Polyaniline-Coated Cobalt–Iron Oxide Composites Modified Separator for High Performance Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have a supreme theoretical energy density, which makes them a promising candidate for energy storage. However, the persistent challenge of polysulfide dissolution hinders their extensive adoption. In this study, we developed polyaniline-coated cobalt–iron oxide composites (CFOP) to embellish separators for Li–S batteries via a straightforward calcination, followed by an in situ oxidation polymerization technique. Owing to the synergistic impact of bimetallic oxides and PANi coating, the CFOP-modified separator exhibited improved electrical conductivity and polysulfide adsorption capabilities. At 0.1 C, the sulfur cathode with CFOP modified separator showed a high discharge capacity of 1489.4 mAh·g–1. For the electrode with high sulfur loading (>3 mg·cm–2), it delivered an incipient capacity of 810.9 mAh·g–1 and sustained 498.1 mAh·g–1 after long cycles (300 cycles at 0.5 C). In summary, the CFOP-modified separator successfully mitigated polysulfide shuttling, leading to enhanced electrochemical performance. This research offers valuable views into Li–S battery separator modification.