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Hydrogen can be used to sustain a revolutionary energy system, capable of integrating renewable sources and free from greenhouse gas emissions, in the perspective to mitigate global warming. Fuel cells and electrolyzers are the cornerstone of this new clean energy system, that is currently under research, development and implementation. [ABSTRACT FROM AUTHOR]

The article focuses on carbon nitride-based electrocatalysts for application in low-temperature fuel cells (FCs). Topics discussed include low-temperature fuel cells such as proton exchange membrane fuel cells (PEMFCs) and anion-exchange membrane fuel cells (AEMFCs), requirement of oxygen reduction reaction (ORR) electrocatalysts (ECs) to minimize cathode polarization losses and three dimensional (3D)-crosslinked hybrid macromolecular precursors.

Recent advancements in Vanadium Redox Flow Batteries (VRFBs) assert that their performance degradation and lack of charge retention is generally ascribed to the crossover of Vanadium species of the electrolytes through the Ion Exchange Membrane (IEM). In this report, a comprehensive electrochemical formalism is proposed to shed light on the role played by the equilibria and redox processes of the active Vanadium complexes in electrolytes in the modulation of the electrical behavior of an operating VRFB. This target is achieved by adopting the strategy to consider: a) the Vanadium species with the same oxidation state as a single ensemble of species; b) the redox processes as bridging events between the different ensembles of Vanadium species; and c) the correlations existing between chemical processes and the electrochemical status of a VRFB both in terms of potential and of self-discharge features. The developed formalism reveals the role played by the complex Vanadium coordination chemistry on the electrochemical performance of a VRFB. In detail, under Open Circuit Voltage (OCV) studies, VOH2+/V2+ and H 2 VO 4 −/VO2+ redox couples contribute negatively to the capacity retention of the device. During the charging process, VOH2+/V2+ and H 2 VO 4 −/VO2+ equilibria concur potentially for a decrease of the overall current density by up to 22% and 4.7%, respectively. Taken all together, the analyzed equilibria and the redox processes here proposed are not negligible in modulating the possible electrochemical loss of performance of a VRFB. Thus, these outcomes offer a different scenario to the widely accepted theory which considers to the crossover of active species through the ion-conducting membranes as the only one phenomenon responsible for the performance drop of these devices. Therefore, results here reported: (a) open the door for a systematic understanding of unforeseen phenomena which are potentially responsible for modulating the electrochemical performance loss of a VRFB; and (b) are a quantitative example of how to rationalize the behavior of a RFB, which is based on a complex chemistry. Finally, results shed light on a new scenario of phenomena that is necessary to master, in order to manage the operation of a VRFB and to improve its long-term stability and charge retention ability, particularly under rest conditions. [ABSTRACT FROM AUTHOR]

Defect‐engineering is a viable strategy to improve the activity of nanocatalysts for the oxygen evolution reaction (OER), whose slow kinetics still strongly limits the broad market penetration of electrochemical water splitting as a sustainable technology for large‐scale hydrogen production. High‐entropy spinel oxides (HESOs) are in focus due to their great potential as low‐cost OER electrocatalysts. In this work, electrospun HESO nanofibers (NFs), based on (Cr,Mn,Fe,Co,Ni), (Cr,Mn,Fe,Co,Zn) and (Cr,Mn,Fe,Ni,Zn) combinations, with granular architecture and oxygen‐deficient surface are produced by calcination at low temperature (600 or 500 °C), characterized by a combination of benchtop analytical techniques and evaluated as electrocatalysts for OER in alkaline medium. The variation of HESO composition and calcination temperature produces complex and interdependent changes in the morphology of the fibers, crystallinity and inversion degree of the spinel oxide, concentration of the oxygen‐vacancies, cation distribution in the lattice, which mirror on different electrochemical properties of the fibers. The best electrocatalytic performance (overpotential and Tafel slope at 10 mA cm−2: 360 mV and 41 mV dec−1, respectively) pertains to (Cr1/5Mn1/5Fe1/5Co1/5Ni1/5)3O4 NFs calcined at 500 °C and results from the lower outer 3d‐electron number, eg filling closer to its optimal value and higher occupation of 16d sites by the most redox‐active species. [ABSTRACT FROM AUTHOR]

NiO-based films and nanostructured materials have received increasing attention for a variety of technological applications. Among the possible strategies for their fabrication, atomic layer deposition (ALD) and chemical vapor deposition (CVD), featuring manifold advantages of technological interest, represent appealing molecule-to-material routes for which a rational precursor design is a critical step. In this context, the present study is focused on the coordination sphere engineering of three heteroleptic Ni(II) β-diketonate–diamine adducts of general formula [NiL2TMEDA] [L = 1,1,1-trifluoro-2,4-pentanedionate (tfa), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate (fod) or 2,2,6,6-tetramethyl-3,5-heptanedionate (thd), and TMEDA = N,N,N′,N′-tetramethylethylenediamine]. Controlled variations in the diketonate structure are pursued to investigate the influence of steric hindrance and fluorination degree on the chemico-physical characteristics of the compounds. A multi-technique investigation supported by density functional calculations highlights that all complexes are air-insensitive and monomeric and that their thermal properties and fragmentation patterns are directly dependent on functional groups in the diketonate ligands. Preliminary thermal CVD experiments demonstrate the precursors' suitability for the obtainment of NiO films endowed with flat and homogeneous surfaces, paving the way to future implementation for CVD end-uses. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the author discusses various articles within the issue on topics including article from researchers at Toyota Motor Co. on advances in the fuel cell stack, history of electrochemical production technology and reversible oxygen electrodes.

The in situ identification of fuel-cell material parameters is crucial both for guiding the research for advanced functionalized materials and for fitting multiphysics models, which can be used in fuel cell performance evaluation and optimization. However, this identification still remains challenging when dealing with direct measurements. This paper presents a method for achieving this aim by stochastic optimization. Such techniques have been applied to the analysis of fuel cells for ten years, but typically to specific problems and by means of semi-empirical models, with an increased number of articles published in the last years. We present an original formulation that makes use of an accurate zero-dimensional multi-physical model of a polymer electrolyte membrane fuel cell and of two cooperating stochastic algorithms, particle swarm optimization and differential evolution, to extract multiple material parameters (exchange current density, mass transfer coefficient, diffusivity, conductivity, activation barriers …) from the experimental data of polarization curves (i.e. in situ measurements) under some controlled temperature, gas back pressure and humidification. The method is suitable for application in other fields where fitting of multiphysics nonlinear models is involved. [ABSTRACT FROM AUTHOR]

