Raman scattering and calorimetric measurements on lithium borate, (Li2O)(x)(B2O3)(100-x), and sodium borate, (Na2O)(x)(B2O3)(100-x), glasses, 0 < x < 45 %, were undertaken to elucidate the role of glass molecular structure on the topological phases and melt dynamics. For (Na2O)(x)(B2O3)(100-x) glasses, a wide square-well like variation of the enthalpy of relaxation at the glass transition was observed, showing an intermediate phase (IP) in the 20 % < x < 40 % range of soda. Raman results reveal the IP to be correlated with the existence of six unique Isostatically Rigid Local Structures (ISRLSs) which have characteristic ring morphologies appearing sequentially with increasing soda concentration across the IP. Additionally, several narrowly defined Gaussian-like fragility index, m, minima are observed to manifest in the 15 < m < 20 range, which appear sequentially with increasing mol x% and directly correspond to the stoichiometry of the six molecular ring based ISRLS. Parallel results are observed for (Li2O)(x)(B2O3)(100-x).

This study investigates hydrogen and air or O-2 oxidant starvation in proton exchange membrane fuel cells for accelerating the break-in process, which is beneficial for industrial manufacturing by reducing hydrogen consumption and conditioning time. The gas starvation method was conducted at 60 and 70 degrees C to enhance electrochemical reactions and expand the triple-phase region, reducing conditioning time. Fuel cell performance before and after gas starvation is evaluated, showing increased voltage at all current densities with H-2/Air (400 mW cm(-2) at 0.6 V and H-2/O-2 (790 mW cm(-2) at 0.6 V) after 5 and 2 h, respectively. The process improves electrolyte humidification, removes impurities, and reduces contact resistance. Electrochemical tests such as H-2 crossover and impedance spectroscopy confirm that gas starvation had no severe impact on membrane integrity, with H-2 crossover well below 5 mA cm(-2). A 2(2) factorial optimization reveals that low temperature and high humidity with Nafion membrane (thickness: 18 mu m) yields a peak power density of similar to 600 mW cm(2), without any back pressure.

This study deals with various flow field designs for anode, cathode and coolant plates for optimizing the performance of proton exchange membrane fuel cell using H2 and air. In particular, the 3D models with various flow field patterns such as single parallel serpentine (anode), multi parallel (anode), multi-parallel serpentine (cathode), multi serpentine (cathode) have been evaluated for enhancing the fuel cell performance at 60 degrees C, with three different coolant flow designs (mirror serpentine, multi serpentine and parallel serpentine). Both the peak power and limiting current density are considered based on the parameters such as temperature distribution, pressure distribution, reactants/species distribution and the membrane water content on the active area (50 cm2) region. It is interesting to note that the coolant channel also has a significant effect in regulating the fuel cell performance at high current densities, in addition to reactant gas flow channels. The simulated single cell with Nafion (thickness: 18 mu m) demonstrates a peak power density of 0.97 W cm(-2) with single parallel serpentine (anode), multi parallel serpentine (cathode) and serpentine (coolant) and 0.91 W cm(-2) with multi parallel (anode), multi serpentine (cathode), and parallel serpentine (coolant) flow field designs. The simulated fuel cell performance is also experimentally validated at 60 degrees C using H-2 fuel and air as the oxidant.

Prices of lithium raw materials keep on increasing exponentially due to their heavy consumption for lithium batteries used in portable electronic devices as well as automobiles. Also, the global lithium deposits are very limited. Hence, sodium-ion batteries (SIBs) have been heavily investigated as cheaper alternatives to expensive lithium-ion batteries, mainly due to the abundance of sodium raw materials. However, one of the major bottlenecks faced by the material research community to commercialize SIBs is the poor ionic conductivity of sodium-ion conducting electrolytes at ambient temperature, especially in the solid-state. Very recently, quasi-solid state polymer electrolytes (QSSPEs) have been proposed to overcome this challenge. In this work, a set of QSSPEs have been synthesized by using poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) host polymer and NaBF4 ionic salt dissolved in EC/PC plasticizer/solvent mixture. The highest conducting composition; 6 PVdF-HFP: 14 NaBF4: 40 EC: 40 PC (wt.%); showed an ambient temperature ionic conductivity of 4.1x10-3 S cm-1. The activation energy is almost same for all the sample compositions studied in this work suggesting that the activation process is mainly controlled by EC/PC. DC polarization test on highest conducting electrolyte composition with a configuration of SS/QSSPE/SS revealed that the electrolyte is predominantly ionic conductor with negligible electronic conductivity; a much desired property for a good electrolyte. Linear sweep voltammetric studies confirmed that the electrochemical stability window of the highest conducting electrolyte is about 3.6 V. This highest conducting electrolyte composition is found to be highly suitable for practical applications in sodium batteries.

