The Effects of Processing Conditions and Pressure on Composite Polymer Electrolyte Performance.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Liquid electrolytes in lithium batteries pose safety risks.
• Solid polymer electrolytes offer a safer alternative but face conductivity challenges.
• Inconsistent reporting in literature hinders accurate performance assessment of polymer electrolytes.

Purpose of the Study:

• To investigate the effect of polymer electrolyte composition and residual solvent on ionic conductivity.
• To understand how applied pressure influences the conductivity of composite polymer electrolytes.
• To develop reliable methods for evaluating polymer electrolyte performance.

Main Methods:

• Fabrication of composite polymer electrolytes using poly (vinylidene fluoride-co-hexafluoropropylene), succinonitrile, and lithium lanthanum zirconium tantalum oxide.
• Utilized a custom-designed test fixture to measure ionic conductivity under varying pressures (1.5-18.7 psi) and temperatures (10-90 °C).
• Performed symmetric cell testing to evaluate Coulombic efficiency and cycling stability.

Main Results:

• Applied pressure significantly affects measured ionic conductivity.
• Optimal composite film conductivity ranged from 1.2 × 10^-5 to 4.1 × 10^-5 S cm^-1 at room temperature.
• Conductivity exceeded 1 mS cm^-1 at elevated temperatures, with ideal pressure dependent on additives.
• Symmetric cells demonstrated >99% Coulombic efficiency over 100 cycles.

Conclusions:

• Accurate characterization of polymer electrolyte films is essential.
• Controlled testing apparatus pressure is critical for reliable conductivity data.
• Understanding pressure-dependent conductivity is key to developing high-performance polymer electrolytes for lithium batteries.