• Green synthesis of MnO x NPs (20 nm) using olive leaf extract as a surfactant. • Mn 2 O 3 exhibits stability within the temperature range [600 °C-900 °C]. • Mn 3 O 4 appears between 300 °C and 600 °C, and reappears at 1000 °C. • MnO x structures show mesoporous characteristics with high surface area. This paper presents the green synthesis of manganese oxide nanoparticles using olive leaf extract (OLE). The extract functions as both a reducing agent, responsible for converting manganese ions into nanoparticles, and a capping agent, aiding in stabilizing the formed nanoparticles. Our focus lies on investigating the thermal stability, phase transformation, and decomposition temperatures of different manganese oxide phases in powder form as a function of the calcination temperature. Since phase transformation depends on temperatures change at the nanoscale both thermogravimetric and differential scanning calorimetry (TGA, DSC) are used to determine the new phase transformation temperatures of the synthesized nanoparticles. Moreover, the phase structure and the exact stoichiometry are studied using ex-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning/transmission electron microscopy (SEM/TEM). XRD and XPS analyses reveal the formation of amorphous MnO x at room temperature (prior to calcination), transitioning to crystalline phases (Mn 2 O 3 and Mn 3 O 4) post-calcination. High-resolution TEM and SEM depict the formation of nanoparticles around 15 nm in size, exhibiting different shapes. BET technique calculations give a very high specific surface area, rending these nanoparticles excellent candidates for several applications. [ABSTRACT FROM AUTHOR]

New inorganic‐organic hybrid anion exchange membranes are produced after incorporation of tantalum oxide into trimethylammonium‐functionalized polyethylene pyrrole‐co‐polyethylene ketone (functionalized polyketone, FPK), obtained by the chemical modification of a polyketone polymer. The influence of tantalum oxide fillers on the properties of the synthesized membranes is investigated. The interaction between inorganic fillers and the polymer chains is studied using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR‐FTIR). The thermal analysis of the FPK membranes reveals they are thermally stable at up to 250°C. However, the incorporation of the inorganic fillers reduces the thermal stability. Modulated Differential Scanning Calorimetry (MDSC) results indicate that the inclusion of inorganic fillers leads to an increase in crystallinity. This study reports that the properties of the bulk polymer can be tuned by controlling the degree of functionalization and content of inorganic fillers, as confirmed by Near Ambient Pressure X‐Ray Photoelectron Spectroscopy (NAP‐XPS) studies. Finally, Broadband Electrical Spectroscopy (BES) studies demonstrate that the hybrid membranes are characterized by several polarization phenomena contributing to the overall ion conductivity of the material, which at RT is of 1.46 and 1.61 mS cm−1 for the FPK cast membrane and the hybrid membrane with 5.0 wt.% of Ta2O5 filler, respectively. [ABSTRACT FROM AUTHOR]

The sodium-ion battery (Na-ion battery, NIB) is considered the most promising post-lithium energy storage technology, taking advantage of using the same manufacturing technology as Li-ion batteries (LIBs), while enabling the use of more abundant and economic, thus more sustainable, raw materials. Due to the inability of Na+ ions to be intercalated within the graphene-layered structure of graphite-based electrodes (the state of art anode material in LIBs), highly disordered and microporous carbons, known as hard carbons, are considered the anode material of choice for NIB technology. Biomass-derived biochar (BC) is one of the most relevant classes of hard carbons, exhibiting a good combination of sustainable fabrication, structural-morphological features and electrochemical performances. In this review, the main achievements on BC are rigorously reported from the production to the application into NIBs, with particular emphasis on the strategies to improve the electrochemical behaviour of BC by activating it and tailoring its chemical and structural properties. These strategies include selecting specific feedstocks, modulation of the pyrolysis temperature, pre- and post-production treatments, and materials engineering. The possible role of BC in sustainable NIBs development is also briefly discussed, together with some insights of its use in other post-Li energy storage systems and some concluding remarks and future direction of the research. • Na-ion battery is amongst the most promising post-Li energy storage technologies. • Na-ion battery requires the use of hard carbon as anode materials. • Biochar is one of the most relevant classes of hard carbons. • Biochar structure and chemical features can be tuned during or after production. • Main results on biochar in batteries are reported, from production to application. [ABSTRACT FROM AUTHOR]

A polyketone-b-poly[N-(4 methyl-methylpyridium)-ethylenepyrrole+][X−], with X− = I− or OH−, is investigated as an example of anion-exchange membrane with potential applications in fuel cells. The polyketone starting material PK and the functionalized polyketones Pyr-FPKmI and Pyr-FPKmOH are investigated via Broadband Electrical Spectroscopy (BES) to understand the conductivity mechanism. BES signals are collected in the frequency range of 10−2 – 107 Hz and from −100° to 120 °C. BES measurements reveal the presence of up to three interdomain polarizations phenomena, one electrode polarization event and two β dielectric relaxation modes for both wet Pyr-FPKmI and Pyr-FPKmOH. Ion conductivity for Pyr-FPKmI and Pyr-FPKmOH is found to be 0.0086 and 0.0105 S cm−1 at 80 °C, respectively. The overall conductivity mechanism is attributed to the superposition of two conduction pathways, via delocalization bodies and via interdomain percolation pathways, which are associated with two different physical phenomena. [ABSTRACT FROM AUTHOR]

A series of samples are collected from the catholyte solution of a vanadium redox flow battery (VRFB) at different values of state of charge (SoC)/state of discharge (SoD). The samples are analyzed by means of Raman spectroscopy to identify: (i) the species present into the catholyte; and (ii) how the composition of the catholyte is modulated along the charge and discharge processes of the VRFB. Raman results reveal that the most abundant species in the catholye are VO2+ and VO 2 +; they are coordinated by HSO 4 − and SO 4 2− ligands. During the charge process of the VRFB the equilibrium between the vanadium species is shifted towards the formation of an ensemble of V(V) complexes. Instead, during discharge a family of V(IV) species is obtained. The formation of concatenated HV 2 O 5 − and H 3 V 2 O 7 − species in the catholyte is revealed, which indicates that side electrochemical reactions occur during the charge and discharge processes of a VRFB. The presence of these side reactions plays a crucial role in the modulation of the Coulombic efficiency of the VRFB. This work highlights the complexity of the chemical situation at a VRFB cathode, and the great importance to understand/control such chemical situation to improve the performance of VRFBs in the scenario of electrochemical energy storage field. • A vanadium redox flow battery system is tested under operating conditions. • The catholyte solution is investigated by Raman spectroscopy. • Samples are collected at different values of state of charge/state of discharge. • Concatenated complexes with more than one vanadium atom are detected. • VO2+ ↔ VO 2 + is not the only redox reaction taking place in the system. [ABSTRACT FROM AUTHOR]

