Metal Oxide Interlayer for Long-Lived Lithium-Selenium Batteries.

Abstract

A lithium-selenium (Li-Se)-alkali activated carbon hybrid cell with a tungsten oxide interlayer is implemented for the first time. The Se hybrid at a Se loading of 70 % in the full Li-Se cell delivers a large reversible capacity of 625 mA h gSe -1 , in comparison with 505.8 mA h gSe -1 achieved for the pristine Se cell. This clearly shows the advantage of the carbon in improving the capacity of the Li-Se cell. A tungsten oxide interlayer is drop-cast over the battery separator to further circumvent the issues of polyselenide dissolution and shuttle, which cause severe capacity fading. The oxide layer conducts Li ions, as evidenced from the Li-ion diffusion coefficient of 4.2×10-9 cm2 s-1 , and simultaneously blocks the polyselenide crossover, as it is impermeable to polyselenides, thereby reducing the capacity fading with cycling. The outcome of this unique approach is reflected in the reversible capacities of 808 and 510 mA h gSe -1 achieved for the Li-oxide@separator/Se-alkali activated carbon cell before and after 100 cycles, respectively, thus demonstrating that carbon and oxide can efficiently restrict the capacity fading and improve the performances of Li-Se cells.