A ZIF-8 modified aramid nanofiber separator against the shuttle effect for high performance lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries are considered the most promising energy storage systems due to their high specific capacity and energy density. However, the practical application of lithium-sulfur batteries has been hampered by capacity loss due to the shuttle effect and serious safety issues due to the flammability and shrinkage of commercial diaphragms at high temperatures. Herein, we designed a separator by adding ZIF-8 nanoparticles to aramid nanofibers named ZIF-8/ANF. ANF has high flame retardant property and high mechanical strength to prevent separators failure at high temperature, preventing lithium dendrites from punctured separators and causing short circuit. ZIF-8 has the porous structure, while exposing abundant metal nodes acting as active sites, which can effectively adsorb polysulfides and inhibit the shuttle effect. As a result, the Li-S batteries with ZIF-8/ANF separators exhibit high specific discharge capacity and cycle performance. The Li-S batteries show a high initial specific capacity of 1178.3 mAh g−1 at 0.1 C and 525.9 mAh g−1 after 400 cycles. In addition, they also exhibit discharge capacity is 825.6 mAh g−1 at 0.2 C with the loading of 3.5 mg cm−2. This work offers a guidance for safe and high-performance Li-S batteries.