Synthesis of Ta₂O₅@rGO nanohybrid via a unique one-step hydrothermal approach as an efficient separator modifier for lithium-sulfur batteries

The advancement of lithium-sulfur (Li-S) batteries could be enhanced by effective catalysts that limit the shuttling of polysulfides (LiPSs) and promote their transformation. Here, a unique one-step hydrothermal approach is used to produce tantalum pentoxide nanoparticles wrapped in reduced graphene oxide (Ta₂O₅@rGO nanohybrid) and operate as an effective functional separator for Li-S batteries. The Lewis acid-base chemical interactions between sulfur species and Ta atoms achieve strong Ta-S and Li-O bonds, providing Ta₂O₅ catalytic properties in Li-S cells. The adsorption energy data, calculated by Density Functional Theory (DFT), indicate that Ta₂O₅@rGO has robust adsorption capacity for all lithium polysulfides, exhibiting enhanced stability for larger polysulfides (Li₂S₆ and Li₂S₈). Moreover, rGO-induced oxygen defects in Ta₂O₅ could accelerate interfacial electron transport and LiPSs entrapment, diffusion, and transformation. By enhancing the Li-S cell's capacity to 485 mAh g⁻¹after 700 cycles at 1.0C, the functional separator of Ta₂O₅@rGO-PP verifies its low-capacity degradation per cycle and excellent long-cyclic performance. Despite difficult circumstances like a sulfur loading of 4.5 mg cm⁻²and an electrolyte/sulfur (E/S) ratio of 6.0 μL mg⁻¹, Ta₂O₅@rGO-PP still managed to show a high capacity of 736 mAh g⁻¹after 100 cycles.