Hypercrosslinked Polymerization Enabled N‐Doped Carbon Confined Fe₂O₃ Facilitating Li Polysulfides Interface Conversion for Li–S Batteries

Abstract

Facilitating phase conversion efficiency of Li polysulfides to Li2S and restraining the dissolution of Li polysulfides are critical for stable lithium–sulfur (Li–S) batteries. Herein, an in situ formed sulfiphilic superfine Fe2O3 nanocrystals confined in lithiophilic N‐doped microporous carbon (Fe2O3/N‐MC) is derived from one‐step hypercrosslinked polymerization. Uniquely, the dual active sites (Fe2O3 and N) in Fe2O3/N‐MC tend to form “FeS, LiO or LiN” bonding, and then synchronically enhancing the chemisorption and interface conversion ability of Li polysulfides. As a result, 80 wt% S is loaded on Fe2O3/N‐MC and the hybrid cathode delivers high mass capacity (730 mA h g‐1) and excellent cycling stability (87.1% capacity retention over 1000 cycles at 5.0 C). Especially, the cathode also exhibits a high reversible areal capacity of 3.69 mA h cm‐2 at a high areal loading (5.1 mg cm‐2) and a lean electrolyte/sulfur (E/S) ratio (7.5 µL mg‐1) over 500 cycles. This work is anticipated to deepen the comprehension of complex Li polysulfides interphase conversion processes and afford new thoughts for designing new host materials.

Regulating the Molecular Interactions in Polymer Binder for High-Performance Lithium–Sulfur Batteries

“…On the contrary, with the PVDF binder, the R 0 and R s increased sharply and cannot return back during cycling as Figure S23 depicted, illustrating the poor LiPS adsorption and redox reaction in the battery with PVDF, due to its longer charge transfer route and higher energy barrier. The Bode plots in Figure c further confirm that the oxidation reaction in the Li–S battery with PNAVS is reversible and stable . The EIS curves of the battery with different binders before cycling and after 100 cycles are exhibited in Figure S24.…”

“…The Bode plots in Figure 6c further confirm that the oxidation reaction in the Li− S battery with PNAVS is reversible and stable. 55 The EIS curves of the battery with different binders before cycling and after 100 cycles are exhibited in Figure S24. As shown, the electrode with PNAVS owns a smaller semicircle than PNAGA and PVDF before cycling, illustrating a small charge transfer resistance.…”

Realizing fast polysulfides conversion within yolk-shelled NiO@HCSs nanoreactor as cathode host for high-performance lithium-sulfur batteries

“…Moreover, the UV-vis spectrum shows that YS NiO@HCSs had a weaker peak for Li 2 S 6 at about 416 nm than HCSs after adsorption, which confirmed YS NiO@HCSs possessed stronger LiPS absorption ability than HCSs. 46,47 To adequately analyze the natural interaction affinity between YS NiO@HCSs and LiPSs, XPS was conducted on the YS NiO@HCSs-Li 2 S 6 composite after the adsorption experiment. As shown in Fig.…”

“…In order to gain a deep understanding of this conclusion, we employed the galvanostatic intermittent titration technique (GITT) to detect D Li + at various lithiation depths. 47 Generally, D Li + could be determined with formula (1).where τ is the relaxation time (s), n m represents the number of moles (mol), V m corresponds to the molar volume of the active materials (cm 3 mol −1 ), S is related to the contact area of the electrode/electrolyte (cm 2 ), Δ E s is the voltage change caused by an impulse, and Δ E t refers to the constant current voltage change during charging (discharging). Fig.…”

A graphene oxide scaffold-encapsulated microcapsule for polysulfide-immobilized long life lithium–sulfur batteries

“…13–16 For example, carbon-based nanomaterials have been widely used in Li–S batteries. 17–19 Their spherical structure and small size are important for improving the tap density; while their high conductivity benefits the transfer of electrons. Moreover, micro–mesopores and voids inside the sulfur hosts are able to increase the loading and accommodate the volume-change, respectively.…”