Fe3O4/FeP hetero-hybrids confer polypropylene separator robust inhibitory effect to the shuttle of soluble lithium polysulfides

Abstract

High energy density (2600 Wh kg−1) and low price of sulfur make lithium-sulfur batteries (LSBs) become one of the most promising cost-effective energy storage systems in the future. However, lithium-sulfur batteries are still subject to the shuttle effect of soluble lithium polysulfides (LPSs). Herein, ferroferric oxide/iron phosphide (Fe3O4/FeP) hetero-hybrids have been developed and applied as a functional layer to modify the polypropylene separator to inhibit the shuttle of soluble LPSs. Meanwhile, Fe3O4/FeP layer can also accelerate the conversion of adsorbed soluble LPSs due to excellent catalytic performance. As a result, LSBs using Fe3O4/FeP-modified PP separators exhibit superior cycling stability and rate performance. At 0.1C and 5C, it can deliver 1399.8 and 382.1 mAh g − 1, respectively. At 2C, its average capacity decay rate is only 0.0093 % during the initial 900 cycles. Together with the desirable mechanical properties, the Fe3O4/FeP-modified PP separator demonstrate a great potential for practical application in LSBs.