Li-Ion Transfer Mechanism of Gel Polymer Electrolyte with Sole Fluoroethylene Carbonate Solvent.

Although gel polymer electrolytes (GPEs) represent a promising candidate to address the individual limitations of liquid and solid electrolytes, their extensive development is still hindered due to the veiled Li-ion conduction mechanism. Herein, the related mechanism in GPEs is extensively studied by developing an in situ polymerized GPE comprising fluoroethylene carbonate (FEC) solvent and carbonate ester segments (F-GPE). Practically, although with high dielectric constant, FEC fails to effectively transport Li ions when acting as the sole solvent. By sharp contrast, F-GPE demonstrates superior electrochemical performances, and the related Li-ion transfer mechanism is investigated using molecular dynamics simulations and 7 Li/6 Li solid-state nNMR spectroscopy. The polymer segments are extended with the swelling of FEC, then an electron-delocalization interface layer is generated between abundant electron-rich groups of FEC and the polymer ingredients, which works as an electron-rich "Milky Way" and facilitates the rapid transfer of Li ions by lowering the diffusion barrier dramatically, resulting in a high conductivity of 2.47 × 10-4  S cm-1 and a small polarization of about 20 mV for Li//Li symmetric cell after 8000 h. Remarkably, FEC provides high flame-retardancy and makes F-GPE remains stable under ignition and puncture tests.

Zn(II)-PEG 300 globules as soft template for the synthesis of hexagonal ZnO micronuts by the hydrothermal reaction method.

Hexagonal ZnO micronuts (HZMNs) have been successfully synthesized with the assistance of poly(ethylene glycol) (PEG) 300 via a hydrothermal method. The structure and morphology of the HZMNs were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). An individual ZnO micronut is revealed as twinned crystals. Time-dependent investigation shows that the growth of HZMNs involves a dissolution-recrystallization process followed by Ostwald ripening, in which is the first formed solid ZnO particles dissolve and transform to HZMNs with hollow structure. PEG 300 has been found to play a crucial role in the growth of this unique hollow structure. TEM observations show that the PEG chains aggregate to globules in water, which then have interaction with the dissolved zinc species to form the globules in a coiled state under hydrothermal conditions. These Zn(II)-PEG 300 globules act as soft template for the growth of HZMNs, and the possible growth mechanism is proposed. The room-temperature photoluminescence (PL) spectrum shows red emission around 612 nm with a full width at half-maximum (fwhm) only about 13 nm.