The development of innovative proton-conducting membranes exhibiting an improved [H+/VO2+] ion selectivity in comparison with baseline perfluorinated ionomers (e.g. , Nafion) is critical to prompt the large-scale implementation of vanadium redox flow batteries (VRFBs) characterized by a performance and cyclability compatible with the applications. This paper pursues this objective by reporting the preparation and characterization of a new family of hybrid inorganic-organic membranes, that are labeled "[SPEEK/(WO 3) x ]" , consisting of a sulfonated poly (ether ether ketone) (SPEEK) matrix hosting between 0 and 23.6 wt% of WO 3 nanoparticles (NPs). The physicochemical characterization of the [SPEEK/(WO 3) x ] membranes elucidates the impact of the introduction of WO 3 NPs on the thermal, structural and transport properties of the SPEEK host. It is found that the [SPEEK/(WO 3) 0.20 ] membrane presents the highest [H+/VO2+] ion selectivity (2.1 × 104 S min cm−3), that is more than three times higher than that of recast Nafion (6.5 × 103 S min cm−3). [SPEEK/(WO 3) 0.20 ] is then mounted in a single cell VRFB, that is tested extensively under realistic operating conditions and demonstrates a coulombic efficiency and cyclabilty that are improved with respect to the corresponding figures of a VRFB incorporating a Nafion 212 membrane to provide the basis for a comparison. This outcome is in compliance with the result of the "ex-situ" investigations, and allows for the proposal of a structural model correlating the physicochemical properties of the [SPEEK/(WO 3) x ] membranes with the transport properties and the proton conductivity. • Hybrid [SPEEK/(WO 3) x ] membranes are prepared and investigated for application in VRFBs. • The transport properties of the [SPEEK/(WO 3) x ] membranes are strongly influenced by x. • At 30 °C the [H+/VO2+] ion selectivity of [SPEEK/(WO 3) 0.20 ] is 3.2 times higher than that of Nafion 212. • The VRFB mounting [SPEEK/(WO 3) 0.20 ] shows a lower capacity fade than that mounting Nafion 212. [ABSTRACT FROM AUTHOR]

Abstract This work reports two quasi-solid composite electrolytes based on LiFT (Lithiated Fluorinated Titania) nanopowder and either 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4) or 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) ionic liquid (IL). In details, LiFT nanopowder is doped with ca. 30 wt% of IL, giving rise to materials with formula LiFT/(EMImBF 4) 0.183 and LiFT/(EMImTFSI) 0.087. The resulting composite electrolytes appear as powder-like solids as the IL is completely absorbed by LiFT. The correlation between structure, thermal properties and long-range charge migration processes of the here proposed electrolytes is investigated by several characterization techniques, as follows: i) differential scanning calorimetry (DSC) and high-resolution thermogravimetry (HR-TGA); ii) Fourier-transform infrared spectroscopy in both the medium and the far infrared (FT-MIR and FT-FIR); and iii) broadband electrical spectroscopy (BES). The conductivity of the here proposed composite electrolytes is promising. Indeed, at 30 and 100 °C it corresponds respectively to 1.75 × 10−3 S cm−1 and 1.05 × 10−2 S cm−1 for LiFT/(EMImBF 4) 0.183 , and 1.36 × 10−2 S cm−1 and 4.42 × 10−2 S cm−1 for LiFT/(EMImTFSI) 0.087. Finally, LiFT/(EMImTFSI) 0.087 is used to fabricate a coin cell prototype, that is tested by galvanostatic cycling for performance and durability. Highlights • Two composite electrolytes are obtained, appearing as powder-like solids. • Li+BF 4 − and [Li(TFSI) 2 ]- are formed owing to the dissociation of Li+ from LiFT component. • At 30 °C a conductivity of 1.36 × 10−2 S cm−1 is achieved by LiFT/(EMImTFSI) 0.087. • Li+ are exchanged between LiFT nanoparticles and among adjacent ionic aggregates. • Battery cycling is achieved using a quasi-solid composite electrolyte. [ABSTRACT FROM AUTHOR]

Abstract The potential for metallic lithium batteries that exhibit high specific capacities has stimulated a large interest within the energy research field. For safety reasons, the use of metallic lithium anodes requires electrochemically stable electrolytes. However, to date there has been limited success in this area. This work introduces a solid, lithium single-ion conductor thus providing new perspectives in the field of solid-state lithium-batteries. This new-concept material (LiFT), obtained by a direct reaction of nanometric fluorinated titanium oxide (FT) with molten metallic lithium, consists of nanoparticles (NPs) with anionic surface groups that are neutralized with lithium cations. The material displays fast lithium ion transport via an efficient migration mechanism occurring at the interfaces between different nanoparticles. The electrolyte comprises 1.34 mol kg−1 of Li and a conductivity of 2.8·10−4 S cm-1 at 25 °C is demonstrated. This level of performance, in conjunction with a native electrochemical stability towards lithium, extremely low cost starting materials (TiO 2) and a facile one-pot synthesis, renders this electrolyte very attractive for applications in future full solid-state lithium batteries. Graphical abstract Image 1 Highlights • An inorganic solid-state electrolyte for lithium batteries is prepared through an innovative one-step synthesis. • The electrolyte shows a high conductivity due to the hopping of Li cations at the interfaces between anatase -based NPs. • Good prototype performance and full solid-state cyclic voltammetry are demonstrated. [ABSTRACT FROM AUTHOR]

Membranes of polyamine (PA-SiNH 2 ) m , containing silica reacted with 3-aminopropyltriethoxysilane (APTES) in hydrolytic conditions were prepared via solution casting, followed by methylation and ion exchange process. The influence of amino-functionalized silica (Si-NH 2 ) on the properties of the obtained membrane was investigated. Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance spectroscopy (NMR) were used to investigate the chemical features of the silica and its interaction with the polyamine polymer. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the modified membrane confirmed it is stable up to 300 °C. The thermal stability is the result of the interaction of modified silica particles and polyamine polymer. It was demonstrated that the performance of the (PA-SiNH 2 ) m anion exchange membrane is greatly improved by incorporation of silica nanoparticles as compared with the anion exchange membrane (PK-PDAPm), which doesn't contain silica. Therefore, the (PA-SiNH 2 ) m is a suitable candidate for electrochemical applications. [ABSTRACT FROM AUTHOR]

This work reports the synthesis, the physicochemical characterization and the electrochemical studies of new electrocatalysts (ECs) for the oxygen reduction reaction (ORR) that: (i) exhibit a hierarchical architecture; and (ii) do not comprise platinum. The active sites of the ECs consist of Fe and Sn species stabilized in “ coordination nests ” of a carbon nitride (CN) matrix. The latter exhibits a rough, microporous morphology and acts as a “ shell ” covering a graphene “ core ”. This paper: (i) discusses the role played by Fe as the “ active metal ” in this family of ECs; and (ii) examines in detail how the physicochemical properties and, correspondingly, the electrochemical performance are affected by a suitable activation procedure A meant to boost the ORR kinetics. The results lead to an improved fundamental understanding on the features of the active sites, including the impact of both A and the pH of the environment in their performance and ORR mechanism. These insights clarify the most desirable features to be included in high-performing ECs belonging to this family, paving the way to the synthesis of next-generation, efficient ECs for the ORR that do not comprise platinum. [ABSTRACT FROM AUTHOR]

