Comparing Internal and Interparticle Space Effects of Metal–Organic Frameworks on Polysulfide Migration in Lithium–Sulfur Batteries

Abstract

One of the critical issues hindering the commercialization of lithium–sulfur (Li–S) batteries is the dissolution and migration of soluble polysulfides in electrolyte, which is called the ‘shuttle effect’. To address this issue, previous studies have focused on separators featuring specific chemical affinities or physical confinement by porous coating materials. However, there have been no studies on the complex effects of the simultaneous presence of the internal and interparticle spaces of porous materials in Li–S batteries. In this report, the stable Zr-based metal–organic frameworks (MOFs), UiO-66, have been used as a separator coating material to provide interparticle space via size-controlled MOF particles and thermodynamic internal space via amine functionality. The abundant interparticle space promoted mass transport, resulting in enhanced cycling performance. However, when amine functionalized UiO-66 was employed as the separator coating material, the initial specific capacity and capacity retention of Li–S batteries were superior to those materials based on the interparticle effect. Therefore, it is concluded that the thermodynamic interaction inside internal space is more important for preventing polysulfide migration than spatial condensation of the interparticle space.

Metal‐Organic Framework/Graphene Nanoplatelet Composite Increases Rate Performance of Lithium–Sulfur Batteries

“…[20][21][22] UiO-66 is a zirconia-based MOF with a 1,4-benzene-dicarboxylate linker first developed by Cavka et al [23] It was proven that this MOF has high thermal and chemical stabilities and has an adjustable charge distribution on the surface, depending on the synthesis method. [24] Hence, UiO-66 has already been used in several studies in the Li-S battery literature [25][26][27][28][29][30] as a separator component to alleviate the PSM due to its adsorptive power toward the PSs. [26,28] UiO-66 has also been used in several forms as a cathode additive: lithiated, [31,32] phosphorus-functionalized, [33] and NH 2 -UiO-66-derived [34] composites.…”