Multifunctional interlayer with simultaneously capturing and catalytically converting polysulfides for boosting safety and performance of lithium-sulfur batteries at high-low temperatures

Lithium-sulfur (Li-S) batteries as extremely promising high-density energy storage devices have attracted extensive concern. However, practical applications of Li-S batteries are severely restricted by not only intrinsic polysulfides shuttle resulting from their concentration gradient diffusion and sluggish conversion kinetics but also serious safety issue caused by thermolabile and combustible polymer separators. Herein, it is presented for the first time that a robust and multifunctional separator with urchin-like Co-doped FeOOH microspheres and multiwalled carbon nanotubes (MWCNTs) as an interlayer simultaneously achieves to suppress polysulfides shuttle as well as improves thermotolerance and nonflammability of commercial PP separator. Accordingly, Li-S batteries with modified separator exhibit remarkable performance in a wide range temperatures of -25–100 °C. Typically, under 25 °C, ultrahigh initial capacities of 1441 and 827.29 mA h g−1 at 1 C and 2 C are delivered, and remained capacities of 936 and 663.18 mA h g−1 can be obtained after 500 cycles, respectively. At 0.1 C, the S utilization can reach up to 97%. Significantly, at 1 C, the batteries also deliver an excellent performance with remained capacities of high to 862.3, 608.4 and 420.6 mA h g−1 after 100, 300 and 450 cycles under 75, 0 and -25 °C, respectively. This work provides a new insight for developing stable and safe high-performance Li-S batteries.