Zwitterionic Separator Featured with Superdesolvating Properties for High Performance Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium-sulfur (Li-S) batteries offer high energy density but suffer from parasitic reactions involving soluble sulfur intermediates (LiPSs) and lithium anodes.
• Controlling the solvation structures of lithium ions (Li+) and LiPSs is crucial for mitigating these issues.

Purpose of the Study:

• To develop a novel separator using zwitterionic nanoparticles (ZWP) to modulate the solvation environment of Li+ and LiPSs.
• To investigate the impact of ZWP separators on LiPSs shuttling, Li+ transport, and lithium metal anode stability.

Main Methods:

• Fabrication of a ZWP-based separator inspired by superhydrophilic surfaces.
• Characterization of solvation structures using molecular simulation and nuclear magnetic resonance (NMR).
• In situ UV setup to monitor LiPSs shuttle and electrochemical testing to evaluate battery performance.

Main Results:

• The ZWP separator induced a dense solvation layer, effectively hindering LiPSs movement while facilitating Li+ transport.
• ZWP demonstrated high electrolyte affinity, minimizing LiPSs deposition on the separator.
• Molecular simulations and NMR revealed insights into the solvation structures of Li+ and LiPSs.
• In situ UV and electrochemical tests confirmed suppressed LiPSs shuttle, stabilized lithium deposition, and regulated dendrite growth.
• Significantly improved performance and cycle stability were achieved, even at high sulfur loadings (5 mg cm-2).

Conclusions:

• Zwitterionic nanoparticles offer a promising strategy for designing advanced separators in lithium-sulfur batteries.
• Modulating solvation structures is key to overcoming the challenges associated with LiPSs shuttling and lithium anode degradation.
• The developed ZWP separator provides a new pathway for enhancing the practical application of high-energy lithium-sulfur batteries.