Enhanced Multiferroic Properties of YMnO3 Ceramics Fabricated by Spark Plasma Sintering Along with Low-Temperature Solid-State Reaction

Based on precursor powders with a size of 200–300 nm prepared by the low-temperature solid-state reaction method, phase-pure YMnO3 ceramics are fabricated using spark plasma sintering (SPS). X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that the high-purity YMnO3 ceramics can be prepared by SPS at 1000 °C for 5 minutes with annealing at 800 °C for 2 h. The relative density of the sample is as high as 97%, which is much higher than those of the samples sintered by other methods. The present dielectric and magnetic properties are much better than those of the samples fabricated by conventional methods and SPS with ball-milling precursors, and the ferroelectric loops at room temperature can be detected. These findings indicate that the YMnO3 ceramics prepared by the low temperature solid reaction method and SPS possess excellent dielectric lossy ferroelectric properties at room temperature, and magnetic properties at low temperature (10 K), making them suitable for potential multiferroic applications

Hybrid gel polymer electrolyte based on 1-methyl-1-Propylpyrrolidinium Bis(Trifluoromethanesulfonyl) imide for flexible and shape-variant lithium secondary batteries

Lithium ion conducting polymer electrolytes with broad electrochemical stability, good mechanical strength, high thermal stability, and easy processability are necessary for all-solid-state and shape-variant lithium secondary batteries. Hybrid gel polymer electrolytes incorporating an ionic liquid have been attracting attention for application in solid-state lithium secondary batteries owing to their superior thermal properties compared to conventional electrolyte systems. In this study, a variety of polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), lithium bis(trifluoromethanesulfonyl) imide (LiTFSI), and 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PMPyrrTFSI) are prepared, and an in-depth study of their composition dependence and electrical properties is conducted to develop the optimum composition. The composition dependent ionic conductivity of the polymer electrolyte increases with increasing LiTFSI and PMPyrrTFSI and reaches a maximum value of 6.93 × 10−4 S cm−1 at room temperature (25 °C) when the polymer electrolyte contains 30 wt% LiTFSI and 60 wt% PMPyrrTFSI. In addition, the optimized gel polymer electrolytes consisting of PVdF-HFP/LiTFSI/PMPyrrTFSI (70/30/60 by weight, i.e., 70PVdF-HFP/30LiTFSI/60PMPyrrTFSI) look transparent and exhibit high mechanical stability and excellent thermal stability up to 420 °C. Finally, the lithium iron phosphate (LiFePO4)/lithium metal solid-state cells coupled with the optimized gel polymer electrolyte are prepared, and their discharge characteristics are studied. The 70PVdF-HFP/30LiTFSI/60PMPyrrTFSI based solid-state cell delivered a maximum discharge capacity of 151 mAh g−1 at room temperature with a good rate capability and cycling performance. © 2020 Elsevier B.V.1

Improvement of Electrochemical Performance of Lithium-ion Secondary Batteries using Double-Layered Thick Cathode Electrodes

Various steps in the electrode production process, such as slurry mixing, slurry coating, drying, and calendaring, directly affect the quality and, consequently, mechanical properties and electrochemical performance of electrodes. Herein, a new method of slurry coating is developed: Double-coated electrode. Contrary to single-coated electrode, the cathode is prepared by double coating, wherein each coat is of half the total loading mass of the single-coated electrode. Each coat is dried and calendared. It is found that the double-coated electrode possesses more uniform pore distribution and higher electrode density and allows lesser extent of particle segregation than the singlecoated electrode. Consequently, the double-coated electrode exhibits higher adhesion strength (74.7 N m−1) than the single-coated electrode (57.8 N m−1). Moreover, the double-coated electrode exhibits lower electric resistance (0.152 Ω cm−2) than the single-coated electrode (0.177 Ω cm−2). Compared to the single-coated electrode, the double-coated electrode displays higher electrochemical performance by exhibiting better rate capability, especially at higher C rates, and higher long-term cycling performance. Despite its simplicity, the proposed method allows effective electrode preparation by facilitating high electrochemical performance and is applicable for the large-scale production of high-energy-density electrodes.FALS

