Design and development of solid-state functional materials for Na-ion batteries

This Thesis addresses new functional materials for Na-ion battery (NIB) applications. Since the breakthrough of Li-ion battery (LIB), extensive research has been focusing on alternatives to Lithium, based on cheaper and widespread elements for sustainable energy storage solutions. In this context, the effective large-scale deployment of NIB requires great efforts in the development of good Na+ host anodes, high-energy cathodes and safe electrolytes. New components must ensure enhanced efficiency in the NIB operating processes (i.e., Na+ insertion/extraction at the electrode/electrolyte interface and Na+ transport through the electrolyte) for empowering high energy density and long-term cycle stability. Here, we present NIB materials optimization through an innovative approach, based on computational methods that are directly related to experiments. Our aim is to unveil the most important features that can affect the material capabilities towards Na+ uptake, transport and storage. During the research activity at Università di Napoli Federico II, state-of-the-art DFT methods have been employed to investigate the structure-property relationship of solid-state nanoelectrodes. Our studies on TiO2 anatase and MoS2/graphene 2D-heterostructure reveals that sodiation mechanisms are driven by intrinsic structural features. Migration barriers are directly correlated to structure-dependent descriptors, such as the accessible area for the intercalating Na+ at TiO2 surfaces, and the S coordination around the migrating Na+ within MoS2/graphene interface. From these outcomes, we provide new design strategies to improve the electrode efficiency upon sodiation, for example suggesting the preferential growth of TiO2 along the (001) direction or the introduction of S vacancies in MoS2 monolayers. On the cathode side, we unveil the charge compensation mechanism occurring in NaxNi0.25Mn0.68O2 upon desodiation, with a major focus on the O-redox chemistry at very low Na loads. Molecular O2 is predicted to be released from Mn-deficient sites in the bulk cathode via formation of superoxo-species and preferential breaking of labile Ni-O bonds. We prove that increasing M-O covalency via suitable doping would prevent O2 loss and allows to fully recover a reversible process. Research stages at ENS de Lyon and the R&D laboratory of Lithops s.r.l. have been dedicated to the optimization of electrolyte materials. By development and application of polarizable force fields in molecular dynamics simulations, we report reliable predictions of Na+ diffusion and solvation properties into the PyrFSI room-temperature ionic liquid (RT-IL). We combine RT-ILs with cross-linked PEO matrix to obtain highly conductive polymeric membranes. Galvanostatic cycling of Na metal based cells containing these innovative polymer electrolytes and state-of-the-art electrodes shows promising performances and paves the route to further assessment of efficient cells. The foreseen integration of these studies will provide new understanding on the complex charge transfer processes occurring at the electrode/electrolyte interface during battery functioning. The new knowledge on electrochemical behavior of advanced materials will be key for boosting the NIB technology in the near future

Unveiling Oxygen Redox Activity in P2-Type NaxNi0.25Mn0.68O2 High-Energy Cathode for Na-Ion Batteries

Na-ion batteries are emerging as convenient energy-storage devices for large-scale applications. Enhanced energy density and cycling stability are key in the optimization of functional cathode materials such as P2-type layered transition metal oxides. High operating voltage can be achieved by enabling anionic reactions, but irreversibility of O2–/O2n–/O2 evolution still limits this chance, leading to extra capacity at first cycle that is not fully recovered. Here, we dissect this intriguing oxygen redox activity in Mn-deficient NaxNi0.25Mn0.68O2 from first-principles, by analyzing the formation of oxygen vacancies and dioxygen complexes at different stages of sodiation. We identify low-energy intermediates that release molecular O2 at high voltage, and we show how to improve the overall cathode stability by partial substitution of Ni with Fe. These new atomistic insights on O2 formation mechanism set solid scientific foundations for inhibition and control of this process toward the rational design of new anionic redox-active cathode materials

Tai Chi Enhances the Effects of Endurance Training in the Rehabilitation of Elderly Patients with Chronic Heart Failure

Purpose. To assess if Tai Chi added to endurance training (ET) is more effective than ET alone in improving exercise tolerance and quality of life (QOL) of elderly patients with chronic heart failure (CHF). Design. Sixty CHF patients, age 73.8 ± 6 years, M/F 51/9, were enlisted. Thirty pts were randomized to combined training (CT) performing Tai Chi +ET and 30 patients to ET (ET only). Methods. At baseline and after 12 weeks all patients underwent 6-minute walking test (6MWT), assessment of amino terminal probrain natriuretic peptide (NT-pro BNP), quadriceps maximal voluntary contraction (MVC) and peak torque (PT), QOL questionnaire (MacNewQLMI), blood pressure (BP), and heart rate (HR). All patients performed 4 sessions of exercise/week. Results. Distance at 6mwt improved in both groups with significant between-groups differences (P = .031). Systolic BP and NT-proBNP decreased significant in the CT group compared to ET (P = .025) and P = .015), resp.). CT group had a greater significant improvement in physical perception (P = .026) and a significant increase of PT compared to ET group. Conclusions. The association of Tai Chi and ET improves exercise tolerance and QOL of patients with CHF more efficiently than ET

Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

In this manuscript, we report a detailed physico-chemical comparison between the - and -polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic -NaMnO2 shows larger reversible capacity exceeding 175 mAhg-1 at 10 mAg-1

d-Glucose Adsorption on the TiO2 Anatase (100) Surface: A Direct Comparison Between Cluster-Based and Periodic Approaches

Titanium dioxide (TiO2) has been extensively studied as a suitable material for a wide range of fields including catalysis and sensing. For example, TiO2-based nanoparticles are active in the catalytic conversion of glucose into value-added chemicals, while the good biocompatibility of titania allows for its application in innovative biosensing devices for glucose detection. A key process for efficient and selective biosensors and catalysts is the interaction and binding mode between the analyte and the sensor/catalyst surface. The relevant features regard both the molecular recognition event and its effects on the nanoparticle electronic structure. In this work, we address both these features by combining two first-principles methods based on periodic boundary conditions and cluster approaches (CAs). While the former allows for the investigation of extended materials and surfaces, CAs focus only on a local region of the surface but allow for using hybrid functionals with low computational cost, leading to a highly accurate description of electronic properties. Moreover, the CA is suitable for the study of reaction mechanisms and charged systems, which can be cumbersome with PBC. Here, a direct and detailed comparison of the two computational methodologies is applied for the investigation of d-glucose on the TiO2 (100) anatase surface. As an alternative to the commonly used PBC calculations, the CA is successfully exploited to characterize the formation of surface and subsurface oxygen vacancies and to determine their decisive role in d-glucose adsorption. The results of such direct comparison allow for the selection of an efficient, finite-size structural model that is suitable for future investigations of biosensor electrocatalytic processes and biomass conversion catalysis.</p

New Acquisition Protocol of 18 F-Choline PET/CT in Prostate Cancer Patients: Review of the Literature about Methodology and Proposal of Standardization

. Purpose. (1) To evaluate a new acquisition protocol of 18 F-choline (FCH) PET/CT for prostate cancer patients (PC), (2) to review acquisition 18 F-choline PET/CT methodology, and (3) to propose a standardized acquisition protocol on FCH PET/CT in PC patients. Materials. 100 consecutive PC patients (mean age 70.5 years, mean PSA 21.35 ng/mL) were prospectively evaluated. New protocol consisted of an early scan of the pelvis immediately after the injection of the tracer (1 bed position of 4 min) followed by a whole body scan at one 1 hour. Early and 1 hour images were compared for interfering activity and pathologic findings. Results. The overall detection rate of FCH PET/CT was 64%. The early static images of the pelvis showed absence of radioactive urine in ureters, bladder, or urethra which allowed a clean evaluation of the prostatic fossae. Uptake in the prostatic region was better visualized in the early phase in 26% (7/30) of cases. Other pelvic pathologic findings (bone and lymph nodes) were visualized in both early and late images. Conclusion. Early 18 F-choline images improve visualization of abnormal uptake in prostate fossae. All pathologic pelvic deposits (prostate, lymph nodes, and bone) were visualized in both early and late images

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Un approccio analitico basato su pirolisi, gas cromatografia e spettrometria di massa (Py-GC/MS, EGA-MS, GC/MS) allo studio della conversione catalitica di fruttosio e inulina a HMF

Lo studio ha riguardato l'analisi in pirolisi di fruttosio, inulina e topinambour per valutare le differenze dovute alla presenza di catalizzatori inorganici. In parallelo sono state svolte analisi di caratterizzazione di sottoprodotti di reazione del fruttosio e dell'inulina a dare HMF

Fructose and inulin: Behaviour under analytical pyrolysis

EGA-MS (evolved gas analysis-mass spectrometry) and Py(HMDS)-GC/MS (pyrolysis-gas chromatography coupled with mass spectrometry with in situ derivatisation using hexamethyldisilazane as a silylating agent) were used to study the behaviour under pyrolytic conditions of fructose, inulin and topinambour (Jerusalem artichoke), a tuber, in which inulin coexists with other organic and inorganic species. The aim was to acquire a complete picture of the chemical characteristics and reactivity of fructose and its polymers (fructans). In fact, fructans constitute the reserve carbohydrates of several botanical species and are important substrates for obtaining high value-added products. EGA-MS of inulin and topinambour provided information on their different thermal and chemical complexities. Despite tuber being constituted mostly by inulin, its thermogram was much more complex than obtained for inulin alone. The EGA curve of topinambour extended for a wider temperature range and provided mass spectra containing several peaks related to the fragmentation of compounds different from those obtained in the analysis of inulin. The evolution of levoglucosan clearly indicates the presence of glucose units in the tuber. The pyrolysis of fructose and inulin carried out by Py-GC/MS generated a high number of pyrolysis products, the main ones being dihydroxyacetone, 5-hydroxymethyl-2-furaldehyde, and 2,6-anhydrofructofuranose. The similarity between the two pyrograms suggests that under pyrolysis conditions, one of the first reactions of inulin is the cleavage of the glycosidic bond. An important difference was obtained in the pyrolysis of inulin alone, which led to the formation of di-fructose dianhydrides. A different quali-quantitative distribution of the pyrolysis products was obtained for topinambour likely due to the different monosaccharides in the topinambour composition from fructose, as well as to the presence of significant amounts of inorganics