Inherent Behavior of Electrode Materials of Lithium-Ion Batteries.

For independency from the fossil fuels and to save environment, we need to move toward the green energies, which requires better energy storage devices, especially for usage in electric vehicles. Li-ion and beyond-lithium insertion batteries are promising to this aim. However, they suffer from some inherent limitations which must be understood to allow their development and pave the way to find suitable energy storage alternatives. It is found that each positive or negative electrode material (cathode or anode) of the intercalation batteries has its own behavioral (charge-discharge) properties. The modification of preparation parameters (composition, loading density, porosity, particle size, etc.) may improve some aspects of the electrode performance, but cannot change the intrinsic property of the electrode itself. Accordingly, these properties are called as the "inherent behavior characteristics" of the active material. It is concluded that the behavior of a specific electrode substance, even following different preparation routes, depends only on diffusion mechanisms. This work shows that the inherent electrode properties can be visualized by representation of current density vs. capacity.

PVDF-HFP Based, Quasi-Solid Nanocomposite Electrolytes for Lithium Metal Batteries.

Composite polymer electrolytes are systems of choice for future solid-state lithium metal batteries (LMBs). Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is among the most interesting matrices to develop new generation quasi-solid electrolytes (QSEs). Here it is reported on nanocomposites made of PVDF-HFP and pegylated SiO2 nanoparticles. Silica-based hybrid nanofillers are obtained by grafting chains of poly(ethylene glycol) methyl ether (PEG) with different molecular weight on the surface of silica nanoparticles. The functionalized nanofiller improves the mechanical, transport and electrochemical properties of the QSEs, which show good ionic conductivity values and high resistance against dendrite penetration, ensuring boosted long and safe device operation. The most promising result is obtained by dispersing 5 wt% of SiO2 functionalized with short PEG chains (PEG750 , Mw = 750 g mol-1 ) in the PVDF-HFP matrix with an ease solvent-casting procedure. It shows ionic conductivity of 0.1 mS cm-1 at 25 °C, more than 250 h resistance to stripping/plating, and impressive results during cycling tests in LMB with LiFePO4 cathode.

Normalization of charge/discharge time vs. current rate diagrams for rechargeable batteries.

It is vital to comprehend the charge/discharge behaviors of batteries to improve their properties. In this paper, we normalize the electrode materials' behaviors according to the time of the process to allow a rational comparison between different materials and batteries.

Structure-Property Correlations in Aqueous Binary Na+/K+-CH3COO- Highly Concentrated Electrolytes.

Highly concentrated aqueous binary solutions of acetate salts are promising systems for different electrochemical applications, for example, energy storage devices. The very high solubility of CH3COOK allows us to obtain water-in-salt electrolyte concentrations, thus reducing ion activity and extending the cathodic stability of an aqueous electrolyte. At the same time, the presence of Li+ or Na+ makes these solutions compatible with intercalation materials for the development of rechargeable alkaline-ion batteries. Although there is a growing interest in these systems, a fundamental understanding of their physicochemical properties is still lacking. Here, we report and discuss the physicochemical and electrochemical properties of a series of solutions based on 20 mol kg-1 CH3COOK with different concentrations of CH3COONa. The most concentrated solution, 20 mol kg-1 CH3COOK + 7 mol kg-1 CH3COONa, gives the best compromise between transport properties and electrochemical stability, displaying a conductivity of 21.2 mS cm-1 at 25 °C and a stability window of up to 3 V in "ideal" conditions, i.e., using a small surface area and highly electrocatalytic electrode in a flooded cell. Careful Raman spectroscopy analyses help to address the interaction network, the phase evolution with temperature, and the crystallization kinetics.

Unveiling the Role of PEO-Capped TiO2 Nanofiller in Stabilizing the Anode Interface in Lithium Metal Batteries.

