Wide-Temperature-Range Li–S Batteries Enabled by Thiodimolybdate [Mo₂S₁₂]^2– as a Dual-Function Molecular Catalyst for Polysulfide Redox and Lithium Intercalation

Abstract

In lithium−sulfur batteries, a serious obstacle is the dissolution and diffusion of long-chain polysulfides, resulting in rapid capacity decay and low Coulombic efficiency. At present, a common practice is designing cathode materials to solve this problem, but this gives rise to reduced gravimetric and volumetric energy densities. Herein, we present a thiodimolybdate [Mo 2 S 12 ] 2− cluster as sulfur host material that can effectively confine the shuttling of polysulfides and contribute its own capacity in Li−S cells. Moreover, the [Mo 2 S 12 ] 2− cluster as a "bidirectional catalyst" can effectively catalyze polysulfide reduction and lithium sulfide oxidation. We further investigate the catalytic mechanism of [Mo 2 S 12 ] 2− clusters by theoretical calculations, in situ spectroscopic techniques, and electrochemical studies. The (NH 4 ) 2 Mo 2 S 12 /S cathodes show good electrochemical performance under a wide range of temperatures. In addition, a pouch cell fabricated with (NH 4 ) 2 Mo 2 S 12 /S cathodes maintains a stable output for more than 50 cycles.

Core–shell polyoxometalate-based zeolite imidazole framework-derived multi-interfacial MoSe2/CoSe2@NC enabling multi-functional polysulfide anchoring and conversion in lithium–sulfur batteries

“…Secondly, a new pair of peaks belonging to S B 0 appears after complete contact with Li 2 S. All of these changes in the S 2p spectrum point to the same information, namely, the oxidation of insoluble Li 2 S to soluble sulfides in the presence of MoSe 2 /CoSe 2 @NC. 51 To summarize these results, it can be found that Li 2 S is mainly oxidized by MoSe 2 in MoSe 2 /CoSe 2 @NC, which is in line with the conclusion of the above adsorption experiment. Finally, the Li 1s spectrum of the MoSe 2 /CoSe 2 @NC + Li 2 S sample is exhibited in Fig.…”

“…3g). There are two new peaks appearing at 417 and 480 nm in the UV-vis spectrum of MoSe 2 /CoSe 2 @NC + Li 2 S, corresponding to S 4 51 To summarize these results, it can be found that Li 2 S is mainly oxidized by MoSe 2 in MoSe 2 / CoSe 2 @NC, which is in line with the conclusion of the above adsorption experiment. Finally, the Li 1s spectrum of the MoSe 2 /CoSe 2 @NC + Li 2 S sample is exhibited in Fig.…”

Dynamic evolution of electrocatalytic materials for Li–S batteries

“…112 In Li-S batteries, Ma et al discovered a symmetric binuclear molybdenum complex [Mo 2 S 12 ] 2À as a bidirectional electrocatalyst. 113 In the discharge process, [Mo 2 S 12 ] 2À clusters exhibit a dynamic Li-ion intercalation process similar to Mo 6 S 8 and evolve into Li 8 (Mo 2 S 12 ), which can enhance LiPS adsorption (Fig. 5a) and accelerate Li-ion migration.…”

Boosted Polysulfide Conversion by Co, Mn Bimetallic-Modulated Nitrogen–Carbon Material for Advanced Lithium–Sulfur Batteries

“…Therefore, the researchers introduced nitrogen-doped carbon (N–C) with abundant pyrroline nitrogen and pyridine nitrogen structures to adsorb LiPSs Unfortunately, due to the low doping rate of heteroatoms, it is still difficult to overcome the serious capacity fading problem. So, the researchers introduced polar compounds (metal oxides, , nitrides, , sulfides, , etc.) that can form a certain chemical adsorption with polysulfides via the soft acid–soft base interaction between transition-metal cations and S 2– /S 2 2– , making them excellent chemisorption sites .…”