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Over the past years, lithium-ion solid-state batteries have demonstrated significant advancements regarding such properties as safety, long-term endurance, and energy density. Solid-state electrolytes based on lithium halides offer new opportunities due to their unique features such as a broad electrochemical stability window, high lithium-ion conductivity, and elasticity at close to melting point temperatures that could enhance lithium-ion transport at interfaces. A comparative study of lithium indium halide (Li3InCl6) electrolytes synthesized through a mechano-thermal method with varying optimization parameters revealed a significant effect of temperature and pressure on lithium-ion transport. An analysis of Electrochemical Impedance Spectroscopy (EIS) data within the temperature range of 25–100 °C revealed that the optimized Li3InCl6 electrolyte reveals high ionic conductivity, reaching 1.0 mS cm−1 at room temperature. Herein, we present the utilization of in situ/operando X-ray Photoelectron Spectroscopy (XPS) and in situ X-ray powder diffraction (XRD) to investigate the temperature-dependent behavior of the Li3InCl6 electrolyte. Confirmed by these methods, significant changes in the Li3InCl6 ionic conductivity at 70 °C were observed due to phase transformation. The observed behavior provides critical information for practical applications of the Li3InCl6 solid-state electrolyte in a broad temperature range, contributing to the enhancement of lithium-ion solid-state batteries through their improved morphology, chemical interactions, and structural integrity. [ABSTRACT FROM AUTHOR]

Lithium metal is recognized as the anticipated anode for rechargeable batteries because of its inherent physicochemical properties. Unfortunately, the industrialization of Li metal anodes (LMAs) has been entangled in some intractable problems stemming from the uncontrollable growth of Li dendrites, which could result in the issue of short-circuit, thereby leading to cell failure. Here, a three-dimensional structured Cu pyramid array (CPA@CF) is constructed on planar Cu foil (CF) by the simple electrodeposition method. Owing to the features of large surface area and 3D porous structure, the proposed CPA@CF not only can promote Li-ion diffusion and charge transfer, but also effectively slow down the volume change of Li. Consequently, an even and steady Li plating/stripping process up to 360 h is realized using such a CPA@CF current collector. The Li@CPA@CF|LiFePO4 full cell achieves an excellent Coulombic efficiency (CE) of 99.3 % for 160 cycles at 0.3 C with a superior capacity retention of 84.2 %. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal is perceived as the "holy grail" of anodes for secondary batteries due to its innate merits. Regrettably, the commercial application of Li metal anodes (LMAs) has been hampered by problems derived from the uncontrollable growth of Li dendrites, which could result in formation of short-circuits, thereby leading to fatal safety accidents. Here, a three-dimensional lithiophilic gold (Au)-coated copper (Cu) pentagonal pyramid array (Au@CuPPA) is constructed on planar Cu foil via electrodeposition followed by a chemical reduction method. Owing to the features of the lithiophilic layer and 3D porous structure, the proposed Au@CuPPA can not only facilitate Li-ion migration and charge transfer, but also effectively diminish the nucleation overpotential. Consequently, an even and steady Li plating/stripping process for up to 460 h and with a charge capacity of 3 mAh cm−2 is accomplished by using the Au@CuPPA current collector. The Li@Au@CuPPA|LiFePO4 full cell achieves a high Coulombic efficiency (CE) of 99.4% for 150 cycles at 0.5 C with a capacity retention of 92.4%. [ABSTRACT FROM AUTHOR]

The aerobic-enzymatic decomposition of alkali lignin in the presence of laccase from Trametes versicolor (LTV) and the natural mediator methyl syringate in acetic acid–sodium acetate buffer solution (pH = 4.5) at 40 °C in an oxygen-rich (aerobic) environment is studied. SEM and BET analyses are used to characterize the changes in the surface area and morphology of lignin that occurred during the exposure to the laccase–mediator system (LMS) for 72 h. The LMS interaction causes a 2-fold improvement in the surface area from 4.9 to 9.8 m2 g−1, due to significant changes in the mesoporous structure of lignin within a pore size of 2–120 nm. This could be due to an efficient interaction of the surface phenolic groups and internal mesoporous β-O-4 network of lignin with the LMS in an aerobic environment. To further understand the enzymatic degradation of lignin, electrochemical oxidation of a thin film of lignin on the surface of a glassy carbon electrode (GCE) is performed under aerobic vs. anaerobic conditions in the presence of the LMS. A synergistic lignin electrooxidation in the aerobic environment is observed due to the promotion of LMS activity by a parallel oxygen reduction reaction (ORR). Based on the electrochemical studies, a mechanism for understanding the role of oxygen in the enzymatic oxidation of lignin in an aerobic environment and the stability of the mediator radical (MSṖ) is proposed. [ABSTRACT FROM AUTHOR]

