Synergistic Effect of Bimetallic MOF Modified Separator for Long Cycle Life Lithium‐Sulfur Batteries

Synergistic Effect of Bimetallic MOF Modified Separator for Long Cycle Life Lithium‐Sulfur Batteries

Severe polysulfide dissolution and shuttling are the main challenges that plague the long cycle life and capacity retention of lithium‐sulfur (Li‐S) batteries. To address these challenges, efficient separators are designed and modified with a dual functional bimetallic metal‐organic framework (MOF)....

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Bibliographic Details
Published in:Advanced energy materials Vol. 14; no. 3
Main Authors: Razaq, Rameez, Din, Mir Mehraj Ud, Småbråten, Didrik Rene, Eyupoglu, Volkan, Janakiram, Saravanan, Sunde, Tor Olav, Allahgoli, Nima, Rettenwander, Daniel, Deng, Liyuan
Format: Journal Article
Language:English
Published: Weinheim Wiley Subscription Services, Inc 01-01-2024
Subjects:
adsorption
bimetallic MOF
Bimetals
dendrite formation
Discharge
electrocatalyst
Ion transport
Iron
Lithium
Lithium sulfur batteries
Metal-organic frameworks
polysulfide shuttle
Polysulfides
Pore size
Separators
Sulfur
Synergistic effect
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Summary:Severe polysulfide dissolution and shuttling are the main challenges that plague the long cycle life and capacity retention of lithium‐sulfur (Li‐S) batteries. To address these challenges, efficient separators are designed and modified with a dual functional bimetallic metal‐organic framework (MOF). Flower‐shaped bimetallic MOFs (i.e., Fe‐ZIF‐8) with nanostructured pores are synthesized at 35 °C in water by introducing dopant metal sites (Fe), which are then coated on a polypropylene (PP) separator to provide selective channels, thereby effectively inhibiting the migration of lithium polysulfides while allowing homogeneous transport of Li‐ions. The active sites of the Fe‐ZIF‐8 enable electrocatalytic conversion, facilitating the conversion of lithium polysulfides. Moreover, the developed separator can prevent dendrite formation due to the uniform pore size and hence the even Li‐ion transport and deposition. A coin cell using a Fe‐ZIF‐8/PP separator with S‐loaded carbon cathode displayed a high cycle life of 1000 cycles with a high initial discharge capacity of 863 mAh g−1 at 0.5 C and a discharge capacity of 746 mAh g−1 at a high rate of 3 C. Promising specific capacity has been documented even under high sulfur loading of 5.0 mg cm−2 and electrolyte to the sulfur ratio (E/S) of 5 µL mg−1. A multifunctional bimetallic MOF‐based separator is designed specifically for lithium‐sulfur batteries that can selectively block and convert polysulfides while providing even transport of lithium ions. Remarkably higher catalytic activity is found for the conversion of polysulfides by the Fe‐doped MOF (ZIF‐8) compared to the parent ZIF‐8. Meanwhile, the incorporation of Fe (II) centers into the ZIF framework dramatically improves the specific capacity and rate capability.
ISSN:1614-6832
1614-6840
DOI:10.1002/aenm.202302897