Metal-organic framework-derived heterostructural bi-phased Sm2O3 as a novel sulfur immobilizer for high-performance Lithium-sulfur batteries

Abstract

Owing to their high theoretical energy density, low cost, and eco-friendliness, lithium‑sulfur (Li-S) batteries are one of the most promising alternatives to Li-ion batteries. However, the commercialization of Li-S batteries has been hampered by their rapid capacity fading and poor cycling lifetime due to the shuttling and sluggish redox kinetics of polysulfides (LiPSs). To address these issues, functionalizing a commercial separator is a simple and effective strategy. In this study, we developed a novel modified polypropylene separator coated with samarium-based metal-organic framework-derived heterostructural bi-phased Sm2O3 (Bi-Sm2O3), which contains cubic Sm2O3 (C-Sm2O3) and monoclinic Sm2O3 (M-Sm2O3) phase in a single polycrystalline particle. The alleviated “shuttle effect” of LiPSs can be achieved by synergistic effect at the Bi-Sm2O3 surface mainly through strong adsorption of LiPSs on M-Sm2O3 surface followed by catalytic conversion over C-Sm2O3. An optimized Bi-Sm2O3-modified separator with a thickness of 150 μm can enable the Li-S battery to deliver an improved cycling and rate performance with a high specific capacity of 860.1 mAh g−1 at 2C and a low decay rate of 0.11 % per cycle over 500 cycles at 1C.