Gd-MOF-Derived GdS/C for the Modification of Separators in Lithium–Sulfur Batteries

Abstract

Because of its excellent energy density and specific capacity, lithium–sulfur batteries (LSBs) are considered one of the most promising energy storage devices. However, the shuttle effect and slow transformation of polysulfides hinder their practical application. To address the shuttle effect, we used a Gd-MOF precursor for high-temperature carbonization to obtain GdS@C composite as a modification layer for LSB separators. The strong affinity of metal sulfide to sulfur enhances the chemical anchoring of polysulfides and catalyzes their transformation. By employing GdS@C as the separator modification material, we effectively suppressed the shuttle effect and improved electrochemical performance. Under a sulfur load of 3 mg cm^–2, the initial discharge specific capacity with GdS@C-modified separator was 888.9 mAh g^–1 at 0.5 C; after 500 cycles, it remained at 435.6 mAh g^–1 with a capacity retention rate of 49.0%. With an increased sulfur loading to 5 mg cm^–2, the first cycle discharge specific capacity at 0.1 C reached 908.4 mAh g^–1; after 100 cycles, it was still at 743.9 mAh g^–1 with an impressive retention rate of 81.9%. These results demonstrate that GdS@C composite material significantly enhances the electrochemical performance of LSBs and showcases its broad application potential.