Investigation of Mn and Fe Substitution Effects on the Characteristics of High-Voltage LiCo1–xMxPO4 (x=0.1, 0.4) Cathodes Prepared by Sol–gel Route

Herein, we provide a fundamental study revealing the substantial changes promoted by manganese and iron substitution for cobalt in a high-voltage LiCoPO4 olivine cathode. Therefore, LiCoPO4, LiCo0.9Fe0.1PO4, LiCo0.6Fe0.4PO4, LiCo0.9Mn0.1PO4, and LiCo0.6Mn0.4PO4 are synthesized by a sol–gel pathway and comparatively investigated in terms of structure, morphology, and electrochemical features in lithium battery. Besides the observed effects on structure, particle size, and metals distribution, the work reveals a gradually enhancing electrode reaction by increasing the Fe content in LiCo0.9Fe0.1PO4 and LiCo0.6Fe0.4PO4, with Co3+/Co2+ and Fe3+/Fe2+ signatures at 4.8 and 3.5 V vs Li+/Li, respectively. On the other hand, the introduction of Mn leads to a progressive electrode deactivation in LiCo0.9Mn0.1PO4 and LiCo0.6Mn0.4PO4 due to an intrinsic hindering of the Mn3+/Mn2+ process at 4.1 V vs Li+/Li. The reasons accounting for such an intriguing behavior are investigated in detail using electrochemical impedance spectroscopy within the potential range of the redox processes. The study reveals that manganese and iron substitutions in the high-voltage olivine have opposite effects on the charge transfer resistance, i.e., detrimental for the former while beneficial for the latter, with remarkable enhancement of the reversible capacity, the Coulombic efficiency, and the cycle life. Such results provide to the scientific community useful information on possible strategies to enhance the emerging LiCoPO4 high-voltage electrode by transition metal substitution

Characteristics of a gold-doped electrode for application in high-performance lithium-sulfur battery

Bulk sulfur incorporating 3 wt% gold nano-powder is investigated as possible candidate to maximize the fraction of active material in the Li-S battery cathode. The material is prepared via simple mixing of gold with molten sulfur at 120 °C, quenching at room temperature, and grinding. Our comprehensive study reports relevant electrochemical data, advanced X-ray computed tomography (CT) imaging of the positive and negative electrodes, and a thorough structural and morphological characterization of the S:Au 97:3 w/w composite. This cathode exhibits high rate capability within the range from C/10 to 1C, a maximum capacity above 1300 mAh gS−1, and capacity retention between 85% and 91% after 100 cycles at 1C and C/3 rates. The novel formulation enables a sulfur fraction in the composite cathode film as high as 78 wt%, an active material loading of 5.7 mg cm−2, and an electrolyte/sulfur (E/S) ratio of 5 μL mg−1, which lead to a maximum areal capacity of 5.4 mAh cm−2. X-ray CT at the micro- and nanoscale reveals the microstructural features of the positive electrode that favor fast conversion kinetics in the battery. Quantitative analysis of sulfur distribution in the porous cathode displays that electrodeposition during the initial cycle may trigger an activation process in the cell leading to improved performance. Furthermore, the tomography study reveals the characteristics of the lithium anode and the cell separator upon a galvanostatic test prolonged over 300 cycles at a 2C rate

Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X-Ray Tomography at the Nanoscale

The degradation mechanism in a sodium cell of a layered Na0.48Al0.03Co0.18Ni0.18Mn0.47O2 (NCAM) cathode with P3/P2 structure is investigated by revealing the changes in microstructure and composition upon cycling. The work aims to rationalize the gradual performance decay and the alteration of the electrochemical response in terms of polarization, voltage signature, and capacity loss. Spatial reconstructions of the electrode by X-ray computed tomography at the nanoscale supported by quantitative and qualitative analyses show fractures and deformations in the cycled layered metal-oxide particles, as well as inorganic side compounds deposited on the material. These irreversible morphological modifications reflect structural heterogeneities across the cathode particles due to formation of various domains with different Na+ intercalation degrees. Besides, X-ray photoelectron spectroscopy data suggest that the latter inorganic species in the cycled electrode are mainly composed of NaF, Na2O, and NaCO3 formed by parasitic electrolyte decomposition. The precipitation of these insulating compounds at the electrode/electrolyte interphase and the related structural stresses induced in the material lead to a decrease in cathode particle size and partial loss of electrochemical activity. The retention of the NCAM phase after cycling suggests that electrolyte upgrade may improve the performance of the cathode to achieve practical application for sustainable energy storage

