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Materials proposed for the negative electrodes in sodium-ion batteries often include oxides capable of reacting with Na+ through intercalation, conversion, or alloying. While these oxides offer high specific capacities, they suffer from poor mechanical stability. A novel approach to address this issue involves designing tailored nanocomposites based on the (Ti/Sn)Ox system, achieved through partial oxidation of tin-containing MAX phase (Ti3Al(1-x)SnxC2, x = 0.4 and 0.7). By employing this strategy, we have developed composite electrodes based on Ti(1-y)SnyO2 and MAX phase, which exhibit remarkable durability, withstanding over 600 cycles in half-cells. These electrodes also demonstrate charge efficiencies higher than 99.8 % and specific capacities comparable to MXenes electrodes. These outstanding electrochemical performances are further validated at the full-cell level when combined with Na0.44MnO2 positive electrodes. The reaction mechanism between the composite and the sodium ion was also studied using in-situ techniques (Raman and XAS) and the contribution of the different components during sodiation and de-sodiation was highlighted.

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.

Understanding water drop impact on meshes is valuable to design passive systems for atmospheric water collection. By investigating water drop impact on hydrophobic and superhydrophobic surfaces, here, we identify the different drop impact outcomes and build outcome maps within the pertinent parameter spaces, based on Weber number and contact angles. Furthermore, we quantitatively evaluate critical factors such as the captured volume and spray characteristics of the penetrating liquid and also measure the drop rebound time, reporting that full rebound occurs on superhydrophobic meshes surfaces even at high We numbers, as the Cassie-Baxter wetting state is maintained.

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.

Scalable processing of thin and robust solid-electrolyte (SE) separators is key for the commercialization of high-energy all-solid-state batteries (ASSBs). Herein, we report the preparation of Li6PS5Cl-based thin SE separators incorporating suitable binders for potential use in ASSBs by two scalable wet processing techniques: tape-casting with nitrile-butadiene rubber (NBR) and calendering with carboxylated nitrile butadiene rubber (XNBR). By means of tensile testing and electrochemical impedance spectroscopy, the influence of processing on the mechanical as well as the electrochemical properties of the resulting thin SE separators is investigated. A trade-off between the mechanical and electrochemical properties is observed, which is due to the inextricably linked microstructures (particle size, binder content and distribution, and porosity) induced by the two different processes. Thin SE separators prepared using the tape-casting method with the more well-distributed binder network demonstrate superior tensile mechanical properties compared to the ones prepared by the calendering method. The results provide insights into the processing-structure-property relationships of the thin SE separators, which will contribute to advancing the application of practical thin solid electrolytes in ASSBs.

ithium-ion batteries (LIBs) are at the forefront of electrochemical energy storage both for consumer electronics, and for power/energy more demanding applications, such as in automotive and grid levelling. However, their chemical and electrochemical stability must be further improved. Among the instability causes, a major role is played by residual moisture. As a matter of fact, hydrofluoric acid generated by hydrolysis of LiPF6, the most common lithium salt in LIBs, causes safety issues and performance losses. Here we demonstrate the scavenging properties vs. HF of a barium silicate glass used as a filler in a PVDF-HFP based gel polymer electrolyte. A full LiTi2(PO4)3|electrolyte|LiMn2O4 cell is stable for 200 cycles at 0.1C.

The current historical period can be considered a golden age for Lithium-Ion Batteries (LIBs), which accompany our lives from portable devices (e.g. cell phones) to electric vehicles. Unfortunately, the scarsity and univen distribution of some of the raw materials that are mandatory for LIBs' manufacturing means that the growth of this market is threatened. To alleviate this problem, Sodium-Ion Batteries (NIBs) can be introduced to partially substitute LIBs. Some research on new categories of electrode materials is however required to improve NIBs. The research presented here focuses on Nb-based NASICON materials for Sodium-Ion Batteries. As an example, two new phases are proposed: NaFeNb(PO4)3 and NaAlNb(PO4)3. After a facile and reproducible synthesis, the two phases have been studied electrochemically and via operando XAS and XRD, revealing the reaction's kinetics upon sodiation and desodiation.