The quest for the development of high performing secondary batteries is prompting the research activities in this field towards the exploitation of new cell concepts. In this concern, next-generation secondary batteries based on multivalent metals such as magnesium and tin are an important promise. In this report, a new family of multivalent metal-based ionic liquid (IL) electrolytes is developed. The proposed ILs are obtained by reacting 1-butyl-1-methylpyrrolidinium chloride (Pyr 14 Cl), dimethyl-tin dichloride and the highly electroactive δ-MgCl 2 material. Thermal and vibrational spectroscopy studies reveal that the proposed electrolytes consist of domains of complex catenated 3D magnesium-organochlorostannate coordination networks neutralized by aggregates of Pyr 14 + stacks. The anionic domains are composed by a network of catenated [Me 2x Sn x Cl 2x + y ]y− repeat units bonded by MgCl x bridges. Cyclic voltammetry studies reveal that the metal deposition and stripping processes occur with a low overpotential in the order of few tens of mV. Finally, broadband electrical spectroscopy studies show that these new IL electrolytes: (i) are characterized by a room temperature ionic conductivity in the order of 10−3 S cm−1; and (ii) exhibit host matrix relaxations which are very effective in facilitating the long-range charge migration processes responsible for the overall conductivity of materials. [Display omitted] • Ionic liquid electrolytes for secondary battery applications are proposed. • Metal is depositing with low overpotential and good current density. • Broadband electrical spectroscopy clarifies the conductivity mechanism. • Complex catenated Mg-based anionic 3D networks are formed. [ABSTRACT FROM AUTHOR]

Abstract: The numerous potential benefits of incorporating anion‐exchange membranes (AEMs), in place of proton‐exchange membranes (PEMs), in energy storage and conversion technologies renders their development of fundamental importance for the continued evolution of alternative energy systems. However, the widespread implementation of AEMs is currently plagued by a range of problems including lower conductivity (with respect to PEMs), poor stability, and high cost. This study reports the conversion of polyketone, one of the world's most mass produced and cheap polymers, to a new highly tuneable polymer architecture, functionalized polyketone (FPK), that demonstrates a range of excellent properties rendering it a significant prospect for AEM materials. The thermal, processing, and ion‐conducting properties of FPK are governed by the amount and nature of the newly formed N‐substituted pyrrole pendant side groups. At 80 °C, the quarternized pyridyl FPK derivative (4MPyrFPK) yields ion‐conductivities of 8.6 and 10.5 mS cm−1 in the iodide and hydroxide forms. In addition, the hydroxide form of 4MPyr‐FPK demonstrates remarkable stability toward the typically problematic alkaline conditions. No chemical decomposition is observed to the membrane after imbibing it in KOH solution for 72 h, and furthermore, the ion‐conductivity is demonstrated to remain constant for at least 30 d at 80 °C. [ABSTRACT FROM AUTHOR]

The electrical response of zirconia composite polybenzimidazole membranes [PBI4N(ZrO 2 ) x ](H 3 PO 4 ) y is studied by Broadband Electrical Spectroscopy (BES), and correlated with our previous Dynamic Mechanical Analysis (DMA) and Modulated Differential Scanning Calorimetry (MDSC) measurements. The presence of nanofiller in the PBI4N polymer matrix is shown to plasticize the membrane, with a maximum effect observed at a nanofiller loading level of x ≈ 0.13. The disrupting effect of the nanofiller on the interchain dipole interactions modulates the overall electrical response of the materials. Following acid doping, a marked increase in conductivity is observed as new chemistry is installed at the interfaces between polymer and nanofiller that facilitates dipolar fluctuations and segmental motions of the polymer chains. In these composite membranes, two mechanisms of conductivity are postulated based on BES analysis; i) proton hopping between binding sites, and ii) proton hopping at the interfaces between H n PBI4N n+ /H n PBI4N n+ and H n PBI4N n+ /H m ZrO 2 m+ . The results here presented demonstrate the effect of zirconia nanofiller and subsequent acid doping on the conductivity properties of composite PBI4N membranes. Of note, at 100 °C for [PBI4N(ZrO 2 ) 0.132 ](H 3 PO 4 ) 11 , conductivity as high as 0.035 S/cm is achieved. [ABSTRACT FROM AUTHOR]

In this study, a new family of poly(vinyl alcohol)-based solid membrane electrolytes is proposed. The single ion conducting polyelectrolytes are obtained by direct lithiation of partially hydrolyzed poly(vinyl alcohol), forming a lithium-poly(vinyl alkoxide) macromolecular salt. Furthermore, in order to improve the ionic conductivity, the obtained polymer is plasticized with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) ionic liquid. Thermogravimetric analysis demonstrates a thermal stability higher than 215 °C. Differential Scanning Calorimetry studies show a polymer associated glass transition event and a melting transition related to the ionic liquid domains at ca. +80 and −40 °C respectively. Fourier-transform infrared spectroscopy proves that: a) lithiation of the membrane results in an increase to the amorphic character of the polymer backbone; and b) after ionic liquid addition to the lithiated membrane, the effective coordination of lithium cations by the TFSI - anions of the ionic liquid augments the ionic conductivity of the proposed materials. Broadband electrical spectroscopy (BES) investigations reveal that this system is characterized by several polarization phenomena and dielectric relaxation events. Analysis of the BES results, using suitable models, allows for the conductivity mechanism in the proposed polymer electrolytes to be hypothesized. Finally, the ionic conductivity values of 1.29 · 10 −5  S cm −1 and 1.92 · 10 −3  S cm −1 at 30 and 80 °C render these materials very promising for application in electrochemical devices. [ABSTRACT FROM AUTHOR]

Nafion‑tungsten oxide hybrid membranes, [Nafion/(WO 3 ) x ], with varying loading levels of WO 3 nanofiller (x = 0, 0.024, 0.329) are prepared and investigated as candidates for application as solid electrolytes in vanadium redox flow batteries (VRFBs). The thermal properties of [Nafion/(WO 3 ) x ] hybrid membranes are probed both by high-resolution thermogravimetric analysis (HR-TGA) and by modulated differential scanning calorimetry (MDSC). Vibrational spectroscopy studies are carried out by: (i) Attenuated Total Reflectance - Fourier Transform Infrared spectroscopy (ATR-FTIR); and (ii) Raman spectroscopy, to elucidate the secondary structure of [Nafion/(WO 3 ) x ] and study the interactions taking place between the nanofiller and the Nafion matrix. The electrical response of [Nafion/(WO 3 ) x ] is determined by Broadband Electrical Spectroscopy (BES) and the permeability towards VO 2+ is measured by UV-VIS spectrometry. It is demonstrated that the [Nafion/(WO 3 ) x ] hybrid membranes exhibit a high ion selectivity (up to 10.6∙10 3  S∙min∙cm −3 for [Nafion/(WO 3 ) 0.329 ]) that is much improved in comparison with that characterizing recast Nafion (6.5∙10 3  S∙min∙cm −3 ). A structural model and a conductivity mechanism for the [Nafion/(WO 3 ) x ] hybrid membranes are proposed, in order to rationalize the experimental results and correlate the electrical response with the transport properties. [ABSTRACT FROM AUTHOR]

