Nitro-functionalized Fe-MOFs for lithium-sulfur batteries

Abstract

Energy storage by means of lithium-sulfur batteries holds great promise. They are inexpensive and have a high potential energy density. Unfortunately, the battery's cycling performance is greatly diminished by the shuttle effect of polysulfide. Metal-organic frameworks (MOFs) with high specific surface area, nanopore size, and plentiful porosity have been proven to help prevent polysulfide migration in recent years. In this research, partially nitro-functionalized MIL-101(Fe) has been produced by combining different proportion ligands. As an electron-withdrawing group, the nitro group can reduce the charge density of the metal sites and improve the adsorption capacity of the material to polysulfides. MIL-101-NO2-0.25 showed the performance with an initial discharge capacity of 1051.5 mAh g-1 at a current density of 0.5 C and maintained at 908 mAh g-1 after 250 cycles.