Batteries are electrochemical devices that have characterized society and its development in recent decades. Moreover, to improve the use of renewable energy sources and electric vehicles, and with the continuous growth of the demand for portable electronics, the demand for batteries that can meet global needs has increased. Currently, the most widely used type of them is the lithium-ion battery (LIB), which is reliable and provides satisfying electrochemical performances[1]. However, the most used anode in this system is the graphite anode (theoretical capacity of 370 mAh g-1), which suffers from aging and becomes unsafe with high currents. So, it is important to investigate other types of materials as possible and promise anode that could give better properties. MAX phase (where M is a transition metal cation, A is a metallic or metalloid element and X is C, N or B) are a class of 3D materials, with layered hexagonal crystal structure (space group P63/mmc) consisting of several layers of MX, alternated with layers of pure A-elements along the c cell parameter[2]. One of the most common of this class of materials is the Ti3AlC2 MAX phase. However, it shows poor energy storage performances as active electrode (capacity of 60 mAh g-1). One compound well-known as active material is titanium oxide (TiO2). This has been shown to be a well-established and particularly stable material for applications in ion batteries. However, it has a lower capacity than graphite[3]. One interesting material as electrode is tin oxide (SnO2): this is a very promising material due to its high specific capacity, but it suffers from poor stability due to the high volume change it undergoes during charge and discharge cycles[4]. A possible strategy to improve the long-term stability of this oxide is to use the stable titanium oxide with it: is reported that by adding it, making a solid solution of Sn/Ti oxide, the total system achieves less volume change during cycling and so gains a stabili

Batteries are electrochemical devices that have characterized society and its development in recent decades. Moreover, to improve the use of renewable energy sources and electric vehicles, and with the continuous growth of the demand for portable electronics, the demand for batteries that can meet global needs has increased. Currently, the most widely used type of them is the lithium-ion battery (LIB), which is reliable and provides satisfying electrochemical performances. However, the most used anode in this system is the graphite anode (theoretical capacity of 370 mAh g-1 ), which suffers from aging and becomes unsafe with high currents. So, it is important to investigate other types of materials as possible and promise anode that could give better properties. MAX phase (where M is a transition metal cation, A is a metallic or metalloid element and X is C, N or B) are a class of 3D materials, with layered hexagonal crystal structure (space group P63/mmc) consisting of several layers of MX, alternated with layers of pure A-elements along the c cell parameter. One of the most common of this class of materials is the Ti3AlC2 MAX phase. However, it shows poor energy storage performances as active electrode (capacity of 60 mAh g-1). One compound well-known as active material is titanium oxide (TiO2). This has been shown to be a well-established and particularly stable material for applications in ion batteries. However, it has a lower capacity than graphite. One interesting material as electrode is tin oxide (SnO2): this is a very promising material due to its high specific capacity, but it suffers from poor stability due to the high volume change it undergoes during charge and discharge cycles. A possible strategy to improve the long-term stability of this oxide is to use the stable titanium oxide with it: is reported that by adding it, making a solid solution of Sn/Ti oxide, the total system achieves less volume change during cycling and so gains a stability improvem

Aqueous electrolytes in the form of highly concentrated solutions stand as a viable alternative to the organic counterpart as battery electrolytes thanks to the low flammability, toxicity, cost and large availability, while keeping good potential windows. In this work, a half-cell constituted of lithium titanium phosphate in a binary aqueous solution of sodium acetate (7 mol kg(-1)) and potassium acetate (20 mol kg(-1)) as a promising anode for sodium-ion batteries is characterized with constant current, static and dynamic electrochemical impedance spectroscopy to reveal its thermodynamic and kinetic properties. The experiments permit to withdraw some information on the thermodynamics (activation energy of processes) and kinetics (processes' parameters evolution) of the system. Physical information was extracted from impedance spectra with mathematical regression of a porous electrode intercalation model available in literature using an innovative procedure of batch-fitting of a complete set of spectra at once. The advantage and shortcoming on using impedance in battery-development is discussed.

Lithium-ion batteries are constantly developing as the demands for power and energy storage increase. One promising approach to designing high-performance lithium-ion batteries is using conversion/alloying materials, such as SnO2. This class of materials does, in fact, present excellent performance and ease of preparation; however, it suffers from mechanical instabilities during cycling that impair its use. One way to overcome these problems is to prepare composites with bi-dimensional materials that stabilize them. Thus, over the past 10 years, two-dimensional materials with excellent transport properties (graphene, MXenes) have been developed that can be used synergistically with conversion materials to exploit both advantages. In this work, a 50/50 (by mass) SnO2/Ti3C2Tz nanocomposite is prepared and optimized as a negative electrode for lithium-ion batteries. The nanocomposite delivers over 500 mAh g−1 for 700 cycles at 0.1 A g−1 and demonstrates excellent rate capability, with 340 mAh g−1 at 8 A g−1. These results are due to the synergistic behavior of the two components of the nanocomposite, as demonstrated by ex situ chemical, structural, and morphological analyses. This knowledge allows, for the first time, to formulate a reaction mechanism with lithium-ions that provides partial reversibility of the conversion reaction with the formation of SnO.