Synthesis of materials to harvest photon energy together with mechanical energy beneficial to address the current energy shortage and enhance the photocatalytic properties of the material. Bare ZnO displays poor photocatalytic properties under visible light illumination owing to higher bandgap energy. Intrinsic defect engineering of ZnO lattice by Al doping enhance the visible light harvesting ability and the better piezo-electric properties contribute additional electron in the lattice would upsurge the piezo-photocatalytic property under the visible region. Aluminum doped in ZnO lattice prepared by two-step sintering method in which the Al doped ZnO (AZO) sintered at 150 degrees C for one hour and followed by 500 degrees C for two hours. The enhanced piezo-photocatalytic properties verified based on the piezo-photocatalytic degradation of Methylene blue dye under visible light together with mechanical vibration. The enhanced piezo-photo-catalytic activity attributed to enhanced visible light harvesting via defects in the lattice, freely existence of electron in the AZO lattice, enhanced surface area and zinc/oxygen vacancies in the lattice. The AZO shows better piezo-photocatalytic properties and almost 53.7% enhanced piezo-photocatalytic efficiency than the bare ZnO under the visible light illumination. This work highlights the attractive piezo-photocatalytic properties of 10% Al-doped ZnO (AZO-10) via strong coupling of visible light harvesting and piezoelectricity to convert both photon and mechanical energy into chemical energy.(c) 2023 Elsevier B.V. All rights reserved.

Phenol is one of the most prevalent contaminants discovered in water bodies. The adsorption process is gaining popularity as a viable method of removing phenolic chemicals from contaminated aquatic resources. The elimination of phenolic chemicals using Palmyra kernel shell activated charcoal has been extensively investigated. The removal effectiveness of Palmyra kernel shell charcoal was calculated using physically, chemically (H3PO4 and NaOH) and magnetically activated Palmyra kernel shell charcoal for various amounts of phenolic components and varying adsorption durations. According to this research study, physically activated charcoal has a much higher removal efficiency than other activated charcoal. These findings show that physically activated charcoal is easily used to remove phenolic compounds from polluted water resources. Adsorption kinetics were discovered to follow a pseudo-second-order kinetic model. Freundlich, Langmuir, and Temkin isotherm models were used to interpret the experimental results. Several kinetic formulas were utilized to evaluate the adsorption kinetics of phenolic compounds using various activated charcoals derived from Palmyra kernel shells. The experimental results are consistent with the Freundlich isotherm model. All of the activated and non-activated Palmyra kernel shells absorbed the phenolic chemicals, and the value of 1/n was found to be between 0.692 to 0.869. Scanning Electron Microscopy (SEM) is a technique used to characterize the surface morphology of adsorbents before and after adsorption. FTIR analyses confirmed the presence of phenolic compound functional groups on the adsorbents.

Research and development works in the field of multi-valent metal-ion batteries are intensified these days because of the abundance of multi-valent elements such as magnesium, aluminum, calcium and so on in the Earth’s crust. Magnesium-ion batteries are particularly important, because they have high theoretical volumetric capacity (3832 mAh cm-3) compared to that of well-known lithium-ion batteries (2062 mAh cm-3). However, there are potential challenges, typically, designing suitable electrolytes with sufficient ambient temperature ionic conductivities is a major challenge. In this work, a set of gel-polymer electrolytes based on poly (ethylene oxide) (PEO) host polymer and magnesium acetate (Mg(CH3COO)2) ionic salt have been synthesized and characterized by electrochemical impedance spectroscopy (EIS), DC polarization and linear sweep voltammetry (LSV) techniques. Among the compositions studied in this work, the optimized PEO-Mg(CH3COO)2-EC-PC electrolyte (6:14:40:40 wt.%) showed an ambient temperature ionic conductivity of 6.1x10-5 S cm-1. Ionic conductivity vs inverse temperature showed Arrhenius behavior with almost same activation energies (0.15 - 0.18 eV) for all the compositions. DC polarization studies performed with stainless steel blocking electrodes under an externally applied voltage of 1V showed that the highest conducting composition is dominantly an ionic conductor with an ionic transference number of 0.99. The electronic contribution to conductivity was found to be almost negligible, which is desirable to avoid short circuits within the cell. The LSV test on highest conducting composition revealed that the electrochemical stability window of these electrolytes is about 2.2 volts.

