Unraveling the Mechanisms of Zirconium Metal–Organic Frameworks-Based Mixed-Matrix Membranes Preventing Polysulfide Shuttling

Abstract

Lithium–sulfur batteries are considered as promising candidates for next-generation energy storage devices for grid applications due to their high theoretical energy density. However, the inevitable shuttle effect of lithium polysulfides and/or dendrite growth of Li metal anodes hinder their commercial viability. Herein, the microporous Zr fumarate metal–organic framework (MOF)-801(Zr) is considered to produce thin (≈15.6 μm, ≈1 mg cm2) mixed-matrix membranes (MMM) as a novel interlayer for Li–S batteries. It is found that the MOF-801(Zr)/C/PVDF-HFP composite interlayer facilitates Li+ ions diffusion, and anchors polysulfides while promoting their redox conversion effectively. It is demonstrated that MOF-801 effectively trapped polysulfides at the cathode side, and confirmed for the first time the nature of the interaction between the adsorbed polysulfides and the host framework, through a combination of solid-state nuclear magnetic resonance and molecular dynamics simulations. The incorporation of MOF-801(Zr)/C/PVDF-HFP MMM interlayer results in a notable enhancement in the initial capacity of Li–S batteries up to 1110 mA h g−1. Moreover, even after 50 cycles, a specific capacity of 880 mA h g−1 is delivered.