We report on the development of two new Pt-free electrocatalysts (ECs) for the oxygen reduction reaction (ORR) process based on graphene nanoplatelets (GNPs). We designed the ECs with a core-shell morphology, where a GNP core support is covered by a carbon nitride (CN) shell. The proposed ECs present ORR active sites that are not associated with nanoparticles of metal/alloy/oxide but are instead based on Fe and Sn subnanometric clusters bound in coordination nests formed by carbon and nitrogen ligands of the CN shell. The performance and reaction mechanism of the ECs in the ORR are evaluated in an alkaline medium by cyclic voltammetry with the thin-film rotating ring-disk approach and confirmed by measurements on gas-diffusion electrodes. The proposed GNP-supported ECs present an ORR overpotential of only ca. 70 mV higher with respect to a conventional Pt/C reference EC including a XC-72R carbon black support. These results make the reported ECs very promising for application in anion-exchange membrane fuel cells. Moreover, our methodology provides an example of a general synthesis protocol for the development of new Pt-free ECs for the ORR having ample room for further performance improvement beyond the state of the art. [ABSTRACT FROM AUTHOR]

Molecular engineering of manganese(II) diamine diketonate precursors is a key issue for their use in the vapor deposition of manganese oxide materials. Herein, two closely related β-diketonate diamine MnII adducts with different fluorine contents in the diketonate ligands are examined. The target compounds were synthesized by a simple procedure and, for the first time, thoroughly characterized by a joint experimental-theoretical approach, to understand the influence of the ligand on their structures, electronic properties, thermal behavior, and reactivity. The target compounds are monomeric and exhibit a pseudo-octahedral coordination of the MnII centers, with differences in their structure and fragmentation processes related to the ligand nature. Both complexes can be readily vaporized without premature side decompositions, a favorable feature for their use as precursors for chemical vapor deposition (CVD) or atomic layer deposition applications. Preliminary CVD experiments at moderate growth temperatures enabled the fabrication of high-purity, single-phase Mn3O4 nanosystems with tailored morphology, which hold great promise for various technological applications. [ABSTRACT FROM AUTHOR]

• Silicotungstic acid (H 4 SiW 12 O 40) exhibits fast and reversible redox processes. • Charge propagation dynamics can be studied with microelectrode-based cells. • H 4 SiW 12 O 40 crystals, concentrated solutions and colloidal suspensions can be explored. • Electron hopping between mixed-valent tungsten sites coexists with physical diffusion. • Applicability of H 4 SiW 12 O 40 redox electrolytes can be probed with microelectrodes. Concentrated solutions of Keggin-type silicotungstic acid, as well as the system's single crystals (H 4 SiW 12 O 40 *31H 2 O) and their colloidal suspensions have been tested using the microelectrode methodology to determine mass-transport, electron self-exchange and apparent (effective) diffusion-type coefficients for charge propagation and homogeneous (electron self-exchange) rates of electron transfers. Silicotungstic acid facilitates proton conductivity, and undergoes fast, reversible, multi-electron transfers leading to the formation of highly conducting, mixed-valence (tungsten(VI,V) heteropoly blue) compounds. To develop useful electroanalytical diagnostic criteria, electroanalytical approaches utilizing microdisk electrodes have been adapted to characterize redox transitions of the system and to determine kinetic parameters. Combination of microelectrode-based experiments performed in two distinct diffusional regimes: radial (long-term experiment; e.g., slow scan rate voltammetry or long-pulse chronoamperometry) and linear (short-term experiment; e.g., fast scan rate voltammetry or short-pulse chronocoulometry) permits absolute determination of such parameters as effective concentration of redox centers (C 0) and apparent transport (diffusion) coefficient (D app). The knowledge of these parameters, in particular of [ D app 1/2 C 0 ] seems to be of importance to the evaluation of utility of redox electrolytes for charge storage. For the colloidal suspension of silicotungstic acid (H 4 SiW 12 O 40) crystals in the saturated solution, the following values have been obtained: D app = 1.8*10-6 cm2 s−1 and C 0 = 1.1 mol dm−3, as well as the [ D app 1/2 C 0 ] diagnostic parameter has reached the value as high as 6*10-3 mol/dm−3 cm s−1/2, provided that four electrons are involved in the H 4 SiW 12 O 40 redox transitions. In this respect, the fact that crystals (dispersed solids) are characterized by high electron self-exchange rate (k ex = 1.1*108 dm3 mol−1 s−1) and low activation energy (E A = 18.7 kJ mol−1) facilitating electron transfers between immobilized WVI and WV redox sites is also advantageous. [ABSTRACT FROM AUTHOR]

Chemically-reduced graphene-oxide-supported gold nanoparticles with a diameter, of 40–60 nm are considered here as catalytic materials for the reduction of oxygen in alkaline medium in comparison to analogous systems based on conventional Vulcan carbon carriers. Gold nanoparticles are prepared by the chemical reduction method, in which the NaBH 4 -prereduced Keggin-type phosphomolybdate heteropolyblue acts as the reducing agent for the precursor (HAuCl 4 ). Polyoxometallate (PMo 12 O 40 3− ) capping ligands stabilize gold nanoparticle deposits, facilitate their dispersion and attachment to carbon supports. Indeed, it is apparent from the independent diagnostic voltammetric experiments (in 0.5 mol dm −3  H 2 SO 4 ) that heteropolymolybdates form readily stable adsorbates on nanostructures of both gold and carbon (reduced graphene oxide and Vulcan). It is reasonable to expect that the polyoxometallate-assisted nucleation of gold has occurred in the proximity of oxygenated defects existing on carbon substrates. Under conditions of electrochemical diagnostic experiments (performed in 0.1 mol dm −3 KOH): ( i ) the phosphomolybdate adsorbates are removed from the interface as they undergo dissolution in alkaline medium; and ( ii ) the Au nanoparticles (Au loading, 30 μg cm −2 ) remain well-dispersed on the carbon as evident from transmission electron microscopy. High electrocatalytic activity of the reduced-graphene oxide-supported Au nanoparticles toward reduction of oxygen in alkaline medium is demonstrated using cyclic and rotating ring-disk voltammetric experiments. The latter system could also act as the active support for Pt nanoparticles during the reduction of oxygen. Among important issues are possible activating interactions between gold and the support, as well as presence of structural defects existing on poorly organized graphitic structure of reduced graphene oxide (as evident from Raman spectroscopy). [ABSTRACT FROM AUTHOR]