Lithium metal batteries (LMBs) will be a breakthrough in automotive applications, but they require the development of next-generation solid-state electrolytes (SSEs) to stabilize the anode interface. Polymer-in-ceramic PEO/TiO2 nanocomposite SSEs show outstanding properties, allowing unprecedented LMBs durability and self-healing capabilities. However, the mechanism underlying the inhibition/delay of dendrite growth is not well understood. In fact, the inorganic phase could act as both a chemical and a mechanical barrier to dendrite propagation. Combining advanced in situ and ex situ experimental techniques, we demonstrate that oligo(ethylene oxide)-capped TiO2, although chemically inert toward lithium metal, imparts SSE with mechanical and dynamical properties particularly favorable for application. The self-healing characteristics are due to the interplay between mechanical robustness and high local polymer mobility which promotes the disruption of the electric continuity of the lithium dendrites (razor effect).

The Electrical Response of Real Dielectrics: Using the Voltage Ramp Method as a Straightforward Diagnostic Tool for Polymeric Composites.

An experimental method exploiting the capacitive response of most materials is here revised. The procedure called the "Voltage Ramp Method" (VRM) is based on applying proper voltage ramp cycles over time and measuring electrical current intensity flowing through the material sample. In the case of an ideal capacitor, a current plateau should be easily measured, and the capacitance value precisely determined. However, most media, e.g., semiconductors and insulating polymers, show dielectric absorption and hence electric leakage effects. Therefore, the VRM method allows simultaneous determination of their equivalent capacitance and resistance. Some case studies are discussed as concerning the application of VRM to both standard and actual media. A figure of merit of the method is the percentage difference between 2.5% and 1.5% with respect to the nominal values of a commercial capacitor and resistor, respectively. The simulation modeling of the material electrical response is compared to the experimental data also on polymer nanocomposites suitable for energy harvesting.

What is Next in Anion-Exchange Membrane Water Electrolyzers? Bottlenecks, Benefits, and Future.

As highlighted by the recent roadmaps from the European Union and the United States, water electrolysis is the most valuable high-intensity technology for producing green hydrogen. Currently, two commercial low-temperature water electrolyzer technologies exist: alkaline water electrolyzer (A-WE) and proton-exchange membrane water electrolyzer (PEM-WE). However, both have major drawbacks. A-WE shows low productivity and efficiency, while PEM-WE uses a significant amount of critical raw materials. Lately, the use of anion-exchange membrane water electrolyzers (AEM-WE) has been proposed to overcome the limitations of the current commercial systems. AEM-WE could become the cornerstone to achieve an intense, safe, and resilient green hydrogen production to fulfill the hydrogen targets to achieve the 2050 decarbonization goals. Here, the status of AEM-WE development is discussed, with a focus on the most critical aspects for research and highlighting the potential routes for overcoming the remaining issues. The Review closes with the future perspective on the AEM-WE research indicating the targets to be achieved.

Cathode Active Material Recycling from Spent Lithium Batteries: A Green (Circular) Approach Based on Deep Eutectic Solvents.

The transition to a circular economy vision must handle the increasing request of metals required to satisfy the battery industry; this can be obtained by recycling and feeding back secondary raw materials recovered through proper waste management. Here, a novel and green proof-of-concept was developed, based on deep eutectic solvents (DESs) to fully and easily recover valuable metals from various cathode active materials, including LiMn2 O4 , LiNi0.5 Mn1.5 O4 , and LiNi0.8 Co0.2 O2 . DES composed of choline chloride and lactic acid could leach Li, Mn, Co, and Ni, achieving efficiency of 100 % under much milder conditions with respect to the previous literature. For the first time, to our best knowledge, a two-step approach was reported in the case of LiNi0.8 Co0.2 O2 for selective recovery of Li, Co, and Ni with high yield and purity. Furthermore, other cathode components, namely aluminum current collector and binder, were found to be not dissolved by the proposed DES, thus making a simple separation from the active material possible. Finally, this strategy was designed to easily regenerate and reuse the leaching solvents for more than one extraction, thus further boosting process sustainability.

Zaltoprofen/4,4'-Bipyridine: A Case Study to Demonstrate the Potential of Differential Scanning Calorimetry (DSC) in the Pharmaceutical Field.

