mehran javanbakht

The current study explores the film forming ability of a new additive Methyl p-toluene sulfonate (MPTS) on the LiMn2O4 (LMO) electrode and its effect on the electrochemical characteristics of lithium-ion battery. Based on the density functional theory analysis of the ionization energy (AIE) of MPTS and carbonate solvents, it was found that MPTS possesses the lowest AIE at 693.2 kJ/mol, suggesting a higher susceptibility to oxidation compared to the electrolyte solvents. Electrochemical and physicochemical analyses including linear sweep voltammetry, electrochemical impedance spectroscopy, field-emission scanning microscopy, indicated that the electrolyte with MPTS is prone to create a protective film with low impedance on the cathode electrode, which enhances the stability of the electrolyte and electrode upon battery cycling. The LMO/Li half-cell with 1.5% MPTS exhibits outstanding cyclic performance, retaining 90.53% of its capacity after 100 cycles, in comparison to 81.84% for the pristine electrolyte at high voltage. This improvement is because of the creation of a protective sulfur-containing layer on the cathode surface, which effectively prevents electrolyte degradation, reduces interfacial impedance, and enhances overall battery performance.

Atom Transfer Radical Polymerization (ATRP) is a beneficial technique for the preparation and design of multifunctional and nanostructured materials for a variety of applications. Macromolecular structure, order and functionality are of the most important factors and considerations in polymer science and ATRP enables precise control over these factors. This method aids synthesizing novel engineering polymeric materials which play an absolutely essential role in all aspects of our lives and there is a “must” to develop new and green methods to synthesize and produce novel materials as best as we can. In this research, we have synthesized novel graft copolymers of PVDF-g-PS and PVDF-g-PSSA via ATRP which have a variety of applications from membranes to Li-Ion batteries. These materials can be used to enhance the properties of Li-ion batteries’ separator operation. The characterization of the final copolymers was performed using Fourier transform infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance (1H-NMR) analyses. The grafting percentages obtained from 1H-NMR analyses are reported to be 2%, 13% and 44% for PVDF-g-PS (I), PVDF-g-PS (II) and PVDF-g-PSSA copolymer samples, respectively.

To develop proton exchange membrane blends based on polybenzimidazole (PBI), a novel polymer blend membrane consisting of PBI and sulfonated poly 1,4-phenylene ether ether sulphone (SPEES) was prepared by solution casting method. The goal of the work was to study the performance of the acid-base composition on its properties, such as mechanical stability, thermal stability, and proton conductivity of PBI-SPEES blend membranes. The N−H···O interactions between the PBI and SPEES in the blend membranes indicated that the two polymers form a miscible blend. The acid uptake (12 moles) and proton conductivity (101 mS/cm in 160 °C) of the blend membranes were significantly ameliorated as compared to pure phosphoric acid-doped PBI (APBI) membranes. A single glass transition value of PBI-SPEES blend membranes which were between the glass transition value of the PBI and SPEES membranes confirmed the miscible properties of PBI-SPEES blend membranes. The presence of SPEES in the blend membranes decreases the friability and hardness and increases the flexibility and proton conductivity of APBI membranes. According to the PEM fuel cell results, with a high-power density of 0.65 W/cm2 at 180 ºC, the PBI-SPEES blend membranes have a high potential for use as an appropriate membrane in the fuel cells.

In the current paper, a three-dimensional, steady-state model has been introduced for novel proton exchange membranes (PEM) containing dicationic ionic liquids appropriatefor elevated temperature fuel cells under an anhydrous environment. Development of such a model requires utilizing the 3D geometry and detailed mesh grid and discretization of momentum. Mass and electric charge balance equations were solved based on the information obtained from electrical and electrochemical models within various areas of the cell such as porous electrodes, gas channels, and the solid parts and current collector, especially. Additionally, a description of the electrochemical reactions on the active sites of the anode and cathode electrodes, and ions' movement through the electrolyte is considered. The equations were solved by applying a finite element method solver. Finally, the results of the model are compared with the experimental data (current density-voltage graph). This graph shows a good correlation between the model and experiments validating the present simulation. This model is also able to predict PEMFC behavior under different operational conditions

