Electrochemical Performance of Hydroxylated Multi-walled Carbon Nanotube Sandwich Separator in Lithium-sulfur Battery

Hydroxylated multi-walled carbon nanotube cellulose paper (MWCNTs-OHP) was obtained by vacuum filtration of hydroxylated multi-walled carbon nanotubes (MWCNTs-OHP) and paper fibers. A multi-functional PP@MWCNTs-OHP@PP sandwich separator was formed by MWCNTs-OHP cellulose paper sandwiching between two polypropylene(PP) membranes and was used in lithium-sulfur battery. The morphology and structure of PP@MWCNTs-OHP@PP were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy and energy dispersive spectroscopy (EDS). The electrochemical test showed that the initial discharge capacity of Li-S batteries with the PP@MWCNTs-OHP@PP sandwich separator reached to 1532 mA . h/g and the utilization rate of active substances reached 91.5%. The capacity still maintained 516 mA . h/g at 1C after 500 cycles with stabilized coulombic efficiency above 96.4% and slow capacity decay rate of 0.028% per cycle. As the charge-discharge rate decreased from 3C to 0.1C, the discharge capacity recovered from 336 mA . h/g to 820 mA . h/g, showing excellent magnification.