γ-Ray irradiated polyacrylamide networks enable high-performance Li||S pouch cells

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Commercial binders in Li||S batteries have limitations including disordered networks and poor mechanical strength.
• Traditional cross-linked binder synthesis involves additives and results in poorly controlled polymer networks.
• Understanding the operando mechanisms of reticulated binders in stabilizing electrodes is crucial.

Purpose of the Study:

• To develop a novel method for creating 3D covalent binders for Li||S batteries.
• To investigate the role of binder architecture in stabilizing sulfur and enhancing electrode performance.
• To elucidate the operando mechanisms of binder-sulfur interactions.

Main Methods:

• Solid-state operando gamma-ray irradiation for binder synthesis.
• In situ optical frequency domain reflectometry for real-time analysis.
• Multiscale synchrotron radiation characterization and virtual simulations.
• Fabrication and testing of soft-packaged Li||S pouch cells.

Main Results:

• Additive-free, ordered polyacrylamide networks with enhanced binding capabilities were produced.
• Gamma-ray irradiation enabled binders improve mechanical strengthening, sulfur regeneration, and re-occupancy.
• A 1.2-Ah pouch cell achieved 410.1 Wh/kg specific energy at a low electrolyte/sulfur ratio.
• Binder-sulfur interactions were revealed, showing dynamic encaging and confinement of sulfur.

Conclusions:

• Solid-state gamma-ray irradiation is an effective method for tailoring 3D covalent binders.
• The developed binders significantly improve Li||S battery performance and energy density.
• The study provides insights into binder mechanisms for advanced battery applications.