Sulfonic acid functionalized Al-based MIL-101-NH2 modified separator for lithium-sulfur batteries.

The transmembrane diffusion of soluble lithium polysulfides (LiPS) is the main cause of capacity loss and negative electrode corrosion in lithium-sulfur (Li-S) batteries. In order to suppress the shuttle effect of LiPS, a selective permeability membrane was constructed by introducing functional materials with negative charge groups. Herein, a functional separator with high ion conductivity is obtained by casting the environmentally friendly MOF material sulfonic acid functionalized amino-MIL-101 (S-MIL-101) onto the separator. It is found that the functionalized sulfonic acid group not only accelerates the conduction of the lithium-ion but also repels the polysulfide anion through electrostatic interactions. With this functionalized separator, the initial capacity of batteries is 1444.6 mAh·g−1 at 0.2C and remains 990.4 mAh·g−1 after 100 cycles. Meanwhile, the batteries still deliver a high initial discharge capacity of 895.7 mAh·g−1 even with the high-sulfur-loading cathode (4.7 mg cm−2) at 0.2C. We designed and synthesized sulfonic acid functionalized Al-based MIL-101-NH 2 modified separator for lithium-sulfur batteries. The introduction of sulfonic acid groups can accelerate the conduction of Li+ and carry out electrochemical processes. Besides, negatively charged sulfonic acid groups can suppress the shuttle effect through electrostatic interaction. The lithium-sulfur batteries assembled with the S-MIL-101 separator have an initial discharge capacity of 895.7 mAh·g−1 at 0.2C with 4.7 mg cm−2. [Display omitted] • S-MIL-101 improves Li+ conductivity. • Modified separators inhibit shuttle effect. • Modified separators inhibit shuttle effect. [ABSTRACT FROM AUTHOR]