Zwitterionic Polymer Electrolytes With Dipole-Rotation-Assisted Ion Conduction for Solid Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes are crucial for advanced lithium metal batteries.
• A key challenge is balancing high ionic conductivity with robust interfacial stability.

Purpose of the Study:

• To develop a molecular rotor strategy for solid polymer electrolytes.
• To enhance ion transport and interfacial properties in polyvinylidene difluoride-based electrolytes.

Main Methods:

• Incorporation of 3-(1-Pyridinio)-1-propanesulfonate zwitterions (PP-Z) into a polyvinylidene difluoride matrix.
• Utilizing molecular dynamics simulations and experimental electrochemical testing.
• Investigating dipole-rotation-assisted ion transport mechanisms.

Main Results:

• Achieved high ionic conductivity (5.1 × 10⁻⁴ S cm⁻¹ at 25°C) and Li⁺ transference number (0.52).
• Demonstrated stable cycling for 1200 hours in Li||Li cells and over 500 cycles in Li||LiFePO₄ cells.
• Maintained 85.1% capacity at 0°C in a Li||LiNi₀.₈Co₀.₁Mn₀.₁O₂ pouch cell over 50 cycles.

Conclusions:

• The molecular rotor strategy effectively enhances ionic conductivity and interfacial stability.
• This approach offers a promising pathway for developing high-performance lithium metal batteries.
• The PP-Z zwitterions facilitate efficient Li⁺ transport and promote a stable solid electrolyte interphase.