Emerging catalytic materials for practical lithium-sulfur batteries

High-energy lithium-sulfur batteries (LSBs) have experienced relentless development over the past decade with discernible improvements in electrochemical performance. However, a scrutinization of the cell operation conditions reveals a huge gap between the demands for practical batteries and those in the literature. Low sulfur loading, a high electrolyte/sulfur (E/S) ratio and excess anodes for lab-scale LSBs significantly offset their high-energy merit. To approach practical LSBs, high loading and lean electrolyte parameters are needed, which involve budding challenges of slow charge transfer, polysulfide precipitation and severe shuttle effects. To track these obstacles, the exploration of electrocatalysts to immobilize polysulfides and accelerate Li-S redox kinetics has been widely reported. Herein, this review aims to survey state-of-the-art catalytic materials for practical LSBs with emphasis on elucidating the correlation among catalyst design strategies, material structures and electrochemical performance. We also statistically evaluate the state-of-the-art catalyst-modified LSBs to identify the remaining discrepancy between the current advancements and the real-world requirements. In closing, we put forward our proposal for a catalytic material study to help realize practical LSBs.