Retarding the polysulfide shuttle effect in lithium-sulfur batteries : a parametric study of amount of electrolyte, types of separators, and their interactions

A review of various separators (i.e. cellulose-based, Celgard, fiber glass, track-etched polycarbonate, hydrophobic/phillic PVdf, etc.) has been made to examine the effect of the separator choice on the retardation of the polysulfide shuttle effect. Parameters such as porosity, pore size, thickness, tortuosity, and quantity of electrolyte were experimentally and theoretically explored. Additionally, functionalization of the separators with polyelectrolyte and gold coatings was explored to determine if any physio-chemical interactions further reduce the polysulfide shuttle mechanism and increased cycle performance, power density, and energy density. Preliminary results showed that trilayer Celgard, fiber glass (GF), and hydrophobic materials gave positive results. Increased tortuosity, decreased pore size, gold coatings on GF and Celgard, and multi-layer separators yielded positive results of more than 1500 mAh/g_{sulfur} at current densities around C/8 for no more than 75 cycles (i.e. approx. 100 days). Additionally, the ratio of separator/quantity of electrolyte plays an important role in the polysulfide shuttle effect and must be determined precisely to optimize performance.