Highly Stable Lithium-Sulfur Batteries Based on Laponite Nanosheet-Coated Celgard Separators

Lithium-sulfur (Li-S) batteries are of great interest due to their high theoretical energy density. However, one of the key issues hindering their real world applications is polysulfide shuttle, which results in severe capacity decay and self-discharge. Here, a laponite nanosheets/carbon black coated Celgard (LNS/CB-Celgard) separator to inhibit polysulfide shuttle and to enhance the Li+ conductivity simultaneously is reported. The polysulfide shuttle is efficiently inhibited through strong interactions between the O active sites of the LNS and polysulfides by forming the Li...O and O-S bonds. Moreover, the separator features high Li+ conductivity, fast Li+ diffusion, excellent electrolyte wettability, and high thermal stability. Consequently, the Li-S batteries with the LNS/CB-Celgard separator and the pure S cathode show a high initial reversible capacity of 1387 mA h g(-1) at 0.1 C, high rate performance, superior cycling stability (with a capacity decay rate of 0.06% cycle(-1) at 0.2 C and 0.028% cycle(-1) at 1.0 C over 500 cycles), and ultralow self-discharge. The separator could also enhance the performance of other batteries such as the LiFePO4/separator/Li battery. This work sheds a new light on the design and preparation of novel separators for highly stable Li-S batteries via a "green" and cost-effective approach.