Single Atom‐Particle Tandem Catalysis Enables Enhanced Desolvation Kinetics for Low‐Temperature Li‐S Batteries

The commercial implementation of lithium-sulfur (Li-S) batteries is plagued by the sluggish kinetics of interfacial Li(solvent)$_x$$^+$ desolvation and successive redox conversions of sulfur species, exhibiting high tandem barriers. Herein, the tandem catalyst consisted of single Fe atom and Fe $_3$ C nanoparticles on porous carbon sheet (SAPTC@PCS) is initially proposed and developed. As illustrated in theoretical simulation, the neighboring Fe$_3$ C further tunes the
electronic density and affects related coordination structure of atomically distributed iron for reinforcing catalytic efficiency. The as-prepared SAPTC@PCS facilitates the dissociation of Li(solvent)$_x$$^+$ to release more isolated Li$^+$ to participate in the subsequent polysulfide redox conversions by decreasing the desolvation/diffusion barriers, as revealed by in-situ Raman, time-of-flight second ion mass spectroscopy, electronic microscope and X-ray
measurements. Consequently, the cell with SAPTC@PCS delivers a high capacity-retention over 1000 cycles and high rate up to 3 C. Impressively, under the practical mass loading of 6 mg cm$^{−2}$ , the cell stabilizes the capacity of 4.59 mAh cm$^{−2}$ after 90 cycles, and a desirable capacity of 804.8 mAh g$^{−1}$ after 100 cycles is achieved even being exposed to low temperature of 0 °C, demonstrating the feasibility of single atom-particle catalysts for tandem catalysis in Li-S batteries.