The Zaltoprofen/4,4'-Bipyridine system gives rise to two co-crystals of different compositions both endowed - in water and in buffer solution at pH 4.5 - with considerably higher solubility and dissolution rate than the pure drug. The qualitative and quantitative analysis of the DSC measurements, carried out on samples made up of mixtures prepared according to different methodologies, allows us to elaborate and propose an accurate thermodynamic model that fully takes into account the qualitative aspects of the complex experimental framework and which provides quantitative predictions (reaction enthalpies and compositions of the co-crystals) in excellent agreement with the experimental results. Co-crystal formation and cocrystal compositions were confirmed by X-ray diffraction measurements as well as by FT-IR and NMR spectroscopy measurements. The quantitative processing of DSC measurements rationalizes and deepens the scientific aspects underlying the so-called Tammann's triangle and constitutes a model of general validity. The work shows that DSC has enormous potential, which however can be fully exploited only by paying adequate attention to the experimental aspects and the quantitative processing of the measurements.

Recent Advances in Waste Plastic Transformation into Valuable Platinum-Group Metal-Free Electrocatalysts for Oxygen Reduction Reaction.

Plastic waste causes severe environmental hazards, owing to inadequate disposal and limited recycling. Under the framework of circular economy, there are urgent demands to valorize plastic waste more safely and sustainably. Therefore, much scientific interest has been witnessed recently in plastic waste-derived electrocatalysts for the oxygen reduction reaction (ORR), where the plastic waste acts as a cost-effective and easily available precursor for the carbon backbone. The ORR is not only a key efficiency indicator for fuel cells and metal-air batteries but also a major obstacle for their commercial realization. The applicability of the aforementioned electrochemical devices is limited, owing to sluggish ORR activity and expensive platinum-group metal electrocatalysts. However, waste-derived ORR electrocatalysts are emerging as a potential substitute that could be inexpensively fabricated upon the conversion of plastic waste into active materials containing earth-abundant transition metals. In this Minireview, very recent research developments regarding plastic waste-derived ORR electrocatalysts are critically summarized with a prime focus on the followed synthesis routes, physicochemical properties of the derived electrocatalysts, and their ultimate electrochemical performance. Finally, the prospects for the future development of plastic waste-derived electrocatalysts are discussed.

A physico-chemical investigation of highly concentrated potassium acetate solutions towards applications in electrochemistry.

Water-in-salt solutions, i.e. solutions in which the amount of salt by volume or weight is larger than that of the solvent, are attracting increasing attention in electrochemistry due to their distinct features that often include decomposition potentials much higher than those of lower concentration solutions. Despite the high solubility of potassium acetate (KAC) in water at room temperature (up to 25 moles of salt per kg of solvent), the low cost, and the large availability, the use of highly concentrated KAC solutions is still limited to a few examples in energy storage applications and a systematic study of their physical-chemical properties is lacking. To fill this gap, we have investigated the thermal, rheological, electrical, electrochemical, and spectroscopic features of KAC/water solutions in the compositional range between 1 and 25 mol kg-1. We show the presence of a transition between the "salt-in-solvent" and "solvent-in-salt" regimes in the range of 10-15 mol kg-1. Among the explored compositions, the highest concentrations (20 and 25 mol kg-1) exhibit good room temperature conductivity values (55.6 and 31 mS cm-1, respectively) and a large electrochemical potential window (above 2.5 V).

Insight into the charge/discharge behaviour of intercalation cathode materials: relation between delivered capacity and applied rate and analysis of multi-particle intercalation mechanisms.

Exploration of the relationships and mechanisms underlying the charge/discharge behaviors of intercalation cathode materials for lithium batteries is mandatory to develop more efficient energy storage devices. Thus, herein, by combining theoretical concepts and experimental evidence, we establish/reestablish a relation/model to justify the charge-discharge behavior of many electrode materials for lithium and sodium ion batteries under a wide range of conditions. Our approach resembles a phase-field model and is correlated with the existence of diffusion regions inside the electrode particles. Regarding the determination of the relation between applied current rate and average obtained capacity (C[combining macron]), we propose that 1/C[combining macron] changes linearly versus the square root of the corresponding rate. This relation was established by previously proposed theoretical models and confirmed herein using experimental data from the literature. Accordingly, we propose an intercalation mechanism based on multi-particle (many-particle) systems, which corroborates previous experimental observations and the validity of the model. The proposed concepts can be used for better understanding the behavior of materials, predicting the C[combining macron] value versus current rate, predicting the fraction of (in)active particles, calculating the optimal cathode mass per collector area, and finally obtaining a criterion to evaluate the performance and rate-capability of cathodes, also allowing a functional comparison.

