Influence of operating temperature on the activation efficiency of Li-ion cells with xLi2MnO3-(1-x)LiMn0.5Ni0.5O2 electrodes

In this study, the effect of operating temperature at 55 °C on xLi2MnO3-(1-x)LiMn0.5Ni0.5O2 electrodes during the charge/discharge process at different current densities was investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for structural and morphological analysis of the fabricated cathode materials, while charge-discharge curves and differential capacity were used to study the electrochemical behavior. Results confirm the formation of the structures with two phases associated with the components of the layered material. It was found that at 55 °C, a capacity higher than 357 mAh g-1 could be achieved at a voltage of 2.5-4.8 V vs. Li/Li+, which was larger than the capacity achieved at room temperature. At 55 °C, a change in valence could be observed during charging and discharging due to the change in the position of the peaks associated with Mn and Ni, highlighting cathodic material with x = 0.5 as the material that retains the layered structure at this temperature. This work confirms the good performance of electrodes made with this material at elevated temperatures and gives a better understanding of its electrochemical behavior

Effect of x on the Electrochemical Performance of Two-Layered Cathode Materials xLi2MnO3–(1−x)LiNi0.5Mn0.5O2

In our study, the cathodic material xLi2MnO3–(1−x)LiNi0.5Mn0.5O2 was synthesized by means of the co-precipitation technique. The effect of x (proportion of components Li2MnO3 and LiNi0.5Mn0.5O2) on the structural, morphological, and electrochemical performance of the material was evaluated. Materials were structurally characterized using X-ray diffraction (XRD), and the morphological analysis was performed using the scanning electron microscopy (SEM) technique, while charge–discharge curves and differential capacity and impedance spectroscopy (EIS) were used to study the electrochemical behavior. The results confirm the formation of the structures with two phases corresponding to the rhombohedral space group R3m and the monoclinic space group C2/m, which was associated to the components of the layered material. Very dense agglomerations of particles between 10 and 20 µm were also observed. In addition, the increase in the proportion of the LiNi0.5Mn0.5O2 component affected the initial irreversible capacity and the Li2MnO3 layer’s activation and cycling performance, suggesting an optimal chemical ratio of the material’s component layers to ensure high energy density and long-term durability

ZnO nanoparticles obtained by green synthesis as an alternative to improve the germination characteristics of L. esculentum

Tomatoisanimportantcropduetoitsnutritionalcontributionsandorganolepticproperties, which make it an appetizing vegetable around the world. In its sowing, the use of seed is the most accessible propagation mechanism for farmers. However, the induction to germination and emergence is often limited in the absence of stimulants that promote the development and growth of the seedling, added to the interference of infectious agents that notoriously reduce the vitality and viability of the seed. Given this, it was proposed as a research objective to determine the effect of zinc oxide nanoparticles (ZnO NPs) mediated by a green route on the germinative characteristics of Lycopersicon esculentum Mill. 1768 “tomato”. The experimental phase consisted of the synthesis of ZnO NPs and its subsequent characterization. After its synthesis, its inoculation was conducted during the germination of seeds of L. esculentum, considering six sample groups for the treatment with zinc nanoparticles (T1: Control; T2: 21.31 ppm; T3: 33.58 ppm; T4: 49.15 ppm; T5: 63.59 and T6: 99.076 ppm). The results indicate that concentrations close to 100 ppm of ZnO NPs are ideal in the treatment of L. esculentum seeds, due to the promotion of enzymatic and metabolic activity to achieve cell elongation; likewise, the biosynthesized nanoparticles showed no phytotoxicity, due to the fact that, in all the treatments, there were processes of germination and emergence. This was linked to the generation of a Zn0-phenolate complex through a chelating effect, which generates compatibilitywiththeseedand,comparedtoclassicinorganicsynthesis,usuallyshowsphytotoxicity. In this sense, green synthesis is presented as a great alternative in this type of application

Influencia de la ferrita de cobalto en la propiedades magnetoeléctricas de las películas delgadas de ferrita de bismuto depositadas por spin coating

Las películas de (1-x) BiFeO3- (x) CoFe2O4 variando la concentración (x = 0, 0.1, 0.2 y 0.3), fueron depositadas por spin coating sobre sustratos de Pt (Pt/TiO2/SiO2/Si) a partir de soluciones precursoras con una concentración de 0.05 molar, la cual fue obtenida por sol-gel. En la caracterización de las películas delgadas se estudió la estructura y las propiedades magnetoeléctricas mediante difracción de rayos X, corriente de fuga, constante dieléctrica, curva de histéresis ferroeléctrica y ferromagnética. En el difractograma de rayos X se muestran picos característicos con la formación de BiFeO3 y el crecimiento de los picos pertenecientes al CoFe2O4 con el aumento de x. Todas las muestras revelan poca corriente de fuga, siendo la menor de 10-10 A / cm2 para (0.8) BiFeO3- (0.2) CoFe2O4.  La constante dieléctrica se incrementó en el rango de 102Hz a 105Hz luego disminuyó debido a la relajación dieléctrica, para todas las muestras la pérdida dieléctrica es menor al 4%. Todas las películas muestran polarización y magnetización remanentes mayores a 60 μC/cm2 y 30 emu/gr  respectivamente.  Palabras clave: magnetoeléctricas, películas, ferromagnética  y ferroeléctrica