RESUMEN
The commercial application of lithium-sulfur (Li-S) batteries is limited by the inherent defects of poor conductivity of sulfur and the shuttling effect of polysulfides. To overcome these limitations, a modified layer comprising a porous network PVDF-PMMA skeleton and Ketjen black (KB) carbon nanoparticles was coated on the polyethylene (PE) separator using the phase inversion method. The PVDF-PMMA-KB (PPK) composite layer with a structure abundant in mesopores can effectively limit the shuttling effect of polysulfides via a physical barrier and adsorption. Moreover, the utilization of active substances substantially increased as the KB carbon nanoparticles could provide additional reaction sites for activating inactive polysulfides and depositing lithium sulfide. The electrochemical properties of the Li-S battery were considerably enhanced using the modified separator with a PPK layer, which was reflected in the higher rate capability and longer cycling life. The cell with a modified separator delivered a specific capacity of 723 mA h g-1 at 1 C, and the capacity retention reached 73.3% after 400 cycles with a low decay rate of 0.223% per cycle. This work provides a novel preparation method for a modified layer on the separator and promotes the large-scale application of Li-S batteries.
RESUMEN
Oxygen vacancy dynamic behavior at room temperature in complex oxides was carefully explored by using a combined approach of ion liquid gating technique and resistance measurements. Heterostructures of PrBaCo2O5+δ/Gd2O3-doped CeO2 epitaxial thin films were fabricated on (001) Y2O3-stabilized ZrO2 single crystal substrates for systematically investigating the oxygen redox dynamics. The oxygen dynamic changes as response to the gating voltage and duration were precisely detected by in situ resistance measurements. A reversible and nonvolatile resistive switching dynamics was detected at room temperature under the gating voltage >13.5 V with pulse duration >1 s.