Relaxation and polarization phenomena of phosphoric acid-doped [PBI4N(HfO 2 ) x ](H 3 PO 4 ) y nanocomposite membranes for high-temperature proton-exchange membrane fuel cells are studied using Dynamic Mechanical Analysis (DMA) and Broadband Electrical Spectroscopy (BES). The membranes are obtained by casting combinations of a polybenzimidazole polymer (PBI4N) with increasing amounts of hafnium oxide nanofiller, resulting in [PBI4N(HfO 2 ) x ] hybrid systems with 0 ≤ x ≤ 0.32. Phosphoric acid at varying content levels (0 ÷ 18 wt%) is used as a doping agent, giving rise to [PBI4N(HfO 2 ) x ](H 3 PO 4 ) y membranes. DMA and BES studies lead us to determine that the electric response of the membranes is modulated by polarization phenomena and by α and β dielectric relaxation events of the polymer matrix. Additionally, the experimental results suggest that in [PBI4N(HfO 2 ) x ](H 3 PO 4 ) y membranes the conductivity occurs owing to three conductivity pathways: two mechanisms involving inter-domain proton migration phenomena by “hopping” events; and one mechanism in which proton exchange occurs between delocalization bodies. These results highlight the significant effect of the hafnium oxide nanofiller content on the conductivity of [PBI4N(HfO 2 ) x ](H 3 PO 4 ) y where, at x ≥ 0.04, demonstrates conductivity higher (9.0 × 10 −2 S/cm) than that of pristine H 3 PO 4 -doped PBI4N (4.8 × 10 −2 S/cm) at T ≥ 155 °C. [ABSTRACT FROM AUTHOR]

An anion exchange membrane (AEM) was made with a modified polyketone (PK). AEMs of polyamines were prepared in a three-step procedure: (I) PK synthesis using ethylene and carbon monoxide, supported by a Pd catalyst, followed by the introduction of 1,2-diaminopropane to yield the polymeric amines; (II) solvent casting of the modified PK with a low degree of amination; (III) iodomethylation to form the AEM (PK-PDAPm(I)), followed by ion exchange with KOH (PK-PDAPm(OH)). The structure of the modified polyketone was characterized using FT-IR, and UV–vis spectroscopy, demonstrating the successful introduction of amine in the PK. The conductivity of the AEM was studied using broadband electric spectroscopy (BES) in the temperature range from −100 to 120 °C: the highest value of 9 × 10 −4 S·cm −1 was reached at 120 °C for the ionic conductivity of PK-PDAPm(I), followed by PK-PDAPm(OH) with values of the same order of magnitude (10 −4 S·cm −1 ). Thermogravimetry showed that the material is thermally stable up to 200 °C. [ABSTRACT FROM AUTHOR]

This report describes the preparation, characterization, and coin cell prototype testing of new Li[Fe 1/3 Ni 1/3 Co 1/3 ]PO 4 high voltage olivine cathodes for lithium secondary batteries (LFNCPs) obtained by treating the precursors with Cu and Cu+C sources. The morphology, structure, interactions, and electrochemical properties of the obtained materials are extensively studied in order to elucidate the interplay in LFNCPs between graphite (C) and copper(II) carbonate (Cu) addition to the precursors and structural flexibility, relaxations, and electrochemical performance of obtained materials. In particular, the investigated LFNCPs cathodes are obtained by treating the reaction precursors with graphite nanoparticles and/or copper(II) carbonate. It is found that copper does not behave like a vicariant metal ion within the olivine structure of the cathodes, instead it forms segregated CuO nanoparticles which improve the charge-transfer kinetics during the charge/discharge processes of the cathode material. The graphite additive in precursors is found to decompose during the synthesis, resulting in an improved elasticity of the 3D structure of the olivine backbone. This increased structural flexibility facilitates the percolation of lithium ions along the 1D channels of the materials during the charge/discharge processes. Coin cell prototypes assembled with the proposed cathode materials show good specific capacities (>100 mAh g −1 ), good specific energies (455 mWh g −1 ), and a high working potential (>4.0 V). [ABSTRACT FROM AUTHOR]

This report presents the interplay between the synthesis parameters, physicochemical properties, and electrochemical performance of core-shell low-Pt electrocatalysts (ECs) for the oxygen reduction reaction (ORR) based on Pt x Ni active sites stabilized on a carbon nitride shell. The impact of the pyrolysis temperature (T f), of the support core (H) composition and of an electrochemical dealloying-activation step on the EC morphology and on the accessibility and stability of the active sites are studied in detail. Three supports are employed based on carbon nanoparticles and/or graphene platelets. The ORR performance of activated ECs measured by cyclic voltammetry with the thin-film rotating ring-disk electrode approach is strongly affected by T f and H. The best performing ECs are tested in single proton exchange membrane fuel cells under operating conditions. The simultaneous presence of graphene and carbon in H improves the dispersion of active sites, resulting in a vastly improved mass activity and durability in comparison with a benchmark state-of-the-art Pt/C EC. [Display omitted] • Hierarchical core-shell Pt–Ni ORR electrocatalysts (ECs) are obtained. • Interplay between synthesis, properties, and performance of ECs is discussed. • Hierarchical Pt–Ni ECs exhibit mass activities surpassing DOE targets. • Hierarchical Pt–Ni ECs are more durable than Pt/C reference ECs. [ABSTRACT FROM AUTHOR]

In this report, the preparation of Fe-carbon nitride (CN)-based electrocatalysts (ECs) with a “core-shell” morphology for the oxygen reduction reaction (ORR) is described. The ECs consist of spherical XC-72R carbon nanoparticles, the “cores” , that are covered by a CN matrix, the “shell” , that embeds Fe species in “coordination nests” . The latter consist of hollow cavities in the CN matrix, whose internal surface is covered by N- and C-ligands able to stabilize alloy nanoparticles or active sites. Two families of CN-based ECs are prepared, which are grouped on the basis of the concentration of N atoms in the CN “shell” . Each group comprises of both a “pristine” and an “activated” EC; the latter is obtained from the “pristine” EC by a suitable series of treatments ( A ) devised to improve the ORR performance. The chemical composition of the CN-based ECs is determined by Inductively-Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and microanalysis. The thermal stability under both inert and oxidizing atmospheres is gauged by High-Resolution Thermogravimetric Analysis (HR-TGA). The structure is probed by powder X-ray diffraction, and the morphology is inspected by Scanning Electron Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HR-TEM). The surface area of the CN-based ECs is determined by nitrogen physisorption techniques, and the surface composition is probed by X-ray Photoelectron Spectroscopy (XPS). The electrochemical performance and reaction mechanism of the CN-based ECs in the ORR is investigated in both acid and alkaline environments by cyclic voltammetry with the Thin-Film Rotating Ring-Disk Electrode setup (CV-TF-RRDE). The influence of the preparation parameters and of the treatments on the physicochemical properties, the ORR performance, and reaction mechanism is studied in detail. In the alkaline environment the FeFe 2 -CN l 900/C A “core-shell” EC shows a remarkable ORR onset potential of 0.908 V vs. RHE which, with respect to the value of 0.946 V vs. RHE of the Pt/C ref., classifies the proposed materials as very promising “Platinum Group Metal-free” ECs for the ORR. [ABSTRACT FROM AUTHOR]