PHYLOGENETIC STUDY OF THREE LINES CAVIA PORCELLUS (GUINEA PIGS) PERU, ANDINA AND INTI, "EL PRADO" FARM, UNIVERSITY OF THE ARMED FORCES – ESPE IN ECUADOR

Objective: The present study was undertaken to investigate the morphological and to establish molecular relations between three lines of guinea pigs, which are phenotypically selected and form the basis for a molecular marker-assisted breeding program for the species, in the breeding farm of El Prado.Methods: Synthetic variable was used for qualitative and quantitative analysis of the study population. The DNA was extracted, amplified by PCR and then was sequenced the mitochondrial cytochrome-b gene of the lines Peru, Andina and Inti. The extracted sequences were compared with others of Cavia porcellus, and other associated genes, from neighboring countries, deposited in Genbank.Results: Phenotypic analysis was prioritized desirable characteristics for the producer. The synthetic variable generated three groups of individuals. The best group comprises of guinea pig Andina line, two of Peru, and four of Inti. Molecular characterization showed that the specimens under study achieved an average of 1101.5 bp corresponding to 98.27% of the complete mitochondrial cytochrome-b gene (1120.8bp). On comparison with Genbank sequences we observed a similarity of 98% (identical pairs), and 1.92% of variability (transition and transversion). Site analysis found 85.5% of conserved sites and 14.5% of variable sites, of which 55.48% were parsimony informative.Conclusion: These results suggest that the specimen I5 (Inti) was selected for its qualitative characteristics, good weight of reproductive age and greater intra-population genetic distance. The dendrogram for intraspecific phylogenetic inference of Cavia porcellus was robust, 100% resampling under a frequency analysis of 1000 replicates. These findings not only help in design effective breeding experiments but also help in selecting animals for experiment purposes.Keywords: Cavia porcellus, Cytochrome-b, DNA, Phylogenetic analysi

Synergistic Effect of a Dual-Salt Liquid Electrolyte with a LiNO3 Functional Additive toward Stabilizing Thin-Film Li Metal Electrodes for Li Secondary Batteries

Li metal thickness has been considered a key factor in determining the electrochemical performance of Li metal anodes. The use of thin Li metal anodes is a prerequisite for increasing the energy density of Li secondary batteries intended for emerging large-scale electrical applications, such as electric vehicles and energy storage systems. To utilize thin (20 mu m thick) Li metal anodes in Li metal secondary batteries, we investigated the synergistic effect of a functional additive (Li nitrate, LiNO3) and a dual-salt electrolyte (DSE) system composed of Li bis(fluorosulfonyl)imide (LiTFSI) and Li bis(oxalate)borate (LiBOB). By controlling the amount of LiNO3 in DSE, we found that DSE containing 0.05 M LiNO3 (DSE-0.05 M LiNO3) significantly improved the electrochemical performance of Li metal anodes. DSE-0.05 M LiNO3 increased the cycling performance by 146.3% [under the conditions of a 1C rate (2.0 mA cm(-2)), DSE alone maintained 80% of the initial discharge capacity up to the 205th cycle, whereas DSE-0.05 M LiNO3 maintained 80% up to the 300th cycle] and increased the rate capability by 128.2% compared with DSE alone [the rate capability of DSE-0.05 M LiNO3 = 50.4 mAh g(-1), and DSE = 39.3 mAh g(-1) under 7C rate conditions (14.0 mA cm(-2))]. After analyzing the Li metal surface using scanning electron microscopy and Xray photoelectron spectroscopy, we were able to infer that the stabilized solid electrolyte interphase layer formed by the combination of LiNO3 and the dual salt resulted in a uniform Li deposition during repeated Li plating/stripping processes.FALS