Preparation and performance of a novel core-shell Gel Polymer Electrolytes
A novel core-shell latex Gel Polymer Electrolytes (GPE) based on poly (methyl methacrylate-acrylonitrile -styrene) (P(MMA-AN-ST)) was prepared for applications in Li-ion batteries. The structure and the performance of the polymer and the GPE were characterized with FTIR, DSC/TG, TEM, SEM, LSV and CA. It is shown that the copolymer has a high thermal stability up to 320°C and the porous structure of the membrane was formed effectively. As-prepared gel polymer electrolytes exhibits a high ionic conductivity of 3.52×10−3 Scm−1 at 25°C and it is electrochemically stable up to 5.2V (vs. Li). This novel GPE can be potentially applied to the manufacture of PLBs.
Polymer Electrolyte from Natural Rubber-Polyacrylic Acid and Polypyrrole and Its Application
A polymer host was prepared by admicellar polymerization of acrylic acid (AA) monomer coated on natural rubber (NR) to form a core-shell material (PAA-adp-NR). To form a polymer electrolyte, the electrical properties, including ionic conductivity and photovoltaic property, were measured to study the potential for use in the dye sensitized solar cells (DSSCs). PAA-adp-NR having the highest shell content (62%) showed the maximum ionic conductivity and energy conversion efficiency (η) at 1.86 mS cm-1 and 1.80%, respectively. The crosslinked structure of 62PAA-adp-NR provided η up to 1.99% (AA:N-methylene bisacrylamide (NMBA) at 500:1 mole ratio) and enhanced a long-term material stability. After oxidative polymerization with polypyrrole (PPy) on 62PAA-adp-NR, the conductivity increased up to 2.43 mS cm-1. In the case of crosslinked PAA-adp-NR/PPy, the conductivity and η showed the highest value at 5.48 mS cm-1 (AA:NMBA at 100:1 mole ratio) and 2.38% (AA:NMBA at 500:1 mole ratio), respectively.
ROOM- AND HIGH-TEMPERATURE MAGNETIC PROPERTIES OF Sm(CobalFexCu0.088Zr0.025)7.5 (x=0.30) SINTERED MAGNETS
The effect of Fe content on room- and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x=0-0.30) sintered magnets, prepared by the conventional powder metallurgy method, has been systematically studied. With increasing Fe content, the remanences BT and maximum energy products (BH)max at room temperature gradually increase and reach optimal values of 1.055 T with x=0.27 for BT, and 205 kJ/m3 with x=0.21 for (BH)max, respectively, and then drop sharply with further Fe increase. An excessive addition of Fe (x≥0.24) results in rapid deterioration of permanent magnetic properties due to the formation of a considerable amount of FeCo soft magnetic phase. It was found that the effect of Fe content on high temperature stability is huge. The lower the Fe content, the smaller the temperature coefficient of coercivity. When x=0.07, a temperature coefficient of coercivity of -0.14%/K (293-723 K) can be achieved, as compared with -0.23%/K for x=0.21. BT of 0.725 T, bHc of 517 kA/m, iHc of 764 kA/m, and (BH)max of 95 kJ/m3 at 723 K were obtained, and the B-H demagnetization curve remains a straight line.