Incorporation of Fe/FeO_<i>x</i> Nanoparticles into Interlinked <i>N</i>-Doped Porous Carbon Nanofiber Networks to Realizing Sequential Catalytic Conversion of Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries (LSBs) with energy density (2600 Wh/kg) much higher than typical Li-ion batteries (150–300 Wh/kg) have received considerable attention. However, the insulation nature of solid sulfur species and the high activation barrier of lithium polysulfides (LiPSs) lead to slow sulfur redox kinetics. By the introduction of catalytic materials, the effective adsorption of LiPSs, and significantly reduced conversion, energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing these challenges. In this work, a multifunctional catalyst consisting of highly dispersed heterostructure Fe–Fe2O3 nanoparticles was synthesized and introduced to the LSB. Experimental and theoretical analyses revealed that the spontaneous interfacial charge redistribution, resulting in moderate polysulfide adsorption, facilitates the transfer of polysulfides and diffusion of electrons at heterogeneous interfaces. This catalyst achieves sequential catalytic processes on polysulfides with different components. Furthermore, the reduced conversion energy barriers enhanced the catalytic activity of Fe/Fe2O3–NG for expediting LiPS conversion. Consequently, the battery exhibited long-term stability for 300 cycles with 0.03% capacity decay per cycle at 5C. This work provides in-depth insight into the fundamental design principles of effective catalysts for LSBs.