Is It Possible to Obtain Solvent-Free, Li+ -Conducting Solid Electrolytes Based on Pure PVdF? Comment on "Self-Suppression of Lithium Dendrite in All-Solid-State Lithium Metal Batteries with Poly(vinylidene difluoride)-Based Solid Electrolytes".

Is It Possible to Obtain Solvent-Free, Li+ -Conducting Solid Electrolytes Based on Pure PVdF? Comment on "Self-Suppression of Lithium Dendrite in All-Solid-State Lithium Metal Batteries with Poly(vinylidene difluoride)-Based Solid Electrolytes".

Understanding the Effect of UV-Induced Cross-Linking on the Physicochemical Properties of Highly Performing PEO/LiTFSI-Based Polymer Electrolytes.

We report a thorough, multitechnique investigation of the structure and transport properties of a UV-cross-linked polymer electrolyte based on poly(ethylene oxide), tetra(ethylene glycol)dimethyl ether (G4), and lithium bis(trifluoromethane)sulfonimide. The properties of the cross-linked polymer electrolyte are compared to those of a non-cross-linked sample of same composition. The effect of UV-induced cross-linking on the physico/chemical characteristics is evaluated by X-ray diffraction, differential scanning calorimetry, shear rheology, 1H and 7Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy, 19F and 7Li pulsed field gradient stimulated echo NMR analyses, electrochemical impedance spectroscopy, and Fourier transform Raman spectroscopy. Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number (>0.5) and ionic conductivity (>0.1 mS cm?1) at ambient temperature, by tailoring the structural/morphological characteristics of the polymer matrix. Finally, the polymer electrolyte allows reversible operation with stable profile for hundreds of cycles upon galvanostatic test at ambient temperature of LiFePO4-based lithium-metal cells, which deliver full capacity at 0.05 or 0.1C current rate and keep high rate capabilities up to 1C. This enforces the role of UV-induced cross-linking in achieving excellent electrochemical characteristics, exploiting a practical, easy up-scalable process.

NASICON-type polymer-in-ceramic composite electrolytes for lithium batteries.

Hybrid polymer-ceramic electrolytes with high ceramic loading are currently investigated as a promising solution to achieve high safety and optimal mechanical properties in all-solid-state rechargeable batteries. In this study composite poly(ethylene oxide)/Li1.3Al0.3Ti1.7(PO4)3 (PEO/LATP) electrolytes, with and without lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as the Li+ salt, were investigated through a combination of physicochemical and electrochemical techniques, including X-ray diffraction, scanning electron microscopy, thermal analysis, solid-state MAS-NMR and impedance spectroscopy. We were able to shed light on the interactions between the ceramic and the polymer phases, and on the mechanisms for Li+ transport. Membranes containing 70 wt% of LATP and 30 wt% of P(EO)15LiTFSI exhibit conductivity values of 4 × 10-5 Ω-1 cm-1 at 25 °C and in excess of 10-4 Ω-1 cm-1 at 45 °C. These promising results, obtained on a quasi-ceramic electrolyte through room temperature processing, suggest that further improvements in the transport properties of "polymer-in-ceramic" systems may be sought by increasing the amorphous polymer content, and by carefully investigating the role of the ceramic particles' composition, dimensions and dispersion on the transport properties of the hybrid system.

Enhancing the Pharmaceutical Behavior of Nateglinide by Cocrystallization: Physicochemical Assessment of Cocrystal Formation and Informed Use of Differential Scanning Calorimetry for Its Quantitative Characterization.

