Confined selenium within porous carbon nanospheres as cathode for advanced Li-Se batteries

Selenium (Se) is potential as a promising alternative cathode material for high-energy batteries because of its comparable theoretical volumetric capacity density (3240 mAh cm(-3)) to sulfur (3467 mAh cm(-3)) and a much higher electronic conductivity (1 x 10(-3) S m(-1)) than sulfur (5 x 10(-28) S m(-1)). In this work, we developed a novel Se composite confined within porous carbon nanospheres (Se/PCNs) as cathode for advanced Li-Se battery. A Se loading as high as 70.5 wt% is attained in such composite. The Se/PCNs cathode shows high volumetric capacity density of 3150 mAh/cm(3) and excellent rate capability (retains 57% of the theoretical capacity at 20 degrees C). Remarkably, it exhibits impressive cycling stability over 1200 cycles with a capacity decay as low as similar to 0.03% per cycle. The superior overall battery performance can be ascribed to high loading of active material, effective protective film formed on the surface of the active material, and strong adsorbing ability of Se/Li2Sex provided by the micropore-rich carbon structure. (C) 2014 Elsevier Ltd. All rights reserved.