The synthesis, physicochemical properties and conductivity mechanism of a family of ionic liquid-based electrolytes for use in secondary Mg batteries are reported. The electrolytes are obtained by dissolving controlled amounts of δ-MgCl 2 salt into the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4 ) which acts as a solvent. δ-MgCl 2 consists of an inorganic ribbon of Mg atoms covalently bonded together through bridging chlorine atoms. Due to this peculiar structural motif, with respect to the electrolytes based on conventional Mg salts, it is possible to achieve electrolytes of higher Mg concentration. Thus, concatenated anionic complexes bridged via halogen atoms are formed, improving the electrochemical performance of these materials. Electrolytes with a general formula EMImBF 4 /(δ-MgCl 2 ) f with f ranging from 0 to 0.117 are obtained. The composition of the obtained materials is determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). The properties of these systems are investigated by means of Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and vibrational spectroscopy in both medium (MIR) and far infrared (FIR). Finally, Broadband Electrical Spectroscopy (BES) is carried out with the aim to elucidate the electrical response of the electrolytes in terms of their polarization and relaxation phenomena and to propose a conductivity mechanism. At 20 °C the highest conductivity (0.007 S/cm) is observed for the electrolyte with c Mg = 0.00454 mol Mg /kg IL . [ABSTRACT FROM AUTHOR]

Five bimetallic electrocatalysts (ECs) including a carbon nitride (CN) support are synthesised through the pyrolysis of a solid precursor obtained through sol-gel and gel-plastic processes. The resulting ECs are characterised through ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) and XPS (X-ray Photoelectron spectroscopy); their performance and reaction mechanism in the oxygen reduction reaction (ORR) are evaluated with the CV-TF-RRDE method (Cyclic Voltammetry Thin-Film Rotating Ring-Disk Electrode). Special attention is given to XPS results with the aim to carry out a thorough investigation of the surface concentration and the chemical environments of the different elements, as well as providing information on the structure of the metal components of the ECs and their interactions with the carbon nitride support. The correlation of the results obtained from the chemical analyses, XPS and the electrochemical studies allows to improve the fundamental understanding of: (i) the interplay between the preparation parameters and the surface and bulk chemical composition of the CN-supported ECs; and (ii) the factors controlling the ORR kinetics and reaction pathway in bimetallic CN-supported ECs, identifying the roles played by the various metal species. In this regard, the VI-period metal included in each EC has the highest impact on the ORR performance. Indeed, the ORR onset potential rises from ca. 300 to ca. 780 to ca. 900 mV vs. RHE for ECs based on Au, Ir and Pt, respectively. On the other hand, the second metal ( i.e. , Ni, Rh, and also Ir in the case of an EC including both Pt and Ir) plays a secondary role. With respect to the Pt/C ref., the CN-supported EC including Pt and Ni exhibits a higher onset potential (900 and 911 mV vs. RHE, respectively); finally, it is shown that Ir and Rh promote the selectivity of the ORR in the 4-electron mechanism. [ABSTRACT FROM AUTHOR]

This report describes the synthesis and the properties of a series of polymer electrolytes, composed of a hybrid inorganic-organic matrix doped with LiTFSI. The matrix is based on ring-like oligo-siloxane clusters, bearing pendant, partially cross-linked, polyether chains. The dependency of the thermo-mechanic and of the transport properties on several structural parameters, such as polyether chains’ length, cross-linkers’ concentration, and salt concentration is studied. Altogether, the materials show good thermo-mechanical and electrochemical stabilities, with conductivities reaching, at best, 8·10 −5 S cm −1 at 30 °C. In conclusion, the cell performances of one representative sample are shown. The scope of this report is to analyze the correlations between structure and properties in networked and hybrid polymer electrolytes. This could help the design of optimized polymer electrolytes for application in lithium metal batteries. [ABSTRACT FROM AUTHOR]

To cite some of his research activities, it should be mentioned that Roberto Marassi was a pioneer in the field of electrochemical energy storage for more than 40 years, pursuing research in such areas as molten salts or ionic liquids, Na-S batteries, Li-ion batteries, low-temperature fuel cells, and vanadium redox flow batteries, in addition to his interests in electroanalytical chemistry. But Roberto is remembered mainly for his availability to interact with other people, especially the young scientists, as well as for his sincere enthusiasm for the progress in electrochemical science and technology. Roberto Marassi was one of the scientists who, by developing new or by extending existing methods or materials, significantly advanced the understanding of electrochemical energy conversion processes as well as of the fundamentals of electrocatalysis and electroanalysis. [Extracted from the article]

The quest for new electrolyte and cathode materials is a crucial point for beyond-lithium-ion energy storage systems. Following this, an electrolyte for secondary magnesium batteries based on a new iodoaluminate ionic liquid and δ-MgI2 is reported. Promising electrochemical performance in terms of Mg plating-stripping, coulombic efficiency, and conductivity, demonstrates the potential of this iodine-based system for future Mg secondary batteries. [ABSTRACT FROM AUTHOR]

A poly(ethylene glycol) 400 (PEG400) matrix doped with different amounts of a fluorinated Fe 2 O 3 -based nanofiller (LiFI) featuring a Li + -functionalised surface gives rise to nanocomposite polymer electrolytes (nCPEs) that demonstrate single-ion conduction. A family of nCPEs with general formula [PEG400/(LiFI) y ] and y = n Fe /n PEG400 ranging from 0 to 8.15 are prepared; they are characterized by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), High-Resolution Thermogravimetric Analysis (HR-TGA), Differential Scanning Calorimetry (DSC), and Fourier-transform vibrational spectroscopy in both the medium (MIR) and far (FIR) infrared. The Li + transference number, t Li+ ,is determined and Broadband Electrical Spectroscopy (BES) is used to elucidate the electrical response of the materials in terms of polarization and relaxation events. The combination of the information obtained by all the aforementioned techniques enables us to present a possible conduction mechanism for these nCPEs single-ion conducting systems. [ABSTRACT FROM AUTHOR]

New high voltage and high capacity storage systems are needed to sustain the increasing energy demand set by the portable electronics and auto­motive fields. Due to their good electrochemical performance, lithium-transition metal-phosphates (LiMPO4) seem to be very attractive as cathode materials for lithium secondary batteries. Here the synthesis and the characterization of five high voltage cathodes for lithium batteries, based on lithium-iron, lithium-nickel, lithium-cobalt phosphates are described. The effect of differing degrees of cobalt and nickel doping on structure, morphology, and the electrochemical properties of the different materials is thoroughly studied. Transition metal atoms in these materials are found to be vicariant within the olivine crystal structure; however, the lattice parameters and cell volume can be modulated by varying the nickel/cobalt ratio during the synthesis. High performance battery prototypes in terms of voltage (>4.0 V), specific capacity (125 mAh g−1), specific energy (560 mWh g−1), and cyclic life (>150 cycles) are also demonstrated. [ABSTRACT FROM AUTHOR]

