Investigation of the Mechanism of Metal-organic Frameworks in Prevent-ing Polysulfides Shuttling - From the Perspective of Composition and Structure

The most critical obstacle preventing Lithium-sulfur batteries (LSBs) from practical application is the shut-tle effect. Herein, we present zirconium based Metal Organic Frameworks (MOFs) composite separator which effectively blocks polysulfides from shuttling without hampering the migration of lithium ions due to the sieving effect of MOFs. Moreover, due to the high BET surface area of 1418 m2 g−1 and the chemi-cal interaction with zirconium and oxygen on MOFs, the polysulfides can also be physically and chemi-cally adsorbed on the surface of MOFs , which further blocks polysulfides from shuttling through the in-tergranular channels of MOF particles. In addition, the wettability of the composite separator with the elec-trolyte is enhanced due to the polar functional groups of –COOH, –OH on MOF. The battery with com-posite separator delivers an initial discharge capacity of 1239 mA h g−1 at 0.2 C, 1147.4 mA h g−1 at 0.5C. The reversible capacity is maintained to 964.1 mA h g−1 with an average fading of only 0.08% per cycle at 0.5C. The capacity at 2C rate with composite separator is 955.8 mA h g−1, which is far more than that of the pristine separator of 289.2 mA h g−1.