In the present work, BaCe0.85Yb0.15O3-δ mixed metal oxide nanoparticles supplying strong acid sites and good hydrophilic nature were used for the first time to build organic-inorganic proton exchange membranes. Poly(vinyl alcohol) - BaCe0.85Yb0.15O3-δ (PVAYb) nanocomposite membranes were fabricated. Different analyses such as Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) spectroscopy, Fourier Transform Infra-Red (FT-IR) spectroscopy, and ThermoGravimetry Analysis (TGA) were used to characterize and study the structural properties of the obtained membranes. SEM and EDX analyses exhibited a homogenous dispersion of the nanoparticles in the nanocomposite membrane.  It was found that PVAYb1.5 had a better elemental distribution compared to PVAYb2.5 composite membrane. PVAYb nanocomposite membrane containing 1.5 wt.% of BaCe0.85Yb0.15O3-δ nanoparticles displayed a high proton conductivity value (64 mS/cm) at 70 °C operation temperature. The peak power density of 29 mW/cm2 was obtained with a peak current density of 210 mA / cm2 for as-prepared Proton Exchange Membrane Fuel Cell (PEMFC) equipped with PPYb1.5 nanocomposite membrane at 70 °C.

Solid polymer electrolytes (SPEs) show good structural flexibility and safety to meet the requirements of lithium-ion battery applications. Poly(vinylidene fluoride) (PVDF) is a semi-crystalline polymer which due to its desirable has been considered as promising candidate for fabrication of polymer electrolytes in Li-ion batteries. PEs usually have a low ionic conductivity at room temperature. In this study, in order to eliminate this problem and improve the ionic conductivity improving additives of lithium-ion battery graphene oxide (GO) were investigated. Then, the additive amount was optimized using the Morphology, Tensile strength, ionic conductivity, Li+ ion transference number and electrochemical stability, which determined the optimal amount of (GO). SEM images were shown that SPEs containing GO have more porosity in comparison with GPE without GO. By adding 0.004 wt% GO, the ionic conductivity of the PVDF/GO polymer electrolyte was increased significantly to 3.60 mS cm-1 for the composite and the transference number of Li+ ion was also increased to 0.74. The electrochemical stability of 4.6 V was achieved. The results show that GO not only increased the ionic conductivity of composite membrane but also improved the physical properties of the polymer electrolyte. This study shows that the PVDF/GO polymer electrolyte can be considered as a promising SPE for lithium ion batteries.

In this research, inorganic material type and content influence on coating of commercially available polypropylene (PP) separator were studied for improving its performance and safety as lithium ion battery separator. Heat-resistant nanopowders of Al2O3, SiO2 and ZrO2 were coated using polyvinylidene fluoride (PVDF) binder. Coating effects on the separators morphology, wettability, high temperatures dimensional stability and electrochemical properties were investigated via their scanning electron microscopy images, electrolyte contact angles, electrolyte uptakes, thermal shrinkages analysis and ion conductivities. Furthermore, their performances were studied as the lithium ion batteries separator. All the coated separators have lower thermal shrinkages compared to the commercial neat PP separator. In addition, almost all of the coated separators have shown higher porosities and electrolyte uptakes than those of the commercial neat PP separators. The coated separator with Al2O3 / binder ratio of 8 (MOA8) revealed highest improvement in electrolyte contact angle of 0 °, electrolyte uptake of 218 % (2.04 times increment), ion conductivity of 1.685 mS/cm (1.89 times increment), 52 % porosity compared with the neat PP separator due to proper coating surface morphology, interstitial cavities and a higher Al2O3 dielectric constant than SiO2. In terms of assembled battery discharge capacity reduction after 100 cycles, MOA8 separator showed better cyclic performance as 8.89 % compared with that of the neat PP separator as 16.6 %.