The role of synthesis pathway on the microstructural characteristics of sulfur-carbon composites: X-ray imaging and electrochemistry in lithium battery

Two synthesis pathways are adopted to tune the microstructural characteristics of sulfur-carbon (S-C) composites for application in lithium-sulfur (Li-S) batteries. Both methods include intimate mixing of either carbon black or multiwalled carbon nanotubes with elemental sulfur, molten according to the first approach while dispersed in alcohol and heated according to the second one. Nano- and micro-scale X-ray computed tomography supported by X-ray diffraction and electron microscopy shows materials consisting of crystalline sulfur clusters (70 wt%) with size ranging from about 5 to 50 μm, surrounded by carbon. The sulfur cluster size appears limited by direct mixing of molten sulfur and carbons, in particular when carbon black is employed, whilst it is increased by exploiting the alcohol dispersion. Electrochemistry reveals that small sulfur particles lead to an improved rate capability in Li-S cells, whereas large active material domains may favor the capacity retention. The composites using carbon black nanoparticles exhibit the highest reversible capacity, with a maximum value exceeding 1500 mAh gS−1, whereas the composites involving multiwalled carbon nanotubes show the best capacity retention, with values approaching 70% over 150 cycles. Our multi-disciplinary approach will shed light on significant aspects aiming to enhance the Li-S battery and favor a practical application

Thermodynamic Forecasts of the Mediterranean Sea Acidification

Anthropogenic CO2 is a major driver of the present ocean acidification. This latter is threatening the marine ecosystems and has been identified as a major environmental and economic menace. This study aims to forecast from the thermodynamic equations, the acidification variation (ΔpH) of the Mediterranean waters over the next few decades and beyond this century. In order to do so, we calculated and fitted the theoretical values based upon the initial conditions from data of the 2013 MedSeA cruise. These estimates have been performed both for the Western and for the Eastern basins based upon their respective physical (temperature and salinity) and chemical (total alkalinity and total inorganic carbon) properties. The results allow us to point out four tipping points, including one when the Mediterranean Sea waters would become acid (pH<7). In order to provide an associated time scale to the theoretical results, we used two of the IPCC (2007) atmospheric CO2 scenarios. Under the most optimistic scenario of the “Special Report: Emissions Scenarios” (SRES) of the IPCC (2007), the results indicate that in 2100, pH may decrease down to 0.245 in the Western basin and down to 0.242 in the Eastern basin (compared to the pre-industrial pH). Whereas for the most pessimistic SRES scenario of the IPCC (2007), the results for the year 2100, forecast a pH decrease down to 0.462 and 0.457, for the Western and for the Eastern basins, respectively. Acidification, which increased unprecedentedly in recent years, will rise almost similarly in both Mediterranean basins only well after the end of this century. These results further confirm that both basins may become undersaturated (< 1) with respect to calcite and aragonite (at the base of the mixed layer depth), only in the far future (in a few centuries)

A New CuO-Fe₂O₃ ‐Mesocarbon Microbeads Conversion Anode in a High‐Performance Lithium‐Ion Battery with a Li₁.₃₅Ni₀.₄₈Fe₀.₁Mn₁.₇₂O₄ Spinel Cathode