A comparative study between a nonconductive thermoplastic, polyacrylic acid (PAA), and an electronic-conducting polymer, polyaniline (PANI), has been conducted related to their function as binders for Silicon Nanoparticle (SiNP)-based anodes in Li-ion battery application. SEM analysis was used to understand the morphological differences associated with dispersion of PAA/PANI with SiNPs. Further, thermogravimetric analysis was conducted in order to understand the thermal degradation and to choose their associated heat-treatment temperatures of 400 °C (PAA) and 300 °C (PANI). Te electrochemical performance of the resultant silicon-based electrodes assembled in Lithium-half-cell configuration was evaluated in terms of their specific capacitance and cycle-stability. The results indicated that PANI-based SiNP anodes heat-treated at 300 °C demonstrate the highest specific capacitance and the lowest capacity loss over 10 cycles, which could be attributed to higher electrical conductivity and improved adhesion. [ABSTRACT FROM AUTHOR]

Mixed ionic−electronic conducting nanocomposites comprising complex oxides - perovskite (lanthanum-strontium nickelate-ferrite [LSFN]) and gadolinium-doped ceria (GDC) have been prepared via ultrasonic dispersion of nanocrystalline powders of LSFNxand GDC in organic solvent with addition of surfactant, followed by drying and sintering up to 1300°C. Their structural and surface properties have been studied by x-ray diffraction, ultraviolet–visible (UV-vis) electron spectroscopy, transmission electron microscopy with elemental analysis, and x-ray photoelectron spectroscopy. Results of impedance spectroscopy, oxygen isotope exchange, O2temperature-programmed desorption, weight, and conductivity relaxation experiments have revealed a strong positive effect of perovskite−fluorite nanodomain interfaces in composite on the oxygen mobility and reactivity. Testing in wet H2/air feeds for a button-size cell with functionally graded LSFN0.4–GDC cathode layer supported on a thin YSZ layer covering Ni/YSZ cermet has demonstrated high and stable performance, promising for the practical application in the intermediate temperature range. [ABSTRACT FROM AUTHOR]

Mixed ionic–electronic conducting nanocomposite La0.8Sr0.2Ni0.4Fe0.6O3 (LSNF)–Ce0.8Gd0.2O2–δ (GDC) was prepared via ultrasonic dispersion of nanocrystalline powders of perovskite and fluorite oxides in water with addition of surfactant, followed by drying and sintering up to 1300°C. Analysis of the real structure of nanocomposite (studied by XRD and TEM with EDX) and its surface composition (studied by XPS) revealed moderate redistribution of elements between phases favoring their epitaxy. Results of impedance spectroscopy, oxygen isotope exchange, O2 TPD and H2 TPR experiments revealed a positive effect of composite interfaces on the oxygen mobility and reactivity agreeing with the ambipolar transport behavior of MIEC composite. Preliminary testing of button-size cell with functionally graded LSNF–GDC cathode layer supported on thin YSZ layer covering Ni/YSZ cermet demonstrated high and stable performance, which is promising for its practical application. [ABSTRACT FROM AUTHOR]

In this study, supercritical carbon dioxide (scCO2) deposition was used to prepare vulcan-supported Pt (Pt/Vulcan) electrocatalysts for proton exchange membrane fuel cells (PEMFCs), and the effects of process variables on the properties of the electrocatalysts were investigated. The two different methods used to reduce the organometallic precursor were thermal reduction in nitrogen at atmospheric pressure and thermal reduction in scCO2. In the former method, the maximum Pt loading achieved was 9%, and this was governed by the adsorption isotherm of the Pt precursor between the scCO2 phase and the Vulcan phase. By using the latter method, higher Pt loadings of 15% and 35% could be achieved. The Pt/Vulcan catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and cyclic voltammetry (CV). The average particle sizes for Pt/Vulcan 9%, 15%, and 35% catalysts were 1.2, 1.3, and 2 nm, respectively. Electrochemical surface areas obtained from CV data were found to vary with the Pt loading. [ABSTRACT FROM AUTHOR]