Polyvinylidene fluoride (PVDF) is a semicrystalline polymer which has been extensivelyapplied in scientific research and industrial processes owing to its desirable featuressuch as excellent dielectric properties, suitable mechanical resistance, high thermal stability,good chemical resistance. PVDF membranes can be applied in a wide range of applicationsincluding waste water treatment, gas separation, and separator and polymer electrolyte inlithium ion batteries. PVDF-based polymer electrolytes in lithium ion batteries should havelow thickness as well as an appropriate porosity with good mechanical strength and highelectrochemical stability. Applying pristine PVDF based polymer electrolytes may causeinternal short circuit which will influence the performance of the Li-ion batteries. BlendingPVDF with other polymers and incorporation of inorganic fillers have been considered aseffective methods to improve the performance of PVDF-based electrolytes. In this paper,PVDF-based electrolytes and their performance requirements have been investigated. Thefabrication methods of PVDF membranes and the known strategies which are applied toimprove their mechanical and electrochemical characteristics have also been described.Furthermore, the ionic conductivity and electrochemical performance of PVDF-basedlithium-ion batteries are discussed.

In this work, we synthesized nano plate oxalate precursor via solvothermal method to obtain Nano Sponge Li1.2Mn0.54Ni0.13Co0.13O2 (NS-LMNCO) cathode material. During solvothemal process, ethanol and water solvents arrange oxalate nuclei to form plate-like shape. With increasing temperature at calcination step, the oxalate precursor is converted to NS-LMNCO by removing CO2. The structure, morphology and elemental composition of synthesized samples are investigated with X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron spectroscopy (XPS), respectively. The thickness and length of nano plate are 60 nm and 2 μm, respectively. However, the diameter of particles made NS-LMNCO is 40 nm. The NS-LMNCO delivers discharge capacities of 207.6 mAh g-1 at 0.1 C. Furthermore, electrochemical data show that NS-LMNCO sample retain discharge capacities of 147.5 mAh g-1 (71.1% of the first discharge capacity) after 50 cycles at 0.1 C-rate. The results obtained in this work clearly confirmed that electrochemical properties of lithium ion cell e.g. specific capacity, cycle life and rate performance can be significantly controlled by properties of active materials, especially cathode particles, e.g. porosity, surface area and density related to morphology of active particles.

A patent analysis method has been applied to study patenting activities on development of liquid electrolytes for lithium-ion batteries. The method is done via two steps:First, planning a searching strategy and second, an analysis of the information obtained from selected patents. The results showed that the patents on liquid electrolytes for Li-ion cells were published in a time interval of 1964 to 2017 with a significant growing publishing number between 2010 and 2013. The obtained patenting time trend illustrated that the technical knowledge of this technology has been became probably mature and it is predicted that patenting trend in this area will be continued with a slow rate in upcoming years. It was found that Japan, China, South Korea and USA are the most targeted countries for patent publication in this field which is an indicator of their potential market for this technology. Investigation of the competitors patent assignees showed that LG CHEM, Mitsubishi Chemicals, UBE Industries, Sony and Sanyo Electric are the pioneer players having more patented publications among others, respectively.

Platinum particles were grown directly by an electrodeposition process on electrochemically treated carbon paper (CP) for kinetic study of carbon monoxide (CO) desorption. The treatment on CP was performed by applying −2 V for cathodic oxidation over 5 min. Treated CP was characterized by FTIR to investigate the oxygen groups on its surface. CO surface coverage at each temperature was determined by monitoring changes in Had (adsorbed hydrogen) desorption charge during CO stripping at different desorption times (300 to 1800 s). CO coverage of the cathodic electrode is lower than non-treated one in all temperatures. Desorption rate constants were calculated for cathodic and non-treated electrodes. From 25 to 85 °C, rate constants for cathodic electrode are higher than the non-treated electrode at all temperatures. The activation energies for desorption, estimated from data obtained by the experiments, are 28480 and 18900 J.mol-1 for non-treated and cathodic electrode, respectively. This shows that CO desorption is easier on the surface of the cathodic electrode than non-treated electrode due to the presence of oxygen surface groups.