Global lithium deposits have been consumed a lot because of the heavy usage of lithium-ion batteries (LIBs) in almost all portable electronic devices and in automobiles. Due to the very limited global lithium resources, the so-called ‘batteries beyond lithium-ion’ such as sodium-ion batteries (SIBs) are becoming popular, particularly in the R&D level. One of the common problems in the commercial level production of SIBs is the synthesis of suitable electrolytes with sufficient ambient temperature ionic conductivities. In this work, a set of novel gel-polymer electrolytes (GPEs) based on poly (methyl methacrylate) (PMMA) host polymer have been synthesized and characterized by electrochemical impedance spectroscopic (EIS), DC polarization and cyclic voltammetric (CV) techniques. The optimized PMMA-NaClO4-EC-DMC GPE composition (10:14:38:38 wt.%) showed an ambient temperature ionic conductivity of 8.4 mS cm-1. Ionic conductivity vs inverse temperature showed Arrhenius behavior with almost same activation energies of 0.16 eV for all the compositions studied. DC polarization test on SS/GPE/SS configuration showed that the best conducting composition is dominantly an ionic conductor (tion ~ 0.998) with negligible electronic conductivity, which is highly desirable to avoid short circuits within the cell. The CV test on best conducting composition revealed that the electrochemical stability window (ESW) of these GPEs is about 4 volts (- 2 to + 2 volts). This optimized composition with highest ambient temperature ionic conductivity and negligible electronic conductivity seems to be a promising candidate for practical applications in sodium-ion secondary batteries.

In this work, the methanol oxidation reaction is investigated on Ni based metal organic frameworks (MOF) and its composites with biomass derived activated carbon. NiO-MOF and composites with activated carbon were synthesized using hydrothermal method. SEM, EDX, and XRD, FTIR, TGA techniques were used for characterization of composites. The electrochemical activity of catalysts for oxidation of methanol was tested using cyclic voltammetry (CV) in 1 M KOH and 3 M CH3OH on glassy carbon electrode in three electrode setup. The electrochemical performance shows the effect of activated carbon concentration on methanol oxidation. The electro-oxidation catalyzed by NiO-MOF with activated carbon (40 mg) composite exhibits a peak current density of 182.72 mA/cm2 at 0.89 V potential with a scan rate of 50 mV/s making it a potential catalyst for electrocatalysis of methanol.

The prime objective of the present study is to exploit a user friendly, inexpensive all solid state super capacitor using a suitable electrolyte and electrodes. A gel polymer electrolyte (GPE) consisted with polyvinylidene fluoride-co-hexafluopropylene (PVdF), ethylene carbonate (EC), propylene carbonate (PC) and zinc trifluoromethane sulfonate (Zn(CF3SO3)2-ZnTF) was prepared using solvent casting method and its properties were optimized by varying the composition. The composition of 16 PVdF : 22 ZnTF : 31 EC : 31 PC (weight %) exhibits the optimum room temperature conductivity of 3.09 × 10-3 Scm-1. It is purely an ionic conductor having a negligible electronic conductivity. In addition, it was possible to obtain a thin, mechanically stable film. The electrodes were prepared using Sri Lankan natural graphite (NG) with a polymer binder. Eventhough there are reports about natural graphite based super capacitors, Sri Lankan natural graphite has not been considered for super capacitors at a large scale. The main reason for turning towards natural graphite is to reap the benefits of low cost as well as the safety. In order to optimize the electrode properties, the ratio between graphite and polymer binder (in weight basis) was changed. The polymer binder used was polytetrafluoroethylene (PTFE). Super capacitor fabricated with the electrode of the composition, NG : PTFE = 90:10 shows the maximum single electrode specific capacitance (2.58 Fg-1). The fabricated device retains for continuous charge discharge operation with a minimum performance reduction.