Initiated enzyme-catalyzed and mediator-facilitated radical reactions of degradation lead to formation of both phenolic and non-phenolic aromatic structures. A laccase should have broad substrate compatibility and high redox potential and be tolerant to deactivation in the presence of a mediator. Unfortunately at present, there is no "universal" laccase that fulfils all the above criteria. The objective of this work is to characterize two specific systems for enzymatic degradation of lignin, including two types of commercially available lignin (Indulin AT and Alkali lignin) with Myceliophthora thermophila laccase enzyme and a mediator (Methyl syringate). Laccase (Novozymes, 22127) activity was determined by oxidation with diluted 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) in H2O. The activity of the original laccase was 326 U/ml in aqueous solution. The lignin treatment was carried out by the laccase-mediator (1% -1%) system at 50 °C by using 2.23g lignin samples at 6% consistency (w:w) in 50 mM sodium dihydrogen phosphate (pH 6.5) under an O2 atmosphere for 72 h. Electrochemical study of the LMS in buffer solution, Na2HPO4 -NaH2PO4 with pH = 6.5, was conducted to evaluate the role of laccase in promoting the mediator for selective oxidation of lignin. An SEM analysis revealed the changes in surface morphology associated with indulin and alkali lignin before and after the LMS treatment. A Brunauer-Emmett-Theller (BET) analysis of two types of lignin, specifically alkali lignin and indulin lignin, have been conducted before and after contact with the laccase mediator system (LMS). This work is supported by the National Science Foundation EPSCOR Cooperative Agreement #IIA-1330842 BIOCON project. [ABSTRACT FROM AUTHOR]

The results of liquefaction of lignin in sub- and supercritical conditions in a temperature range of 200-500 °C at 3200 psi are reported. After hydrothermal treatment, the organic phase separated by liquid-liquid extraction was characterized by GC-MS and TOC (total organic carbon) approaches. The solid phase was analyzed by a GC-MS 2010 Schimadzu pyrolyzer. Among a number of phenolic products (e.g. o-guaiacol, p-guaiacol, methylguaiacol, and vanillin), o-guaiacol had the highest relative percentage yield of 39.69% and 37.91% in presence of CO2 and N2 at 400 °C. It was confirmed by the TOC test that the percentage of carbon evolved (40.3%) was highest at 300 °C when the lignin was treated with CO2. The presence of phenolic products in the solid phase obtained after the hydrothermal treatment of lignin also has been confirmed by GC-MS pyrolysis. [ABSTRACT FROM AUTHOR]

The present study is focused on enhancing the rheological properties of the electrolyte and eliminating sedimentation of microorganisms/flocs without affecting the electron transfer kinetics for improved bioelectricity generation. Agar derived from polysaccharide agarose (0.05–0.2%, w/v) was chosen as a rheology modifying agent. Electroanalytical investigations showed that electrolytes modified with 0.15% agar display a nine-fold increase in current density (1.2 mA/cm 2 ) by a thermophilic strain ( Geobacillus sp. 44C, 60 °C) when compared with the control. Sodium phosphate buffer (0.1 M, pH 7) electrolyte with riboflavin (0.1 mM) was used as the control. Electrolytes modified with 0.15% agar significantly improved chemical oxygen demand removal rates. This developed electrolyte will aid in improving bioelectricity generation in Bioelectrochemical Systems (BES). The developed strategy avoids the use of peristaltic pumps and magnetic stirrers, thereby improving the energy efficiency of the process. [ABSTRACT FROM AUTHOR]

Abstract Located in the north of Tajikistan, the Koni Mansur is a rich polymetallic deposit that besides other metals has high concentration of lead-containing mineral galena. The hydro metallurgical extraction of lead from the Koni Mansur lead sulfide (galena) mineral in acidic media, its chemical composition and morphological properties in comparison to the Balya deposit in Turkey are reported for the first time. Energy dispersive X-ray fluorescence spectrometry was applied for chemical analysis of galena, while mineralogical characterization before and after lead acidic extraction was performed by XRD. The nitric acid concentration, temperature, duration of the extraction process, and the particle size distribution before and after extraction have been evaluated. The amount of lead in solution after extraction and solid-liquid phase separation was determined by the flame atomic absorption spectroscopy (FAAS). The particle size distribution before and after lead extraction revealed no significant changes. Assuming spherical shape of the particles, the Shrinking Core Model (SCM) used for kinetic study of the lead extraction allowed to define the activation energies and changes in the corresponding reaction mechanisms. Specifically, the activation energy at 293-318 K (12.4 kJ/mol) was significantly lower than at higher temperatures (318–338 K) reaching ~46.778 kJ/mol which indicates the corresponding change in the extraction mechanism. Highlights • Galena concentrate from Koni Mansur deposit studied for the first time. • Shrinking Core Model for kinetic study of lead extraction has been validated. • The study confirms mixed reaction mechanism for the extraction process. [ABSTRACT FROM AUTHOR]