New high voltage and high capacity storage systems are needed to sustain the increasing energy demand set by the portable electronics and auto motive fields. Due to their good electrochemical performance, lithium-transition metal-phosphates (LiMPO4) seem to be very attractive as cathode materials for lithium secondary batteries. Here the synthesis and the characterization of five high voltage cathodes for lithium batteries, based on lithium-iron, lithium-nickel, lithium-cobalt phosphates are described. The effect of differing degrees of cobalt and nickel doping on structure, morphology, and the electrochemical properties of the different materials is thoroughly studied. Transition metal atoms in these materials are found to be vicariant within the olivine crystal structure; however, the lattice parameters and cell volume can be modulated by varying the nickel/cobalt ratio during the synthesis. High performance battery prototypes in terms of voltage (>4.0 V), specific capacity (125 mAh g-1), specific energy (560 mWh g-1), and cyclic life (>150 cycles) are also demonstrated. [ABSTRACT FROM AUTHOR]

Research and development of post lithium ion batteries is attracting considerable attention. While there have been significant advances in understanding the challenges of Li-O2(air) and Li-S batteries, the development of gas separation and ion selective membranes will be crucial in their commercialization due to their potential to separate O2from air and impede lithium polysulfide dissolution while permitting rapid diffusion of lithium ions. In addition, research leading to novel and highly conductive and selective polymer electrolytes will be essential in overcoming the deficiencies of liquid based electrolytes in both the air and sulfur based battery systems. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles are recently attracting a lot of interest due to their novel optical, electrical, mechanical, and chemical properties, due to surface and quantum confinement effects. A stable dispersion of ZnO nanoparticles with a uniform particle diameter of 5 nm has been synthesized via chemical precipitation. The surface of the particles has been functionalized with dodecanethiol for enhanced compatibility and dispersion in polymethylmethacrylate (PMMA). Transparent luminescent nanocomposite powders were obtained using solution mixing and solvent casting of ZnO nanoparticles in PMMA. This powder was used to produce injection-molded luminescent nanocomposites plaques. The effect of the ZnO nanoparticles on the polymer structure has been investigated by employing thermomechanical and dielectric spectroscopy analyses. [ABSTRACT FROM AUTHOR]

Polybenzimidazole (PBI) has becomea popular polymer of choicefor the preparation of membranes for potential use in high-temperatureproton exchange membrane polymer fuel cells. Phosphoric acid-dopedcomposite membranes of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole](PBI4N) impregnated with hafnium oxide nanofiller with varying contentlevels (0–18 wt %) have been prepared. The structure–propertyrelationships of both the undoped and acid-doped composite membranesare studied using thermogravimetric analysis, modulated differentialscanning calorimetry, dynamic mechanical analysis, wide-angle X-rayscattering, infrared spectroscopy, and broadband electrical spectroscopy.Results indicate that the presence of nanofiller improves the thermaland mechanical properties of the undoped membranes and facilitatesa greater level of acid uptake. The degree of acid dissociation withinthe acid-doped membranes is found to increase with increasing nanofillercontent. This results in a conductivity, at 215 °C and a nanofillerlevel x≥ 0.04, of 9.0 × 10–2S cm–1for [PBI4N(HfO2)x](H3PO4)y. This renders nanocomposite membranes of this type as goodcandidates for use in high temperature proton exchange membrane fuelcells (HT-PEMFCs). [ABSTRACT FROM AUTHOR]

The development of polymer electrolyteswith high ionic conductivity,high lithium transference number, and high electrochemical stabilityis one of the main aims in the field of lithium battery research.In this work, we describe the synthesis and the characterization ofnew electrolyte systems, composed of three-dimensional hybrid inorganic–organicnetworks doped with LiClO4. The preparation route comprisesonly three steps, namely a sol–gel reaction, salt dissolution,and an epoxide polymerization reaction. The lithium concentration,and thus the lithium transference number, was modulated by addinglithium hydroxide in the sol–gel step. In this way, seven electrolyteswith varying salt concentrations were prepared. The hybrid electrolytesare characterized by good ionic conductivities (up to 8·10–5S/cm at room temperature) and high thermo-mechanicaland electrochemical stabilities. Stability tests versus lithium metalvia galvanostatic polarization showed that this material is superiorwith respect to reference poly(ethylene oxide) based electrolytes. [ABSTRACT FROM AUTHOR]

ABSTRACT The effect of steam on the micro-phase structure and mechanical properties of different block copolymers used in biomedical devices is investigated via FT-IR, tensile tests and dynamic mechanical analysis (DMA). Steam sterilization, commonly performed on medical devices and simulated in this work, affects the copolymers' morphology, due to high temperature and humidity conditions. FT-IR analysis reveals that steam induces a modification in the crystalline conformations of copolymers with a pre-existing hydrogen bonding network, that is, thermoplastic polyurethanes (TPU) and poly(ether-block-amide) (PEBA), while it does not significantly affect the domain conformation in styrenic block copolymers (SEBS), due to weak interaction with water. As a consequence, relevant changes of the mechanical properties, closely related to the microdomain structure, are found for TPU and PEBA after sterilization, while SEBS mechanical behavior remains stable, as demonstrated by tensile tests and DMA results. For this reason, SEBS is suggested as the best choice in terms of durability in biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1337-1346 [ABSTRACT FROM AUTHOR]

B Back Cover b : In article number 2100409 by Voto Di Novo and co-workers, the incorporation of tantalum oxide into trimethylammonium-functionalized polyethylene pyrrole-co-polyethylene ketone is carried out for the preparation of inorganic-organic hybrid anion exchange membranes, which are promising candidates for application in electrochemical energy conversion devices. Inorganic-Organic Hybrid Anion Conducting Membranes Based on Ammonium-Functionalized Polyethylene Pyrrole-Polyethylene Ketone Copolymer. [Extracted from the article]

The development of batteries based on alternatives to lithium is essential to sustaining the increasing global energy demand. Earth abundant, energy dense metal anodes with mixed multivalent ions (e.g. , Mg/Al) are promising next-generation systems. A critical challenge, however, is the development of advanced electrolytes that are compatible with them. To achieve this target, a deeper understanding of their properties and conductivity mechanisms is needed. Herein, in a family of Al/Mg mixed metal ionic liquid-based electrolytes for secondary batteries, the ion-speciation, thermal behavior and long-range charge-migration processes is studied. It is revealed that the chemical compositions and temperature modulate the distribution of AlCl 4 − and Al 2 Cl 7 − species in the anionic nanoaggregates of materials. These modifications are responsible of the mobility of ions, which is studied in detail by means of broadband electrical spectroscopy and pulse-field-gradient NMR. Results yield a clear picture of the role of ion aggregates in the long-range charge-migration processes occurring in these electrolytes. [Display omitted] • Ion speciation and dynamics in IL electrolytes for multivalent metal batteries. • 27Al and 25Mg NMR demonstrates the formation of anionic aggregates. • Broadband electrical spectroscopy elucidates the conductivity mechanism. • 1H PFG-NMR reveals the coupling of dynamics of cation and anion aggregates. [ABSTRACT FROM AUTHOR]