New generation lithium batteries require better performances, improved safety, and sustainability. Better performances can be obtained with lithium anodes and high-voltage cathodes, which in turn pose more pressure on the electrolyte stability, which is mandatory for safety. Deep Eutectic Solvents (DESs) are promising components for safer and more environmentally sustainable electrolytes. We investigate the physico-chemical properties of DESs made with 2,2,2-trifluoroacetamide (TFA) and LiPF6. The best composition is tested against Li metal and two cathode active materials: LiFePO4 (LFP) and high voltage LiNi1-x-yMnxCoyO2 (NMC). We obtain good electrochemical performance in a Li-metal cell with LFP. Accelerated rate calorimetry shows improved thermal stability of the Li|DES|NMC cell with respect to a commercial liquid electrolyte.

MXenes are an emerging class of materials considered for many applications, such as sensors, catalysis, energy storage devices. The main obstacle towards their massive implementation is the synthesis requiring the direct use of HF as etching agent. The development of alternative synthetic routes exploiting in-situ forming HF agents is the main strategies to overcome this limitation. In this study four different etching methods based on the use of NH4HF2, NaF−HCl, HBF4, and NaBF4−HCl are compared to produce Ti3C2Tx from Ti3AlC2 towards the application of MXenes in sodium ion batteries. Three of such etching methods have already been reported while one is here presented for the first time. The structural analysis of the obtained products is based on X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and X-ray photoelectron spectroscopy (XPS) analysis. All the materials have been tested in half-cell configuration vs. Na; the charge/discharge profiles and the C-rate tests are discussed and related to specific structural features. Overall, the results reveal that the MXene obtained using the HBF4 etching agent under mild conditions is comparable both in structure and functional properties to the benchmark material, i. e., the MXene produced using HF at 5 % concentration. Indeed, the MXene synthetized with the HBF4 presents the lowest mean voltage and potential hysteresis and shows the highest first cycle efficiency (69.7 %), overcoming the performance of the MXene produced with 5 % HF (67 %). This study proves the possibility to produce MXene with a more sustainable route.

Hybrid silica-based nanofillers were synthesised by grafting short chains of poly(ethylene glycol) (PEG) with different molecular weight on the surface of SiO2 porous nanoparticles. Based on this approach, homogeneous poly(ethylene oxide) (PEO)-based ceramic-in-polymer solid-state electrolytes with SiO2 loadings up to 23 wt% were obtained, thanks to the high compatibility between the two phases endowed by the grafted PEG chains. These electrolytes showed satisfying ionic conductivity and excellent resistance against dendrite piercing that enabled long operation, for more than 350 h, under continuous stripping/plating of lithium in symmetric Li/electrolyte/Li cells. Additionally, the operating life of these devices was improved by the self-healing reaction between Li dendrites and silica fillers, being able to reinstate the cycling after short circuit. Finally, a lithium metal full cell, equipped with LiFePO4 positive material and the solid-state electrolyte containing 18 wt% of SiO2, demonstrated high stability against dendrite penetration and discharge capacity at 70 °C comparable to cells based on liquid analogues.

Batteries based on organic electrolytes have been raising safety concerns due to some associated fire/explosion accidents caused by the unusual combination of highly flammable organic electrolytes and high energy electrodes. Nonflammable aqueous batteries are a good alternative to the current energy storage systems. However, what makes aqueous batteries safe and viable turns out to be their main weakness, since water molecules are prone to decomposition because of a narrow electrochemical stability window (ESW). In this perspective we introduce aqueous batteries and then discuss the state-of-the-art of water-in-salt (WIS) electrolytes for aqueous energy storage systems. The main strategies to improve ESW are reviewed, including: (i) the use of fluorinated salts to make a solid electrolyte interphase (SEI); (ii) the use of cost-effective and highly soluble salts to reduce water activity through super concentration; and (iii) the use of hybrid electrolytes combining the advantages of both aqueous and non-aqueous phases. Then, we discuss different battery chemistries operated with different WIS electrolytes. Finally, we highlight the challenges and future technological perspectives for practical aqueous energy storage systems, including applications in stationary storage/grid, power backup, portable electronics, and automotive sectors.

