A New Finding on the Enhancement of the Ability of Polysulfide Adsorption of V₂O₅ by Doping Tungsten in Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries are considered to be the most commercially promising lithium metal secondary batteries due to their high specific capacity. However, the shuttle effect of lithium polysulfide (LiPS) in the electrolyte seriously hinders the development of lithium–sulfur batteries. W‐doped V2O5 (W‐V2O5) is prepared by a hydrothermal method, which greatly improves the LiPS adsorption ability of V2O5. The W‐V2O5 powder can discolor the LiPS solution in 1 min. Then, W‐V2O5 is combined with a graphene/carbon nanotube composite (G/CNT) with good conductivity to modify the separator. As a result, the W‐V2O5‐G/CNT‐coated separator allows the sulfur cathode to reach a high initial discharge capacity of 1200 mAh g−1 at 0.2 C and a reversible capacity of 815 mAh g−1 after 200 cycles at 0.5 C, and leads to an excellent rate ability (up to 2 C rate) and a high coulombic efficiency of 99.5%. This provides a new direction for designing efficient LiPS catalysts.

Incorporation ZnS quantum dots into carbon nanotubes for high-performance lithium–sulfur batteries

“…Comparatively, the battery with CNT/ZnS/S 85% showed a relative high R s of 1.39 ohm, while R s values for other batteries were so small (<1 ohm) that could be ignored. The negligible R s and sharp-decreased R ct indicated high charge transfer at surface/interface and in the bulk, which is related to the redistribution of sulfur on the surface of the S/CNT frame and some active substances dissolved in the electrolytes [61]. With the discharge/charge cycling, on one hand, sulfur was redoxidized and redistributed on the electrode surface, thus the sulfur aggregation was prevented and the electrical contact was improved which led to rapidly decreased R s ; on the other hand, the electron transport pathways were gradually stabilized in this process, resulting in the significant decrease of R ct .…”

Advanced Separator Materials for Enhanced Electrochemical Performance of Lithium–Sulfur Batteries: Progress and Prospects

“…The adsorption XPS spectroscopy revealed a decrease in the binding energies of Co 2+ and Mo 6+ by 0.77 and 0.13 eV, respectively. Furthermore, in situ XRD analyses demonstrated that the diffraction peak of S8 gradually weakened with the discharge reaction, and S 8 began to be converted to LiPSs and finally to Li 2 S. Gao et al 37 employed a hydrothermal method to prepare tungsten−doped V 2 O 5 (W−V 2 O 5 ), which was then combined with graphene/carbon nanotube composites (G/ CNTs) and coated onto PP separators. The inclusion of tungsten enhances the adsorption capacity of V 2 O 5 , and V 5+ ions facilitate the oxidation of LiPS, resulting in the generation of sulfur oxides and the formation of Li−V−O−S complexes.…”

CoFe2O4@rGO as a Separator Coating for Advanced Lithium–Sulfur Batteries

“…[ 21 ] However, the interaction between nonpolar carbon and polar polysulfides is not sufficient to effectively immobilize polysulfides in the cathode side. [ 22 ] To strengthen the adsorption capacity of polysulfides, polar materials such as metal oxides (CeO 2 [ 23 ] and V 2 O 5 [ 24 ] ) and metal sulfides (ZnS [ 25 ] and MoS 2 [ 26 ] ) have been used to modify the separators. [ 27 ] Beyond that, some multielement metal oxides containing two metal ions and oxygen anions, such as CoMoO 4 , MnFe 2 O 4 , and LiV 3 O 8 , have stronger interactions with polysulfides.…”