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Lithium-sulfur batteries (LSBs) have been recognized as one of the most hopeful new energy storage devices. However, the shuttle effect of polysulfides seriously affects the commercial use of LSBs. In order to alleviate the shuttle effect, in this paper, A novel MoC/N-C composite was firstly prepared by calcining Mo doped ZIF-8 precursor in a nitrogen environment, and then the as prepared MoC/N-C composite was coated on the surface of the commercial polypropylene separator to act as a block layer of lithium polysulfides. The N-C derived from ZIF-8 under high-temperature carbonization can provide good electrical conductivity and block the diffusion of polysulfides by physical adsorption. At the same time, MoC will provide abundant chemisorption sites to effectively hinder the shuttle of polysulfides and promote their redox reactions. Because of the adsorption and catalytic function of MoC/N-C composite, the LSB battery show excellent electrochemical properties even at a high sulfur loading. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries (LSBs) are of great interest to researchers due to their high theoretical specific capacity and high energy density. Unfortunately, because of sulfur's weak conductivity and the shuttle effect of polysulfides, the application prospects of LSBs are facing great challenges. To suppress the shuttle effect of polysulfides, nanorod-like CeO 2 and CeO 2 -C using Ce-MOF as the precursor was successfully prepared and applied to the separator of LSBs. Coating CeO 2 and CeO 2 -C obtained by calcination in different atmospheres on PE separators can effectively enhance the electrochemical properties of LSBs due to the excellent chemisorption and catalytic effect of CeO 2 on lithium polysulfides. In particular, CeO 2 -C which is obtained by calcination of Ce-MOF in N 2 atmosphere has abundant micro and meso porous structures, which can quickly adsorb polysulfide in the electrolyte and accelerate the redox kinetics at the same time. Moreover, the nano-rod structure of CeO 2 and CeO 2 -C also improves the conductivity of the separator. After a series of electrochemical tests, it was discovered that the discharge capacity of the CeO 2 -C coated separator battery on the first cycle was 1240 mA h g−1 when the cathode sulfur loading was approximately 2.5 mg cm−2, and that the discharge capacity remained 520 mA h g−1after 500 loops at 0.5 C. Even when the sulfur loading reaches 5.5 mg cm−2, it also has a good cyclic stability, demonstrating its application potential. Nanorod-like CeO 2 and CeO 2 -C were synthesized using Ce-MOF as precursor under different atmospheres, and successfully applied to the separator of LSBs. CeO 2 -C has excellent adsorption and catalytic ability due to its large specific surface area and dispersed active centers, and the conductivity of CeO 2 is improved after carbonization. Therefore, the modified LSBs have excellent electrochemical performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Due to the increasing demand of new energy vehicles and large-scale power grids for high energy density devices, lithium-sulfur batteries (LSBs) have attracted more and more researchers' attention stemming from their advantages of high theoretical specific capacity, low cost of active substances and environmental friendliness. However, there are still some intractable problems hindering the commercialization of LSBs, among which the most serious problem is "shuttle effect" of polysulfides. For the purpose of solving this problem, this paper prepared hollow structure molybdenum sulfide/cobalt sulfide mixed with amorphous carbon (MoS 2 /Co 9 S 8 /C) (HMCC) nanoparticles using ZIF-67 as the precursor and coated on the side of ordinary PE separator facing the positive electrode by a simple scraper coating process. The combination of MoS 2 and Co 9 S 8 bimetallic sulfides can not only adsorb and catalyze the rapid transformation of intermediates, but also effectively conduct lithium ions mainly because of the exposure of many active sites of layered MoS 2 in the outermost layer. In addition, a small amount of carbon inside can enhance electrical conductivity of the coating, increasing the utilization of active substances, and the stable hollow structure can act as a "transfer station", greatly inhibiting the large amount of polysulfides to run off. The dual advantages of structure and composition make the modified separator have excellent performance in different current densities. Reversible specific capacities of 930.4 mAh g−1 and 690.7 mAh g−1 are released at 0.5 C and 1 C, and capacity retention of 72 % and 64 % after 500 and 600 cycles, respectively. In addition, due to the rapid conduction of lithium ions, the growth of lithium dendrites is greatly inhibited, which maintains the high safety of the battery. This provides a new research direction for the application of other new bimetallic sulfides in the separator modification of LSBs. • A hollow bimetallic sulfide composite MoS 2 /Co 9 S 8 /C is derived from ZIF-67. • MoS 2 /Co 9 S 8 /C is used as a separator coating layer for lithium polysulfides. • The hollow MoS 2 /Co 9 S 8 /C show both physical confinement and catalytic effect on lithium polysulfides. [ABSTRACT FROM AUTHOR]