Among all the possibilities for next-generation rechargeable batteries, lithium metal is still craved as the Holy Grail of negative electrode materials, for the high theoretical specific capacity, the lowest redox potential, and the superior energy density with respect to currently used Li-ion batteries. Such energy density can be further increased by studying the anodeless configuration: the cell setup consists of a bare copper current collector where the lithium is plated directly from the cathode. Unfortunately, lithium plating/stripping on high-area surfaces displays a series of well-known problems: unstable SEI, dendrites formation that leads to cell short-circuit, and dead-lithium formation that causes severe capacity fading. In this respect, a lot of interesting strategies have been proposed; the ones adopted in this study are the electrolyte design and the employment of engineered current collectors. For this research, the effect of three different liquid electrolytes was studied on symmetrical Li|Li coin cells: commercial LP30, a Deep Eutectic Solvent and a Dual Salt electrolyte have been employed in the first part. while using the commercial LP30 and the DES the cell overpotential escalates as the cycles increase, with the DS the cyclic potential profile remains stable between ±0.02 V even after 200 cycles, confirming the validity of such electrolyte in the formation of a stable SEI. SEM measurements of the plated lithium surfaces have confirmed this stabilizing effect and its repercussions on the lithium morphology. In the second part, the DS performance has been measured in a non-symmetrical configuration to study the effect of the current collector: Cu|Li coin cells have been used for anodeless plating and stripping. As preliminary measurements, both the smooth and the rough sides of a plain Cu foil have been tested; the coins with rough Cu have displayed the most stable potential profiles and the highest Coulombic efficiencies. This is believed to be a

Among the materials for the negative electrodes in Li-ion batteries, oxides capable of reacting with Li+ via intercalation/conversion/alloying are extremely interesting due to their high specific capacities but suffer from poor mechanical stability. A new way to design nanocomposites based on the (Ti/Sn)O2 system is the partial oxidation of the tin-containing MAX phase of Ti3Al(1-x)SnxO2 composition. Exploiting this strategy, this work develops composite electrodes of (Ti/Sn)O2 and MAX phase capable of withstanding over 600 cycles in half cells with charge efficiencies higher than 99.5% and specific capacities comparable to those of graphite and higher than lithium titanate (Li4Ti5O12) or MXenes electrodes. These unprecedented electrochemical performances are also demonstrated at full cell level in the presence of a low cobalt content layered oxide and explained through an accurate chemical, morphological, and structural investigation which reveals the intimate contact between the MAX phase and the oxide particles. During the oxidation process, electroactive nanoparticles of TiO2 and Ti(1-y)SnyO2 nucleate on the surface of the unreacted MAX phase which therefore acts both as a conductive agent and as a buffer to preserve the mechanical integrity of the oxide during the lithiation and delithiation cycles.

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.

Dynamic Electrochemical Impedance Spectroscopy is a valuable tool to investigate kinetic parameters of non-Faradic processes in symmetric Electrochemical Double Layer Capacitors. Compared to classic Electrochemical Impedance Spectroscopy, the dynamic technique measures the impedance under non-equilibrium condition removing the stationarity requirement and, at the same time, giving the frequency-dependent information of a dynamic process in presence of overpotential. Despite not being a new technique, there is an inherent complexity in the signal sampling and data manipulation to obtain the impedance spectra down to low frequencies (the interesting band for energy storage devices impedance). Few methods to compute the impedance from sampled signals are reported in the literature and under development. For this work the Dynamic Multi-Frequency Analysis algorithm was used to compute the impedance and reconstruct the cyclic voltammetry profile as well. The time-dependency of the kinetic parameters, namely capacitances of double layer and adsorption phenomenon, were extracted from equivalent circuit model regression and the adsorption time constants with a graphical analysis of the impedance spectra dataset during a full charge/discharge cycle. The values of the adsorption capacitance from the model regression are, on average, compatible with the values computed with a common formula showing the reliability of the model regression. The use of a three-electrode compact cell allowed the characterization of both active electrodes independently during operation showing a strong potential dependence on the active material properties. Furthermore, the impedance showed the presence of a side reaction (likely oxygen evolution) connected to the increase of adsorption and double layer capacitances localized on the positive electrode in a clearer way than what was possible to observe from the voltametric profile.