There is no other naturally occurring defense agent against cancer that has a stronger effect than paclitaxel, commonly known under the brand name of Taxol®. The major drawback for the more widespread use of paclitaxel and its precious precursor, 10-deacetylbaccatin III (10 DAB III), is that they require large-scale extraction from different parts of yew trees (Taxus species), cell cultures, taxane-producing endophytic fungi, and Corylus species. In our previous work, a novel online two-dimensional heart-cut liquid chromatography process using hydrophilic interaction/ reversed-phase chromatography was used to introduce a semi-preparative treatment for the separation of polar (10-deacetylbaccatin III) and non-polar (paclitaxel) taxanes from Taxus baccata L. In this work, a combination of the absorbent (Diaion® HP- 20) and a silica based solid phase extraction is utilized as a new, efficient, and cost effective method for large-scale production of taxanes. This process avoids the technical problem of two-dimensional preparative liquid chromatography. The first stage of the process involves discarding co-extractive polar compounds including chlorophylls and pigments using a nonpolar synthetic hydrophobic absorbent, Diaion® HP-20. Extract was then loaded on to a silica based hydrophilic interaction solid phase extraction (silica 40-60 micron). Taxanes was eluted using a mixture of water and methanol at the optimized ratio of 70:30. Finally, the fraction containing taxanes was applied to semi-preparative reversed phase HPLC. The results revealed that using this procedure, paclitaxel and 10-DAB III could be obtained at 8 and 3 times more, respectively than by the traditional method of extraction.

The active cauliflower-like LiFePO4 (LFP/Cin) material was synthesized with hydrothermal process in the presence of glucose and then calcined at 600 °C. The physical properties, particle size and morphology of obtained samples were investigated with the Xray diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The electrochemical performance of nano-composites was studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic cycling performance. The CV curves show that LFP/Cin has higher electrochemical reactivity for lithium insertion and extraction than the LFP conventional cathode material. EIS measurements demonstrated that Rct for LFP/Cin is 70 and 50 percent lower compared to LFP and LFP/Cex respectively. The initial discharge capacity of LiFePO4/Cin cathode material delivers about 133.92 mAh g−1 (82% of theoretical capacity) at 0.1 C and cycling stability with 96.3% of capacity retention after 40 cycles at 0.1 C. Electrochemical tests demonstrate that in-situ carbon coating play an important role in the improvement of battery performance with increasing the conductivity, reduce the particles size and unique structure.

Thiolfunctionalized silica nanoparticles (SiO2– SH) were prepared by sol-gel method through using 3mercaptopropyltrimethoxysilane and nanosized silica. The effect of the pH of the silane solution on grafting efficiency of silica nano-particles was scrutinized. It was found that the reaction between silane and silica nanoparticles was more effective at low pH. The FTIR spectroscopy and CHNS analyses were used to study the chemistry of the modified nanoparticles. It was found that the SiO2–SH groups could effectively remove the heavy metal ions (Pb2, Ni2, and Hg2) in the solution through electrostatic and chemical interactions. The adsorption isotherm and adsorption capacity of the functional nanoparticles for different metal ions, and its selectivity were investigated. Similarly, the effect of the pH values on the adsorption of metal ions was studied. The strong adsorption ability of SiO2–SH can be attributed to the functional nonoparticles with rich thiol groups facilitating the mass transport of metal ions to the active sites. These functional nanoparticles were blended in poly(ether sulfone) membranes as an adsorbent to improve the membranes separation and selectivity properties for removal of heavy metal ions.

