Oxygen-incorporated crystalline/amorphous heterophase cobalt vanadium selenide nanoplates with dense interfacial sites for robust lithium-sulfur batteries

The practical applications of lithium-sulfur (Li-S) batteries are severely impeded by the shuttle effect of soluble lithium polysulfides (LiPSs), sluggish redox reaction kinetics, and insulating nature of sulfur and its discharge products (Li2S2/Li2S). Developing sulfur electrocatalysts with high electrocatalytic activity to accelerate the redox kinetics and polysulfide trapping is critical for Li-S batteries but remains a grand challenge. In this contribution, we demonstrate the delicate design and synthesis of oxygen-incorporated heterophase cobalt vanadium selenide nanoplates with dense crystalline/amorphous interfacial sites (denoted as DC/A O-CoVSe NPs) as high-efficiency sulfur electrocatalysts for Li-S batteries. Such DC/A O-CoVSe NPs possess high electronic conductivity and electrocatalytic activity. Besides, the abundant exposed crystalline/amorphous interfacial sites serve as efficient adsorption-catalytic centers to accelerate the conversion kinetics and alleviate the shuttle effect. Moreover, incorporation of oxygen further increases their affinity to LiPSs because of the introduction of more Li-O interactions. Benefiting from the multifarious advantages, Li-S batteries with DC/A O-CoVSe NP modified separators exhibit high discharge capacity (1400.1 mA h g-1 at 0.1C), excellent rate capability (683.8 mA h g-1 at 5C), and good long-term durability (672.4 mA h g-1 at 1C after 500 cycles with a low decay rate of 0.066% per cycle). Even at a high sulfur loading of 5.6 mg cm-2, the battery still delivers a decent reversible capacity of 658.8 mA h g-1 at 0.2C after 100 cycles, indicating its great potential for practical applications. This work could provide a rational viewpoint for developing high-efficiency sulfur electrocatalysts towards future advanced Li-S energy storage systems. Oxygen-incorporated heterophase cobalt vanadium selenide nanoplates with dense crystalline/amorphous interfacial sites (DC/A O-CoVSe NPs) are developed as high-efficiency sulfur electrocatalysts for lithium-sulfur batteries.