84 / 2021-06-15 09:36:30

An aramid nanofiber@MOFs composite separators for advanced Lithium-Sulfur Batteries

lithium sulfur battery; metal-organic frameworks; polysulfide; battery capacity,aramid nanofiber;

Lithium-sulfur (L-S) battery  is an extraordinarily prospective alternative rechargeable energy system to be applied in the electronic devices with high energy density due to its excellent theoretical energy density (2600 Whkg^-1). As an indispensable component of batteries, separators play an important role in preventing short circuits and providing ion transport channels. The commercial polyolefins based separators often suffer from poor thermostability, inferior electrolyte wettability, low ion conductivity and polysulfide intermediates (Li₂S_n, 2<n≤8) across induce a low utilization of sulfur and a serious decrease of capacity of Li-S batteries. Herein, we designed and fabricated a unique high performance composite aramid nanofibers (ANFs)@MOFs separator by vacuum assisted filtration (VAF) following by the in-situ growth of Co-containing zeolitic imidazolate framework (ZIF-L(Co)). Benefiting from the feature of high-strength of aramid nanofibers and high porosity and sufficient reaction area of MOFs, the obtained ANFs@MOFs separator guarantees high mechanical strength and remarkable thermal stability. Simultaneously, the in-situ leaf-shaped secondary nanostructures of ZIF-L(Co) is not only beneficial to the high-flux lithium-ion transport and fast electrolyte diffusion but also can provide the large surface area and abundant metal active sites to facilitate the suppression of the Li₂S_x shuttle effect. The Li-S battery equipped with the achieved ANFs@MOFs separator delivers a high charging/discharging performance, highlighting its promising commercial prospect for future high-safety and high-performance energy storage systems.