In this study, the activity, stability and performance of carbon supported platinum (Pt/C) electrocatalyst in cathode and carbon supported Pt and ruthenium (PtRu/C) electrocatalyst in anode of direct methanol fuel cell (DMFC) were studied. The Pt/C and PtRu/C electrocatalysts were prepared by impregnation reduction method. The β-D-glucose was used as protection agent to reduce the particle size and improve performance of prepared electrocatalysts. The prepared electrocatalysts were characterized by using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The results of XRD and TEM showed that the average particle size of metals in prepared electrocatalysts is between 2-3 nm. The cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry were used to investigate electrooxidation of methanol and electrocatalytic activity of prepared electrocatalysts. The results showed that PtRu/C electrocatalyst has better activity in methanol condition due to its smaller average particle size of nanoparticles, superior activity for methanol oxidation and its higher carbon monoxide (CO) tolerance. The single DMFC cell consisted of protected electrocatalysts exhibited a 28 % increase in the peak power density in room temperature, with the maximum peak power density of 22.13 mW cm-2.

In this study PtFeCo ternary alloys nanoparticles of three dimentional (3D) rhombus shapes dispersed on graphene nanosheets (PtFeCo/Gr) were successfully prepared and studied as electrocatalysts for oxygen reduction reaction (ORR) in polymer-electrolyte fuel cells. A combination of analytical techniques including powder X-ray diffraction, X-ray photoelectron spectra, inductively coupled plasma-atomic emission spectrometry, scanning electron microscopy and electrochemical methods have been used for characterization of the synthesized electrocatalysts in this study. For comparison, the graphene supported PtFe catalyst (PtFe/Gr), graphene supported PtCo catalyst (PtCo/Gr) binary alloys and graphene supported Pt catalyst (Pt/Gr) were also synthesized and investigated under the same experimental conditions. From the electrochemical analysis, it is found that PtFeCo/Gr particles exhibited an obvious enhancement of ORR activity in comparison with pure Pt and binary alloys. The significantly improved EAS, ORR activity and cell performance is achieved by increasing the utilization of PtCoFe/Gr electrocatalyst by increasing the three-phase boundary in the electrocatalyst layer.

Proton exchange membrane fuel cells (PEMFCs) are electrochemical devices that show the highest power densities compared to the other type of fuel cell. In this work, nanocomposite membranes used for proton exchange membrane fuel cells as poly(vinyl alcohol)/La2Ce2O7 (PVA-LC) with the aim of increasing the water uptake and proton conductivity. Glutaraldehyde (GA) was used as cross linking agent of PVA matrix. PVA-LC nanocomposite membranes have been prepared with solutions casting method. The significant improvement has been achieved via the synergetic combination of organic and inorganic phases. Nanocomposite membranes were structurally, morphologically and electrochemically considered by FTIR, SEM and ELS, respectively. The results exhibited that the proton conductivity and the water uptake of the nanocomposite membranes were higher than that of the PVA membrane. PVA-LC nanocomposite membranes containing 4 wt.% of La2Ce2O7 nanoparticles displayed a high proton conductivity (0.019 S/cm). The highest peak power density of the PEMFC using PVA-LC nanocomposite membrane at ambient temperature was 19 mW/cm2. The proposed PVA-LC nanocomposite membranes appear to be a viable candidate for future PEMFCs applications.

This study presents a comparative investigation of two dimensionally stable anodes (DSA®) of nominal composition Ti/Ru0.3Ti0.7O2 and Ti/Ir0.3Ti0.7O2, prepared by thermal decomposition at high temperature. The materials were studied by scanning electron microscopy (SEM), cyclic voltammetry and Tafel measurements to obtain informations about their surface and electrocatalytic properties towards O2 evolution reaction. The stability of the samples was investigated under accelerated conditions. It has been observed that the coating surface with 30% mole IrO2 possesses more rough structure with less cracks. Furthermore, it had excellent electrocatalytic activity for the oxygen evolution. Accelerated stability tests showed long lifetime for Ti/Ir0.3Ti0.7O2 electrode. On the other hand, besides the excellent improvement of catalytic activity, the stability of the Ir containing electrode increases compared to the Ru containing one.