Sodium-ion batteries have recently aroused the interest of industries as possible replacements for lithium-ion batteries in some areas. With their high theoretical capacities and competitive prices, P2-type layered oxides (NaxTMO2) are among the obvious choices in terms of cathode materials. On the other hand, many of these materials are unstable in air due to their reactivity toward water and carbon dioxide. Here, Na0.67Mn0.9Ni0.1O2 (NMNO), one of such materials, has been synthesized by a classic sol-gel method and then exposed to air for several weeks as a way to allow a simple and reproducible transition toward a Na-rich birnessite phase. The transition between the anhydrous P2 to the hydrated birnessite structure has been followed via periodic XRD analyses, as well as neutron diffraction ones. Extensive electrochemical characterizations of both pristine NMNO and the air-exposed one vs sodium in organic medium showed comparable performances, with capacities fading from 140 to 60 mAh g-1 in around 100 cycles. Structural evolution of the air-exposed NMNO has been investigated both with ex situ synchrotron XRD and Raman. Finally, DFT analyses showed similar charge compensation mechanisms between P2 and birnessite phases, providing a reason for the similarities between the electrochemical properties of both materials.

P’2-Na0.67Mn0.67Ni0.33O2 (NMNO) is one of the most promising cathodic materials for new generation sodium-ion batteries (SIBs). One drawback that is preventing its commercialization is however the high instability in the potential window 2.5–4.5 V vs. Na+/Na, caused by degradation reactions affecting the material's structure and composition. Herein we propose a strategy to overcome this weak spot introducing the surface coating of the material particles with inert magnesium oxide, that has been chosen as coating agent because of its low molecular weight. This protective layer is able to reduce the structural instability of the material without modifying the mixed conduction properties and thus globally stabilizing the electrochemical performances. In fact, the electrode of NMNO coated with 7 % of MgO, after an initial stabilization, was able to deliver over 90 mAh g−1 of reversible specific capacity at a current value of 50 mA g−1, with a capacity retention of 70 % after 250 cycles, to be compared with the 30 mAh g−1 of the uncoated material. The effect of the coating on the particles surface is here investigated with differential electrochemical mass spectrometry, to analyze the influence of the treatment on the electrode/electrolyte interphase.

Extended interphases are playing an increasingly important role in electrochemical energy storage devices and, in particular, in lithium-ion and lithium metal batteries. With this in mind we initially address the differences between the concepts of interface and interphase. After that, we discuss in detail the mechanisms of solid electrolyte interphase (SEI) formation in Li-ion batteries. Then, we analyze the methods for interphase characterization, with emphasis put on in-situ and operando approaches. Finally, we look at the near future by addressing the issues underlying the lithium metal/electrolyte interface, and the emerging role played by the cathode electrolyte interphase when high voltage materials are employed.

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).

There is a growing demand of electrochemical energy storage, driven by automotive and stationary requirements. Lithium-ion batteries (LIBs) are expected to dominate the market from the current 0.5TWh to about 2.5TWh in 2030. This will lead to great difficulties in the procurement of critical raw materials and in the management of end-of-life systems. From a circular economy perspective, it is necessary to identify reuse and recycling strategies that can make the demand fully sustainable. However, second life and recycling are not mutually excluding, while the final fate of the battery, or at least of its noblest components, should be recycling instead of disposal. In this context, to allow new strategies such as direct recycling of cathode powders, an accurate redesign of the battery system, from the single cell to the modules, which allows ease of separation of the compartments, should be considered. The correct evaluation of the best strategies cannot be separated from an accurate and transparent life cycle assessment (LCA), which would take into account both economic and environmental aspects. Herein, the most advanced recycling methods are analyzed and the issues underlying the efficient reuse and recycling of battery packs from electric vehicles are critically discussed.

The paper reports and comments the results of several electron spin resonance investigations, performed on semiconductor oxides for gas sensing. The main aspects, related to the comparison between spectroscopic and electric data, are concerning on (i) the role of the oxide defects in interacting with the gas atmosphere; (ii) the origin of the sensing enhancement, which follows the doping of the oxide by transition metal ions; and (iii) the effects of different particle morphology and of the controlled particle shape on the sensing functionality. The electron spin resonance results have been associated, when possible, to those deriving from X-ray photoelectron spectroscopy, in order to investigate the electronic configuration of the transition metal centers. Special emphasis has been deserved to the oxide synthesis procedures, in several cases well related to the electrical response. The data have been drawn from several studies, performed in different time periods, and have been compared to suggest a possible common interpretation of the sensing mechanism, based on either electronic or morphological properties.

Luminescent solar concentrators (LSCs) are rapidly emerging as the key enabling technology towards the realization of zero-energy buildings. The development of new efficient and sustainable luminophores is crucial for further improvement. The large Stokes shift, luminescent and persistent radicals prepared using sustainable routes offer advantages for large-area transparent LSCs featuring minimal colour distortion of the transmitted light. LSCs based on the best performing luminescent radicals are largely unaffected by reabsorption losses, thus providing a better performance with respect to the literature standards over active areas exceeding 400 cm2.