Metal-organic frameworks (MOFs) with efficient surface and structural properties have risen as a distinctive class of porous materials through the last few decades, which has enabled MOFs to gain attention in a wide range of applications like drug delivery, gas separation and storage, catalysis and sensors. Likewise, they have also emerged as efficient active materials in energy storage devices owing to their remarkable conducting properties. Metal-organic frameworks (MOFs) have garnered great interest in high-energy-density rechargeable batteries and super-capacitors. Herein the study presents their expanding diversity, structures and chemical compositions which can be tuned at the molecular level. It also aims to evaluate their inherently porous framework and how it facilitates electronic and ionic transportation through the charging and discharging cycles of lithium-ion batteries. In this review we have summarized the various synthesis paths to achieve a particular metal-organic framework. This study focuses mainly on the implementation of metal-organic frameworks as efficient anode and cathode materials for lithium-ion batteries (LIBs) with an evaluation of their influence on cyclic stability and discharge capacity. For this purpose, a brief assessment is made of recent developments in metal-organic frameworks as anode or cathode materials for lithium-ion batteries which would provide enlightenment in optimizing the reaction conditions for designing a MOF structure for the battery community and electrochemical energy storage applications.

Sodium-ion batteries are being heavily investigated as cheaper alternatives to expensive lithium-ion batteries. However, synthesizing suitable electrolytes with sufficient ambient temperature ionic conductivities is a major bottleneck. In this work, gel-polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) host polymer and NaClO4 ionic salt are developed by using ethylene carbonate (EC) and propylene carbonate (PC) plasticizer/solvent mixture. The optimized PEO:NaClO4:EC:PC composition (7:13:40:40 wt%) exhibits an ambient temperature ionic conductivity of 9.5 mS cm(-1) and the variation of ionic conductivity with inverse temperature showed Arrhenius behavior with almost same activation energies for all the compositions. DC polarization studies on optimized composition reveals that the electrolyte is dominantly an ionic conductor (t(i) = 0.99) with negligible electronic conductivity (t(e) = 0.01), which is highly desirable for an effective electrolyte. Cyclic voltammetric and linear sweep voltammetric studies confirm that the optimized composition is electrochemically stable for a voltage window of 1.85 to +1.85 V. Absence of any crystalline peaks in the X-ray diffractograms of the GPEs is a clear evidence for the amorphous nature of these GPEs. Broadening of the FTIR vibrational bands at 1000-1300 and 1700-1850 cm(-1) is ascribed to the lowering of crystallinity resulting from the formation of PEO/Na+ complex through Na+ ion solvation by the polymer host. The GPE with optimized composition and highest ionic conductivity at ambient temperature is a suitable electrolyte for practical applications in sodium-ion batteries.

A series of highly efficient quasi-solid-state dye-sensitized solar cells (DSCs) is prepared by harnessing the binary cation effect and positive effects of the selected performance enhancers of gel-polymer electrolytes. The new electrolyte is composed of polyacrylonitrile polymer, tetra-hexylammonium iodide (Hex4NI) and KI binary salts as well as 4-tertbutylpyridine and 1-butyl-3-methylimidazolium iodide performance enhancers. The charge transport in the series of electrolytes is thermally activated and, accordingly, the temperature dependence of conductivity follows the VTF behavior. The enhancement of conductivity is observed with an increasing mass fraction of KI and decreasing mass fraction of Hex4NI, while the total mass fraction of salts in the electrolyte is kept unchanged. The highest conductivity of 3.74 mS cm-1 at ambient temperature is shown by the sample containing KI only (without Hex4NI) at all the temperatures. The effects of dielectric polarization of the electrolytes are studied by analyzing the frequency dependence of the real and the imaginary parts of the AC conductivity in detail. Appropriate and reproducible cell construction are assured by efficiencies of above 5% exhibited by all the quasi-solid-state DSCs assembled using double-layered TiO2 photo-electrodes and the new electrolyte series. Besides, highlighting the mixed cation effect, the cells with mixed salts exhibited efficiencies greater than 6%. An impressively high efficiency of 7.36% was shown by the DSC prepared with electrolyte containing 75 wt% KI and 25 wt% Hex4NI. This study reveals that the salt combination of KI and Hex4NI, which has not been reported before, is a suitable binary iodide salt mixture to prepare highly efficient DSCs. The replacement of tetra-hexylammonium ions by K+ ions improves the charge transport in the electrolyte; however, the best solar cell performance is shown by the mixed salt system with 75 wt% KI and 25 wt% Hex4NI, which is not the highest conductivity composition. Therefore, the exhibited high efficiency of 7.36% is evidently due to the binary cation effect.