A novel circulation type a hydrogen generator operating on sodium borohydride – sodium borate solution has been developed. The major parameters, such as operation temperature, concentration of the sodium borohydride and metaborate, catalytic activity, start up conditions, and removal of NaBO 2 as a product of the sodium borohydride hydrolysis have been analyzed. Generation of hydrogen was evaluated for aqueous NaBH 4 solutions in the range of 15–23 wt. % NaBH 4 in presence of the alumina supported Pt, Pd, Rh and Ni catalysts. The main trends in hydrogen gas generation with respect to the solution temperature and pressure in the reactor were analyzed. The catalytic efficiency and the rate of the hydrogen gas generation (1.5 Nm 3 /h) at the average hydrogen yield of 97–98.5% is sufficient for operation of the PEMFC Nexa™ Power module from Ballard. [ABSTRACT FROM AUTHOR]

The present study ellucidates bi-functional catalytic activity of the graphene-supported praseodymium (PrNi x Co 1-x O 3-δ) and samarium (SmNi x Co 1-x O 3-δ) perovskites towards oxygen evolution and oxygen reduction reactions in alkaline solutions. The perovskites with varied Ni and Co content (of x = 0.1, 0.5, and 0.9) were synthesized via sol-gel glycine-nitrite combustion followed by heat-treated at 700, 900 and 1200 °C. The cubic perovskite phase of PrNi x Co 1-x O 3-δ was stabilized at x = 0.1, 0.5 in the entire temperature range (of 700 °C–1200 °C), while the perovskite phase of SmNi x Co 1-x O 3-δ (x = 0.1, 0.5) was observed only at lower temperatures (of 700 and 900 °C). Consequently, changes in structural properties resulted in superior oxygen evolution reaction (OER) electrochemical activity in comparison to the state-of-the-art IrO 2. Among the Sm-based perovskites, SmNi 0.1 Co 0.9 O 3-δ (700 °C) demonstrated OER mass activity of 495 mA/mg and the highest oxygen reduction reaction (ORR) activity of 95 mA/cm2·mg. For Pr-based perovskites, the highest electrocatalytic activity toward OER and ORR was observed for PrNi 0.1 Co 0.9 O 3-δ (900 °C) resulting in 60 mA/mg for ORR and 680 mA/mg for OER which is 50% higher than the mass activity of the state-of-the-art IrO 2 catalyst. The overall performance of the composites is discussed in terms of graphene support interactions, Co and Ni redox processes, relative concentration of oxygen-vacancy sites and OER/ORR bi-functionality. Image 1 • Praseodymium and samarium-based perovskites were synthesized. • Catalytic activity towards OER and ORR is observed in alkaline media. • OER/ORR bi-functionality is described through graphene support-catalyst interaction. [ABSTRACT FROM AUTHOR]

A hierarchical mesoporous carbon foam (ECF) with an interconnected micro-/mesoporous architecture was prepared and used as a binder-free, low-cost, high-performance anode for lithium ion batteries. Due to its high specific surface area (980.6 m 2 /g), high porosity (99.6%), light weight (5 mg/cm 3 ) and narrow pore size distribution (~2 to 5 nm), the ECF anode exhibited a high reversible specific capacity of 455 mAh/g. Experimental results also demonstrated that the anode thickness significantly influence the specific capacity of the battery. Meanwhile, the ECF anode retained a high rate performance and an excellent cycling performance approaching 100% of its initial capacity over 300 cycles at 0.1 A/g. In addition, no binders, carbon additives or current collectors are added to the ECF based cells that will increase the total weight of devices. The high electrochemical performance was mainly attributed to the combined favorable hierarchical structures which can facilitate the Li + accessibility and also enable the fast diffusion of electron into the electrode during the charge and discharge process. The synthesis process used to make this elastic carbon foam is readily scalable to industrial applications in energy storage devices such as li-ion battery and supercapacitor.