Regulating Fe Aggregation State via Unique FeNV Pre‐Coordination to Optimize the Adsorption‐Catalysis Effect in High‐Performance Lithium‐Sulfur Batteries

Abstract

Lithium‐sulfur batteries (LSBs) suffer from uncontrollable shuttling behavior of lithium polysulfides (LiPSs: Li2Sx, 4 ≤ x ≤8) and the sluggish reaction kinetics of bidirectional liquid‐solid transformations, which are commonly coped through a comprehensive adsorption‐catalysis strategy. Herein, a unique FeNV pre‐coordination is introduced to regulate the content of “dissociative Fe3+” in liquid phase, realizing the successful construction of N‐doped micro‐mesoporous “urchin‐like” hollow carbon nanospheres decorated with single atom Fe‐N4 sites and VN nanoparticles (denoted as SA‐Fe/VN@NMC). The strong chemisorption ability toward LiPSs and catalyzed Li2S decomposition behavior on VN, along with the boosted reaction kinetics for sulfur reduction on SA‐Fe sites are experimentally and theoretically evidenced. Moreover, the nanoscale‐neighborhood distribution of VN and SA‐Fe active sites presents synergistic effect for the anchoring‐reduction‐decomposition process of sulfur species. Thus SA‐Fe/VN@NMC presents an optimized adsorption‐catalysis effect for the whole sulfur conversion. Therefore, the SA‐Fe/VN@NMC based Li‐S cells exhibit high cyclic stability (a low decay of 0.024% per cycle over 700 cycles at 1 C, sulfur content: 70 wt%) and considerable rate performance (683.2 mAh g−1 at 4 C). Besides, a high areal capacity of 5.06 mAh cm−2 is retained after 100 cycles under the high sulfur loading of 5.6 mg cm−2. This work provides a new perspective to design the integrated electrocatalysts comprising hetero‐formed bimetals in LSBs.

Amorphous/crystalline RhFeP metallene for hydrazine-assisted water splitting

“…The negative shift of XPS peaks can cause an upshift of the d-band center of Rh, and thus optimize the adsorption of active hydrogen on the catalyst, leading to improved catalytic activity [35,39]. In the XPS spectrum of Fe 2p, two peaks at 723.90 and 711.00 eV are attributed to Fe 2+ , and two peaks at 728.40 and 715.50 eV are attributed to Fe 3+ (figure 2(c)) [40,41]. Furthermore, two peaks of P 2p spectrum at 133.30 and 131.30 eV can be attributed to P 5+ and P°, respectively (figure 2(d)) [42,43].…”

Vanadium as Auxiliary for Fe–V Dual-Atom Electrocatalyst in Lithium–Sulfur Batteries: “3D in 2D” Morphology Inducer and Coordination Structure Regulator

“…10,11 Second, the sluggish reaction kinetics between soluble LiPSs and solidphase Li 2 S 2 /Li 2 S leads to the accumulation of polysulfides in electrolytes and irregular precipitation of Li 2 S during the discharging process, finally exacerbating the shuttle effect and limiting the activation of Li 2 S in the charging process. To deal with the aforementioned problems, significant efforts have been devoted to explore electrocatalysts that could chemically anchor LiPSs or accelerate the sulfur conversion especially between LiPSs and Li 2 S, such as well-designed nanostructured metal particles, 13 metal oxides, 14,15 metal sulfides, 16,17 metal carbides, 18,19 metal nitrides, 20 and singleatom metal catalysts (SAMCs). 1,21 However, when serving as a sulfur host in a cathode, the active sites of these electrocatalysts may be shadowed by "dead sulfur", resulting in a deficiency of activity; besides, the cathode "inside" modification cannot prominently prevent the diffusion of LiPSs through the PP separator.…”

“…To deal with the aforementioned problems, significant efforts have been devoted to explore electrocatalysts that could chemically anchor LiPSs or accelerate the sulfur conversion especially between LiPSs and Li 2 S, such as well-designed nanostructured metal particles, metal oxides, , metal sulfides, , metal carbides, , metal nitrides, and single-atom metal catalysts (SAMCs). , However, when serving as a sulfur host in a cathode, the active sites of these electrocatalysts may be shadowed by “dead sulfur”, resulting in a deficiency of activity; besides, the cathode “inside” modification cannot prominently prevent the diffusion of LiPSs through the PP separator . Thus, the cathode “outside” design strategy, that is, a PP separator coating layer, independent interlayer, or electrolyte modulation may be more effective to restrain the shuttling behavior .…”

Design of WO2.83-WN Heterostructure Bidirectional Catalyst for High-Performance Lithium–Sulfur Batteries

“…3 Recently, integrating efficient catalysts into the cathode to expedite the conversion of LiPSs into insoluble products has been deemed one of the most promising approaches to inhibit the "shuttle effect". 4 For efficient conversion of LiPSs, the catalysts must possess a strong adsorption capacity for LiPSs, 5 excellent electron transfer conductivity, and robust catalytic activity to boost conversion kinetics. However, it is challenging to incorporate all these attributes into a single catalyst.…”

“…For efficient conversion of LiPSs, the catalysts must possess a strong adsorption capacity for LiPSs, excellent electron transfer conductivity, and robust catalytic activity to boost conversion kinetics. However, it is challenging to incorporate all these attributes into a single catalyst.…”