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.

Keywords

• interlayers
• lithium–sulfur batteries
• metal–organic frameworks
• mixed‐matrix membranes
• modeling
• solid‐state nuclear magnetic resonance