) and inductively coupled plasma (ICP). The 11[Formula: see text][Formula: see text]m thick sonicated Ni–B–Ce (Son-Ni–B–Ce) coating is uniform with the composition of Ni 87.1%, B 6.2% and Ce 6.6%. X-ray diffraction (XRD) measurements implied a typical broaden peak around 44∘, considered as amorphous structure which was confirmed by selected area electron diffraction pattern (SAED). Atomic force microscopy (AFM) showed a typical circular pit of Ni–B–Ce coating and Son-Ni–B–Ce coating. X-ray photoelectron spectroscopy (XPS) revealed the chemical status of coating components. The mechanical and corrosion resistance properties were determined by Vickers hardness tester, potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy (EIS) in 3.5[Formula: see text]wt. % NaCl solution. As a result, the Son-Ni–B–Ce coating revealed the optimum hardness (956[Formula: see text]HV), minimum roughness [Formula: see text] (92.38[Formula: see text]nm) and excellent corrosion resistance (3.65[Formula: see text][Formula: see text]Acm[Formula: see text] among all coatings.

A new core–shell Z-scheme heterojunction structured La(OH)3@In2S3 composite with superior photocatalytic performance

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
Shuting Hu ◽  
Junfeng He ◽  
Fuming Chen ◽  
Bin Liu ◽  
Wangjian zhai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Electrochemical Impedance ◽  
Cost Effective ◽  
Active Species ◽  
X Ray ◽  
Methylene Orange ◽  
Photodegradation Rate ◽  
Redox Ability

AbstractConstructing Z-scheme heterojunction photocatalyst with strong redox ability to make for enhanced photocatalytic performance and efficient charge separation is extremely attractive but still underdeveloped. Herein, a Z-scheme heterojunction structured La(OH)3@In2S3 composite (labeled by “LIS”) with photocatalytic for the methylene orange (MO) degradation under simulated light irradiation has been developed. The as-prepared LIS, together with commercial La(OH)3 and pure In2S3 fabricated with the identical processing method and starting materials as those of LIS, was characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra and electrochemical impedance spectroscopy. The results show the heterojunction of La(OH)3/In2S3 has prolonged the lifetime of the photo-generated carriers. The photocatalytic activity test shows that over only a small amount (0.02 g in 100 ml MO) of LIS, the photodegradation rate of 95% toward MO can be obtained in 90 min, which is about 3.4 times higher than that over pure In2S3. The active species trapping experiments indicate that there were four active species playing roles in photodegradation as the following order: e– = ∙OH < h+ < ∙O2–. A mechanism of Z-scheme heterojunction was proposed and well explained the enhanced photocatalytic performance. This work provides a new cost-effective photocatalyst with high photocatalytic properties.

scholarly journals Carbon-Coated SiO2 Composites as Promising Anode Material for Li-Ion Batteries

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4531
Author(s):  
Mihaela-Ramona Buga ◽  
Adnana Alina Spinu-Zaulet ◽  
Cosmin Giorgian Ungureanu ◽  
Raul-Augustin Mitran ◽  
Eugeniu Vasile ◽  
...  
Keyword(s):  
Anode Material ◽  
Photoelectron Spectroscopy ◽  
Coulombic Efficiency ◽  
Cycling Stability ◽  
Li Ion Batteries ◽  
Transfer Resistance ◽  
Promising Alternative ◽  
X Ray ◽  
Carbon Coated ◽  
Li Ion

Porous silica-based materials are a promising alternative to graphite anodes for Li-ion batteries due to their high theoretical capacity, low discharge potential similar to pure silicon, superior cycling stability compared to silicon, abundance, and environmental friendliness. However, several challenges prevent the practical application of silica anodes, such as low coulombic efficiency and irreversible capacity losses during cycling. The main strategy to tackle the challenges of silica as an anode material has been developed to prepare carbon-coated SiO2 composites by carbonization in argon atmosphere. A facile and eco-friendly method of preparing carbon-coated SiO2 composites using sucrose is reported herein. The carbon-coated SiO2 composites were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetry, transmission and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, cyclic voltammetry, and charge–discharge cycling. A C/SiO2-0.085 M calendered electrode displays the best cycling stability, capacity of 714.3 mAh·g−1, and coulombic efficiency as well as the lowest charge transfer resistance over 200 cycles without electrode degradation. The electrochemical performance improvement could be attributed to the positive effect of the carbon thin layer that can effectively diminish interfacial impedance.

Ternary Composite of Molybdenum Disulfide-Graphene Oxide-Polyaniline for Supercapacitor

2021 ◽  
Author(s):  
Ke Qu ◽  
Yuqi Bai ◽  
Miao Deng
Keyword(s):  
Graphene Oxide ◽  
Molybdenum Disulfide ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Light Emitting Diode ◽  
Rate Capability ◽  
Energy Storage And Conversion ◽  
Carbon Paper ◽  
Power Sources ◽  
X Ray

Abstract The ever-increasing need for small and lightweight power sources for use in portable or wearable electronic devices has spurred the development of supercapacitors as a promising energy storage and conversion system. In this work, a simple, facile and easy-to-practice method has been developed to employ carbon paper (CP) as the support to coat molybdenum disulfide (MoS2) and graphene oxide (GO), followed by electrodeposition of polyaniline (PANI) to render CP/MoS2-GO-PANI. The preparation parameters, such as amounts of MoS2, GO and number of aniline electropolymerization cycles, have been optimized to render CP/MoS2-GO-PANI the best capacitive performance. The as-prepared optimal CP/MoS2-GO-PANI is characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy. The supercapacitive properties of CP/MoS2-GO-PANI as an electrode have been evaluated electrochemically via cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy testing. CP/MoS2-GO-PANI delivers a specific capacitance of 255.1 F/g at 1.0 A/g and exhibits excellent rate capability under larger current densities. Moreover, a symmetrical supercapacitor is assembled and three are connected in series to power a light-emitting diode for ~15 minutes, demonstrating the promising application potential of CP/MoS2-GO-PANI-based supercapacitor.

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