A ternary CuO-Fe₂O₃ ‐mesocarbon microbeads (MCMB) conversion anode was characterized and combined with a high‐voltage Li₁.₃₅Ni₀.₄₈Fe₀.₁Mn₁.₇₂O₄ spinel cathode in a lithium‐ion battery of relevant performance in terms of cycling stability and rate capability. The CuO-Fe₂O₃-MCMB composite was prepared by using high‐energy milling, a low‐cost pathway that leads to a crystalline structure and homogeneous submicrometrical morphology as revealed by XRD and electron microscopy. The anode reversibly exchanges lithium ions through the conversion reactions of CuO and Fe₂O₃ and by insertion into the MCMB carbon. Electrochemical tests, including impedance spectroscopy, revealed a conductive electrode/electrolyte interface that enabled the anode to achieve a reversible capacity value higher than 500 mAh g⁻¹ when cycled at a current of 120 mA g⁻¹. The remarkable stability of the CuO-Fe₂O₃-MCMB electrode and the suitable characteristics in terms of delivered capacity and voltage‐profile retention allowed its use in an efficient full lithium‐ion cell with a high‐voltage Li₁.₃₅Ni₀.₄₈Fe₀.₁Mn₁.₇₂O₄ cathode. The cell had a working voltage of 3.6 V and delivered a capacity of 110 mAh g_{cathode}⁻¹ with a Coulombic efficiency above 99 % after 100 cycles at 148 mA g_{cathode}⁻¹. This relevant performances, rarely achieved by lithium‐ion systems that use the conversion reaction, are the result of an excellent cell balance in terms of negative‐to‐positive ratio, favored by the anode composition and electrochemical features

Biochemical Diagnosis of a Fatal Case of Günther’s Disease in a Newborn with Hydrops Foetalis

Peer Reviewe

Prediabetes management in the Middle East, Africa and Russia: Current status and call for action:

Most data on the burden of diabetes and prediabetes are from countries where local infrastructure can support reliable estimates of the burden of non-communicable diseases. Countries in the Middle ..

Long-term effectiveness of unboosted atazanavir plus abacavir/lamivudine in subjects with virological suppression: A prospective cohort study

Effectiveness data of an unboosted atazanavir (ATV) with abacavir/lamivudine (ABC/3TC) switch strategy in clinical routine are scant.We evaluated treatment outcomes of ATV + ABC/3TC in pretreated subjects in the EuroSIDA cohort when started with undetectable plasma HIV-1 viral load (pVL), performing a time to loss of virological response (TLOVR 50 copies/mL.We included 285 subjects, 67% male, with median baseline CD4 530 cells, and 44 months with pVL ≤50 copies/mL. The third drug in the previous regimen was ritonavir-boosted atazanavir (ATV/r) in 79 (28%), and another ritonavir-boosted protease inhibitor (PI/r) in 29 (10%). Ninety (32%) had previously failed with a PI. Proportions of people with virological success at 48/96/144 weeks were 90%/87%/88% (TLOVR) and 74%/67%/59% (snapshot analysis), respectively. The rates of VF were 8%/8%/6%. Rates of adverse events leading to study discontinuation were 0.4%/1%/2%. The multivariable adjusted analysis showed an association between VF and nadir CD4+ (hazard ratio [HR] 0.63 [95% confidence interval [CI]: 0.42-0.93] per 100 cells higher), time with pVL ≤50 copies/mL (HR 0.87 [95% CI: 0.79-0.96] per 6 months longer), and previous failure with a PI (HR 2.78 [95% CI: 1.28-6.04]). Resistance selection at failure was uncommon.A switch to ATV + ABC/3TC in selected subjects with suppressed viremia was associated with low rates of VF and discontinuation due to adverse events, even in subjects not receiving ATV/r. The strategy might be considered in those with long-term suppression and no prior PI failure

Sustained expansion of NKT cells and antigen-specific T cells after injection of α-galactosyl-ceramide loaded mature dendritic cells in cancer patients

Natural killer T (NKT) cells are distinct glycolipid reactive innate lymphocytes that are implicated in the resistance to pathogens and tumors. Earlier attempts to mobilize NKT cells, specifically, in vivo in humans met with limited success. Here, we evaluated intravenous injection of monocyte-derived mature DCs that were loaded with a synthetic NKT cell ligand, α-galactosyl-ceramide (α-GalCer; KRN-7000) in five patients who had advanced cancer. Injection of α-GalCer–pulsed, but not unpulsed, dendritic cells (DCs) led to >100-fold expansion of several subsets of NKT cells in all patients; these could be detected for up to 6 mo after vaccination. NKT activation was associated with an increase in serum levels of interleukin-12 p40 and IFN-γ inducible protein-10. In addition, there was an increase in memory CD8(+) T cells specific for cytomegalovirus in vivo in response to α-GalCer–loaded DCs, but not unpulsed DCs. These data demonstrate the feasibility of sustained expansion of NKT cells in vivo in humans, including patients who have advanced cancer, and suggest that NKT activation might help to boost adaptive T cell immunity in vivo