Integrating Polar and Conductive Fe₂O₃–Fe₃C Interface with Rapid Polysulfide Diffusion and Conversion for High-Performance Lithium–Sulfur Batteries

Abstract

A low-cost in situ formed Fe 2 O 3 −Fe 3 C heterostructure highly dispersed in carbon nanofiber was delicately designed via a facile one-pot electrospinning method. The intense anchoring (by Fe 2 O 3 ) and rapid electron transfer (by Fe 3 C) for lithium polysulfides transformation can be simultaneously achieved on the Fe 2 O 3 −Fe 3 C heterostructure interface, thus preventing the amassment of lithium polysulfides benefiting from its excellent interfacial contact and improving sulfur utilization. Experimental characterizations and DFT calculations confirmed the restrained polysulfides shuttle and enhanced redox kinetics. Therefore, the battery containing optimal Fe 2 O 3 −Fe 3 C heterostructure delivered a high capacity of 776.2 mA h g −1 after 300 cycles at 1 C at a low fading rate of 0.037% per cycle. Even at a high sulfur loading of 3.5 and 4.5 mg cm −2 , high capacities of 773.6 and 533.6 mA h g −1 at 0.5 C can be achieved with capacity retentions of 91.7 and 94.2%, respectively. This distinctive heterostructure proposes an effective design of high-performance lithium−sulfur batteries contributing to the excellent electrochemical performance, which can synergize the virtues of effectively adsorptive metal oxides and appealing conductive metal carbides.

Synergistics of Fe3C and Fe on Mesoporous Fe–N–C Sulfur Host for Nearly Complete and Fast Lithium Polysulfide Conversion

“…The comparison also suggests the better performance of the Fe 3 C@FeNC host compared with the Fe@FeNC host, implying a stronger adsorption capability of the polar Fe 3 C particles. 28 In comparison, the acid-leached FeNC host without any Fe 3 C and Fe exhibited an inferior ability to adsorb polysulfide, probably due to limited active site densities.…”

“…The Fe 3 C/Fe@FeNC host provided the highest sulfur discharge capacity for stage III and reached 980 mAh g −1 , which is higher than the 950 mAh g −1 for sulfur in the Fe 3 C@FeNC host and is also higher than the results described in the literature. 25,[28][29][30]50 In contrast, although sulfur in the Fe@FeNC host delivered a much lower capacity of 905 mAh g −1 for stage III, it exhibited outstanding kinetics as seen in the similar discharge plateau voltage of sulfur in the Fe 3 C/Fe@ FeNC host. Overall, this comparison reveals that Fe 3 C enabled a higher discharge capacity for stage III, presumably due to its stronger polysulfide adsorption capability (Figure 3), whereas Fe enabled better kinetics for catalyzing the short-chain polysulfide conversion to solid Li 2 S. The synergy of Fe 3 C and Fe in the Fe 3 C/Fe@FeNC host provided the highest capacity and best redox kinetics.…”

Lithium–Sulfur Battery Cathode Design: Tailoring Metal‐Based Nanostructures for Robust Polysulfide Adsorption and Catalytic Conversion

“…The novel interlayer design resulted in a high capacity of 776.6 mAh g −1 at 0.5 C with a high sulfur loading of 4.5 mg cm −2 . [319] As research on the development of hybrid metal-based compounds for Li-S batteries is driving a global boom, it is anticipated that novel adsorbent and catalytic nanomaterials with tunable morphologies can become a potential frontrunner candidate to aim for a strong affinity and fast conversion of LiPS in the pursuit of inhibiting shuttle effect in high-energy-density Li-S batteries with excellent cycling stability.…”

Recent advance on Co‐based materials for polysulfide catalysis toward promoted lithium‐sulfur batteries

“…[ 10 ] These heterostructures combine the merits of the two building blocks and achieve smooth trapping‐diffusion‐conversion of LiPSs across the interface. [ 13 ] Benefitting from these advantages, Pan and co‐workers employed graphene decorated with hetero‐Co 9 S 8 ‐NiS sheets (BMS‐G) as a host material to support S in cathodes, delivering excellent cycling stability only 0.031% capacity fading per cycle. [ 115 ]…”

“…[ 8 ] Typically, porous or hollow carbonaceous materials were widely used to physically confine LiPSs, [ 1 ] but their non‐polar surfaces fail to effectively anchor LiPSs to suppress shuttle effect on account of the weak van der Waals forces between carbon materials and LiPSs. [ 9 ] In view of this, polar transition metal compounds such as metal oxides, [ 10 ] sulfides, [ 11 ] and nitrides [ 12 ] have been developed to take advantages of their stronger chemical interactions with LiPS efficiently alleviating the dissolution of LiPSs in electrolytes, [ 13 ] showing considerable capability for stabilizing the sulfur electrochemistry and enhancing sulfur utilization.…”