The aim of this study was to synthetize cocrystals of nateglinide, an antidiabetic agent of biopharmaceutics classification system Class IIa, as a strategy to improve both the solubility and the dissolution rate of the drug. Benzamide was selected by a screening procedure as a suitable coformer, and binary mixtures with different compositions were prepared and analyzed by differential scanning calorimetry (DSC). An in-depth analysis of DSC data allowed obtaining both the eutectic mixture and cocrystal compositions. The rationale of such an analysis was highlighted and explained. Cocrystals were prepared by kneading and solvent evaporation. Their formation was proved by DSC and confirmed by X-ray powder diffraction, solid-state nuclear magnetic resonance, and Fourier-transform infrared spectroscopy. The functional groups involved in the interaction leading to cocrystals formation were investigated by spectroscopic techniques. The in vitro dissolution profiles show that cocrystals have definite better pharmaceutical performances than the pure drug.

To Which Extent Is Paramagnetic Solid-State NMR Able To Address Polymorphism in Complex Transition-Metal Oxides?

A detailed characterization of the polymorphs constituting cathode materials, both before and after cell cycling, is mandatory to develop more stable and powerful lithium batteries. In many cases, e.g., for transition metal lithium silicates, standard diffraction techniques cannot give a clear-cut response. Here we show that broadband adiabatic fast MAS NMR can give unique information in the case of model Li2(Mn,Fe)SiO4 high-capacity cathode materials. By coupling 7Li and 29Si 1D and 2D spectra, we are able to address polymorphs speciation also in the mixed Mn/Fe compositions, which is a nearly impossible task for X-rays and neutrons diffraction. We finally discuss the conditions under which this approach is useful when applied to rare nuclei such as 29Si.

Multicomponent crystals of gliclazide and tromethamine: preparation, physico-chemical, and pharmaceutical characterization.

OBJECTIVE: To improve the pharmaceutical behavior of the oral antidiabetic agent gliclazide through the synthesis of multicomponent crystals with tromethamine. METHODS: Multicomponent crystals were prepared by solvent evaporation method, kneading, and combining mechanical and thermal activation. DSC, FT-IR spectroscopy, X-ray diffraction, SEM-EDS, and SSNMR were used to investigate their formation. Measurements of solubility and dissolution rate were carried out for the pharmaceutical characterization. RESULTS: The formation of multicomponent crystals of gliclazide and tromethamine was confirmed by all the techniques. In particular, FT-IR and NMR measurements revealed that the interaction between drug and coformer leads to significant changes of the hydrogen bond scheme, and that almost all the functional groups of the two molecules are involved. The dissolution profile of the new phase is significantly better than that of both pure gliclazide and of the reference commercial product Diabrezide®. CONCLUSIONS: The new system shows an improved pharmaceutical behavior and could be formulated in a dosage form to obtain a rapid and complete release of the drug available for absorption.

Polymer and Composite Membranes for Proton-Conducting, High-Temperature Fuel Cells: A Critical Review.

Polymer fuel cells operating above 100 °C (High Temperature Polymer Electrolyte Membrane Fuel Cells, HT-PEMFCs) have gained large interest for their application to automobiles. The HT-PEMFC devices are typically made of membranes with poly(benzimidazoles), although other polymers, such as sulphonated poly(ether ether ketones) and pyridine-based materials have been reported. In this critical review, we address the state-of-the-art of membrane fabrication and their properties. A large number of papers of uneven quality has appeared in the literature during the last few years, so this review is limited to works that are judged as significant. Emphasis is put on proton transport and the physico-chemical mechanisms of proton conductivity.

Covalent and Ionic Functionalization of HLN Layered Perovskite by Sonochemical Methods.

We describe the functionalization of the layered perovskite HLaNb2O7 with n-propanol, n-decanol, 3-mercaptopropyl-trimethoxysilane, imidazole, n-decylamine, and histamine. The use of sonication is found to significantly improve the reaction yield and to reduce the reaction time, compared to conventional thermal treatment under reflux. The obtained intercalates are thoroughly characterized through the use of several complementary experimental techniques (scanning electron microscopy, IR spectroscopy, X-ray diffraction, thermogravimetric analysis, magic-angle spinning NMR), clarifying their structure and chemical bonding. The implications for the design of inorganic-organic composite materials are discussed.