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

Abstract

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.