(401bm) BN-Carbon-Membrane as a Novel/Alternative Separator for Li-Sulfur Batteries with Excellent Performance

Lithium-sulfur (Li-S) batteries have gained considerable attention as next-generation batteries because of their high theoretical capacity of 1672 mAh g-1, lower environmental impact, and reduced cost. However, several critical limitations produce poor electrochemical performance of Li-S batteries, especially those associated with polysulfide shuttling effect.

The introduction of a carbon-modified separator has been tested in order to alleviate these systemic challenges. However, this approach was focused on the suppression of dissolved polysulfides only in the cathodic side, i.e. without considering additional entrapment of polysulfides in the anodic side. Herein, we first constructed a multifunctional tri-layer membrane constituted by a carbon layer and a boron nitride (BN) layer, in order to improve the electrochemical performances of Li-S batteries and protect a Li anode from undesired side-reactions. The use of BN-Carbon-separator, the sulfur cathode exhibited stable capacity over 250 cycles and an exceptional specific capacity (702 mAh g-1) at a high current density of 4 C. Moreover, the BN-Carbon-separator presented a synergic effect on the uniform plating/stripping of Li and thus restraining critical dendritic lithium growth on the anode; this derived in a considerably stable operation of Li anode with high Coulombic efficiency and enhanced cycling performance.