Inorganic separators enable significantly suppressed polysulfide shuttling in high-performance lithium–sulfur batteries

Abstract

Despite being a promising energy storage system due to their high theoretical energy density of 2567 W h kg⁻¹ and economic applicability, liquid electrolyte based lithium–sulfur (Li–S) batteries suffer from several challenges including the polysulfide shuttling effect and lithium dendrite growth, causing continuous capacity decay and severe safety concerns. To address these issues, three types of porous ceramic membranes (garnet type Li_6.4La₃Zr_1.4Ta_0.6O₁₂, Y_0.16Zr_0.84O_2−δ, and Al₂O₃) are presented as separators for Li–S batteries. It is found that the mechanically stiff separators not only have strong affinity for polysulfides but also have high mechanical strength to block lithium dendrite penetration, resulting in a significantly improved electrochemical performance and dramatically enhanced safety of Li–S batteries. Specifically, by employing the Li_6.4La₃Zr_1.4Ta_0.6O₁₂ separator, the Li–S battery can achieve an extended cycle life (over 500 cycles at 0.5C with a capacity decay of 0.034% per cycle on average) and high rate performance up to 2C, outperforming the reported Li–S batteries based on dense ceramic membranes. This work has valuable reference significance in developing porous inorganic separators and inorganic/organic composite electrolytes for high-performance Li–S batteries with enhanced safety characteristics.