Nanocrystalline iron phosphide as polysulfide filter and bifunctional catalyst for increasing capacity of lithium sulfur batteries

Abstract

The commercial potential of lithium-sulfur batteries (LSB) is not yet fully achieved due to slow kinetics and polysulfide shuttling affecting capacity and stability. In this study, lithium polysulfide (LiPS) adsorption progression by thermally synthesized nanocrystalline FeP is superior compared to commercial Fe3P and amorphous FexPy. The catalyst mitigates shuttle effect and increases sulfur utilization with superior catalysis of solid short-chain LiPS (Li2Sx, 1 ≤ x ≤ 4) during charging and discharging, making it bifunctional. The LSB with FeP-coated interlayer achieves initial capacity of 1006 mAh g−1 at 0.1C, and better stability, keeping 660 mAh g−1 at 0.5C for 100 cycles compared to catalyst-free LSB. Along with improvements in other components, the catalyst contributes toward the development of lightweight energy storage. © 2025 Elsevier B.V.