Mo and Ni Coordinated Bimetallic Oxide as Catalyst in Modified Separators for Low-Capacity Decay Lithium Sulfur Batteries

Graphical The NiMoO 4 -modified separator can not only use its own strong polarity to chemisorption of polysulfides and effectively suppress the shuttle effect, but also can promote the mutual transformation between polysulfides of different phases, reduces the reaction potential barrier, and the redox kinetics is significantly improved. Besides, the hollow microsphere structure facilitates the penetration of electrolyte and establishes a pathway for ion/electron transport, which accelerates the Li + diffusion rate. Lithium-sulfur (Li−S) batteries are considered to be the most promising candidates for achieving low-cost, high-energy density systems. The serious shuttle effect of polysulfides (LiPS) and the sluggish redox kinetics have become major obstacles to the practical application of Li−S batteries. Herein, a hollow microsphere structure of transition bimetallic oxide nickel molybdate (NiMoO 4 ) was prepared by hydrothermal reaction and calcination method. It was used as a separator coating material to inhibit LiPS shuttle and promote efficient redox conversion of sulfur species. The hollow microsphere structure not only possesses a large internal space to physically confine LiPS but also exposes abundant active sites to enhance the redox kinetics of LiPS. The NiMoO 4 shows superior adsorption ability for LiPS and accelerated ion/electron transport rates compared to NiO, thus facilitating the anchoring-conversion-diffusion processes of polysulfides. Benefiting from this versatility, the Li−S batteries with NiMoO 4 -PP exhibit a high discharge specific capacity of 1354.5 mAh g −1 at 0.1 C. In addition, the battery exhibits excellent cycling stability with a capacity decay rate of 0.027% for 500 cycles at 2 C. These results demonstrate the potential application of NiMoO 4 -based electrocatalysts in high-performance Li−S batteries.