A controllable synthesis of flower-like lithium iron phosphate LiFePO4 (LFP) was obtained via a two-stage heating during hydrothermal process. In the first stage, the temperature was held at 105 °C (LFP1), 120 °C (LFP2), 150 °C (LFP3) and 190 °C (LFP4) for 5 h. In the final stage, the temperature was held constant at 400 °C under H2/N2 atmosphere for 4 h. To increase the electrochemical reversibility and electronic conductivity, LFP is treated with polyethylene glycol (PEG) as the templating agent and carbon sources forthe as-prepared materials. This is to obtain a modified LFP cathode with optimum electricalcontact between the electroactive materials and the carbon-filled electrode matrix which is found to be effective in terms of raising the electrochemical performance of the Li-ionbatteries. Results show that as the first-stage temperature increased, the correspondingelectrochemical performance of the resulting sample has been increased up to a temperature of 150 °C. Galvanostatic charge-discharge test indicates that flower-like LiFePO4/C composite, LFP3, exhibits initial discharge capacity of 118 mAh g-1 at 0.1C rates. The performance improvement was attributed to a reduction of the thickness and particle size of the flower-like LiFePO4 particles. Results of X-ray diffraction (XRD) revealed that the structure of the latter represents phase of the ordered olivine structure without any impurities. Cyclic voltammetry indicates that the improvement in redox cycling could be attributed to an increase of the electrochemical active surface area (ECSA) and the related increase in microporosity as evidenced by SEM analysis.

PVA (poly vinyl alcohol)-MnTiO3 (PM) and PVA-PVP (poly vinyl pyrrolidone)-MnTiO3 (PPM) nanocomposite membranes have been prepared with solutions casting method. Glutaraldehyde (GA) was used as cross linking agent. The results showed that the proton conductivity and water uptake of the nanocomposite membranes due to hydrophilic nature of MnTiO3 nanoparticles were higher than that of the PVA membrane. PPM membranes containing 5 wt. % of MnTiO3nanoparticles and PVA:PVP 80:20, demonstrated higher thermal stability, water uptake (310?) and proton conductivity (2.1 ×10 2 S/cm) than PM membranes, due to hydrophilic effect of PVP, which can made strong hydrogen-bonding, intense intra-molecular interaction and reduce the crystallinity of the PVA polymer.

Sulfonated polymer/silica hybrid nanoparticles were prepared by free radical polymerization of 2-acrylamido-2-methyl-1-propane sulfonic acid (PAMPS-g-SN) and styrene sulfonic acid sodium salt (PSSA-g-SN), initiated on the surfaces of aminopropyl-functionalized silica nanoparticles (ASN). Ce(IV) ammonium nitrate/nitric acid and sodium dodecyl sulfate were used as redox initiator and stabilizer, respectively. ASN Nanoparticles were synthesized by a covalently attached 3-aminopropyltriethoxysilane onto the surface of silica nanoparticles. Sulfonated monomers (AMPS or SSA) were then grafted onto the ASN nanoparticles, ultrasonically dispersed in water, using redox initiator system at 40 °C. ASN, PAMPS-g-SN and PSSA-g-SN nanoparticles were characterized by Fourier transform infrared (FTIR), thermogravimetry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. FTIR and TGA results indicated that both AMPS and SSA monomers were successfully grafted onto the silica nanoparticles. The grafted amounts of sulfonated polymers onto the silica nanoparticles were estimated from TGA thermograms to be 46 and 22 % for PAMPS and PSSA, respectively. From SEM and TEM micrographs, the average-diameters of the polymer-grafted silica nanoparticles were measured to be <50 nm with a (semi)spherical morphology, in which several silica nanoparticles were able to form a core with PAMPS or PSSA existing around the silica nanoparticles.