High Performance Ternary Solid Polymer Electrolytes Based on High Dielectric Poly(vinylidene fluoride) Copolymers for...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Efficient energy storage is critical for renewable energy sources.
• Lithium-ion batteries (LIBs) face challenges in safety and cycling stability.
• Solid polymer electrolytes (SPEs) offer a promising alternative to conventional liquid electrolytes/separators.

Purpose of the Study:

• To develop and investigate ternary SPEs for improved LIB performance.
• To evaluate the impact of different polymer matrices (PVDF-HFP, P(VDF-TrFE-CFE)), fillers (clinoptilolite), and ionic liquids (ILs) on SPE properties.
• To demonstrate the suitability of P(VDF-TrFE-CFE) as a host polymer for SPEs in LIBs.

Main Methods:

• Fabrication of ternary SPEs using doctor blade technique with solvent evaporation.
• Characterization of SPE morphology, mechanical, and electrochemical properties.
• Electrochemical testing including ionic conductivity, electrochemical window, transference number, and charge-discharge cycling performance.

Main Results:

• The PVDF-HFP-CPT-[PMPyr][TFSI] SPE achieved the highest ionic conductivity (4.2 × 10⁻⁵ S cm⁻¹) and lithium transference number (0.59).
• All developed SPEs exhibited excellent battery performance, delivering 150 mAh g⁻¹ after 50 cycles at C/10.
• The P(VDF-TrFE-CFE) based SPE demonstrated superior rate performance, with a discharge value of 98.7 mAh g⁻¹ at a C-rate, indicating enhanced ionic dissociation.

Conclusions:

• The selection of polymer matrix, ionic liquid, and lithium salt is crucial for optimizing ternary SPE performance in solid-state LIBs.
• P(VDF-TrFE-CFE) shows significant potential as a host polymer for SPEs, improving battery cyclability across various discharge rates.
• The study validates the use of ILs for enhancing ionic conductivity and highlights the benefits of P(VDF-TrFE-CFE) for stable LIB operation.