WS₂-TiO₂ Heterostructure Catalyst for Boosting the Polysulfide Adsorption–Conversion in Lithium–Sulfur Batteries

Abstract

The introduction of suitable catalytic hosts is considered as a suitable way to hinder the "shuttling effect" of lithium polysulfides (LPSs) in lithium−sulfur (Li−S) batteries. At present, most catalytic hosts can accelerate the conversion of LPSs, but there are few reports that catalytic hosts accelerate the conversion of solid-phase discharge products (Li 2 S 2 /Li 2 S) into liquid-phase LPSs. Herein, a heterostructure catalyst with flaky WS 2modified TiO 2 hollow spheres (WS 2 -TiO 2 ) is reported, which accelerates the conversion between liquid-phase LPSs and solidphase Li 2 S 2 /Li 2 S. A Li−S battery with S@WS 2 -TiO 2 cathode exhibits an initial discharge specific capacity of 1091.7 mAh g −1 at 0.3C, outstanding rate capability of 378.7mAh g −1 at 10C, and low capacity decay of 0.0753% per cycle over 800 cycles at 1C. Therefore, this work provides a suitable way to construct heterosturcture catalytic hosts to realize the commercial application of Li−S batteries.

Interfacial Engineering of Ru Nanocluster-Modified TiO2 Nanotube-Assisted Regulation of Lithium Polysulfide Reactions

“…The capacity suddenly decreased after ∼600 cycles, which might be due to the deactivation of the Li anode. 16,20 The corresponding capacity loss was only ∼0.015% per cycle, which was lower than most previous TiO 2 -based sulfur-positive reports (Figure S12). 24,48−51 Meanwhile, Figure 5d,e shows the effect of the as-prepared TiO 2 −Ru nanotubes on the cell life under different high sulfur loadings.…”

“…After a short activation, it achieved a cycling capacity of up to 710 mAh g –1 , maintaining a retention rate of 89.4% even after 700 cycles. The capacity suddenly decreased after ∼600 cycles, which might be due to the deactivation of the Li anode. , The corresponding capacity loss was only ∼0.015% per cycle, which was lower than most previous TiO 2 -based sulfur-positive reports (Figure S12). ,− …”

“…Benefiting from the strong interaction between the TiO 2 surface and polysulfides, which is considered a chemical attraction (S–Ti–O), the diffusion of LiPSs was suppressed to a certain extent . Nevertheless, some previous studies suggested that TiO 2 has a limited acceleration effect for multistep polysulfide conversion. − In addition, TiO 2 is a typical semiconductor material with inferior electron conductivity, which is coupled to deteriorate the overall rate performance of TiO 2 -based Li–S batteries.…”

Promoting overall sulfur redox kinetics for Li–S batteries via interfacial synergy in a NiS–NiTe2 heterostructure-modified separator

“…38,39 Overall, heterogeneous structures exhibit strong adsorption capabilities for polysulfides and demonstrate high catalytic activity in the conversion of polysulfides, making Li–S batteries constructed with heterogeneous structure materials typically exhibit outstanding electrochemical performance. Reported combinations of heterogeneous structure materials currently include oxide–oxide, 40,41 oxide–sulfide, 42–44 oxide–nitride, 45,46 sulfide–sulfide, 47,48 sulfide–nitride, 49,50 and other composite material systems.…”