Suppressing Redox Shuttling with Lithiated Nafion-Modified Separators for Li-O₂ Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Redox mediators (RM) in lithium-oxygen (Li-O2) batteries reduce charging overpotential but cause shuttle effects, leading to degradation and limited cycle life.
• The shuttle effect involves undesirable side reactions of RMs with the lithium anode, compromising battery performance and safety.
• Developing strategies to mitigate these parasitic reactions is crucial for advancing Li-O2 battery technology.

Purpose of the Study:

• To introduce a functional lithiated Nafion-modified separator for Li-O2 batteries.
• To inhibit the redox shuttle effect through coulombic/electrostatic interactions.
• To enhance the cycling stability of RM-involved Li-O2 batteries.

Main Methods:

• Fabrication of a lithiated Nafion-modified separator using accessible materials and a scalable process.
• Systematic investigation of the electrochemical properties influenced by the lithiation process.
• Study of the impact of the decorated amount of lithiated Nafion on cycling stability.
• Analysis of the functional contribution of lithiated Nafion in suppressing redox shuttling.

Main Results:

• The lithiated Nafion-modified separator effectively inhibited the redox shuttle effect in RM-involved Li-O2 batteries.
• Coulombic/electrostatic interactions were identified as the mechanism for shuttle suppression.
• The modified separator demonstrated enhanced cycling stability compared to unmodified separators.
• The fabrication process is suitable for large-scale production.

Conclusions:

• A functional separator based on lithiated Nafion provides an effective solution to the redox shuttle problem in Li-O2 batteries.
• This approach enhances battery longevity by preventing mediator degradation and anode deterioration.
• The study offers insights into designing functional separators for suppressing parasitic reactions in advanced energy storage systems.