The voltammetric hysteresis visible in current density versus solar cell potential (J-V) curves is a serious concern because it is known that the performance of Dye-sensitized Solar Cells (DSCs) depends on the direction of the potential and the rate of scan. J-V characteristics of gel electrolyte based DSCs were obtained by varying the scan rate from 0.01 to 0.1 V s^-1 and the direction from forward bias to reverse bias and reverse bias to forward bias. Three electrolytes were tested, two of them were 100% single salt electrolytes of KI and Hex_4NI, and the other was a mixed salt electrolyte containing KI (75%) and Hex_4NI (25%). DSC containing mixed salts electrolyte exhibited higher efficiency than single salt electrolytes. The energy conversion efficiency with mixed salts increased from 5.9 to 6.4% with the increase of the scan rate from 0.01 to 0.1 V s^-1, when the scanning was conducted from forward bias to reverse bias direction. However, when the scanning was carried out with revised polarity a drop of the efficiency was observed with increasing rate of potential scan. Present work emphasizes the importance of reporting the rate and direction of potential scan along with solar cell performance parameters.

•This review deals with organic, inorganic and eutectic phase change materials.•Future research trends for commercializing phase change materials are brought out.•Melting point, temperature range, thermal conductivity, energy density, etc. are discussed.

Ever growing high concerns over use of safe and low cost devices have provided a substantial attention on natural materials. As such natural graphite which has been deeply integrated into numerous applications is being received a consideration to be used for electrochemical devices. The main objective of this study is to explore the suitability of Sri Lankan natural graphite to serve in electrochemical double layer capacitors (EDLCs). In order to uplift the safety of the device, a gel polymer electrolyte was used instead of a liquid electrolyte. Two identical electrodes were consisted with Sri Lankan natural graphite as the active material and polyvinylidenefluoride as the binder. To prepare the electrolyte, polyvinylidenefluoride co hexafluoropropylene and magnesium perchlorate were used as the polymer and the salt respectively. Cyclic voltammetry test results show that single electrode specific capacitance is depending on the potential window. The percentage reduction of capacitance with continuous cycling was about 28%. Nyquist plot of EDLC further confirm the capacitive nature at low frequency.

Research and development activities on sodium-ion batteries are becoming prominent in the past few years. Compared to lithium-based batteries, the sodium-based batteries will be cheaper because of the abundancy of sodium raw materials in the earth’s crust and also in seawater. In the current study, we synthesized and characterized poly-acrylonitrile (PAN)-based gel-polymer electrolytes formed with NaClO4 and dissolved in ethylene carbonate (EC) and propylene carbonate (PC). By systematically varying the weight ratios of polymer, salt, and the solvents, we obtained an optimum room temperature ionic conductivity of 4.5 mS cm−1 for the composition 11PAN-12NaClO4-40EC-37PC (wt.%), which is reasonably good for practical applications. This value of conductivity is comparable to a few other Na+ ion conducting gel-polymer electrolyte systems studied in the recent past. Variation of ionic conductivity with inverse temperature showed Arrhenius behavior. Activation energies estimated for all the samples showed only a slight variation suggesting that a single activation process which depends on the EC/PC co-solvent governs the ionic mobility in these gel-polymer electrolytes. Thermo-gravimetric analysis (TGA) revealed that there is no noticeable weight loss of these electrolytes up to 100 °C and hence the electrolytes are thermally stable for operating temperatures up to 100 °C.

The fuel economy of 31 MPG (based on combined city and highway) and Environment labels are being affixed to new vehicles after 2013 model year, as mandated by the U.S. Environmental Protection Agency. Most of the fuel-efficient 2016 model year passenger cars are hybrid electric vehicles. Hybrids combine the best features of the internal combustion engine with an electric motor powered by batteries and can significantly improve fuel economy. Plug-in hybrids are plugged into wall outlet for battery recharging or driven by electric motor for relatively longer distance. The all-electric vehicles are propelled by electric motor powered using rechargeable battery packs, emitting no tailpipe pollutants. Among various battery technologies, Li-ion battery system is the more preferable one for the automotive applications due to their relatively higher energy density. This review examines various aspects of Li-ion batteries related to performance, durability, energy management and safety related to automotive applications. The review also discusses about the possibility of automotive Li-Ion batteries towards second life in stationary applications.