Enhanced Polysulfide Conversion and Shuttle Suppression in Lithium-Sulfur Batteries via Fe-Phytate Modified Sulfur Cathode

Abstract

The practical application of lithium-sulfur (Li-S) batteries is severely impeded by poor cycling performance arising from sluggish redox kinetics and the shuttle effect of polysulfides. In this work, novel transition metal phytates are pioneered to functionalize conductive carbon to address these key limitations. Among a series of phytates evaluated, the Fe-Phytate-modified carbon (Fe-PA@CB) demonstrates superior specific capacity and rate performance. The unique molecular-level Fe-PA coating ensures uniform dispersion and increased active site, leveraging optimized adsorption and enhanced catalytic properties. Consequently, the activation energy for polysulfide conversion is significantly reduced, and polarization potential is minimized. The Fe-PA@CB electrode demonstrates significantly improved cycling stability, retaining 61% of the initial capacity after 500 cycles, compared to 40% retention by a conventional carbon-based cathode. This work not only provides a practical solution for enhancing the electrochemical performance of Li-S batteries but also offers valuable insights into material design and mechanistic understanding, paving the way for the development of next-generation energy storage systems.