Perfluoropolyether-terminated Single-ion Polymer for Enhancing Performance of PEO-based Solid Polymer Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state electrolytes are crucial for high-energy-density lithium metal batteries.
• Poly(ethylene oxide) (PEO) based electrolytes have limitations including low lithium-ion transference and poor high-voltage stability.
• These limitations hinder the practical application of PEO in advanced lithium metal batteries.

Purpose of the Study:

• To design and synthesize a novel perfluoropolyether-terminated single-ion polymer (PFPE-polymer).
• To develop an improved polymer electrolyte (PFPE-SE) for lithium metal batteries by incorporating PFPE-polymer into PEO.
• To evaluate the performance of the PFPE-SE electrolyte in terms of lithium-ion transference, electrochemical window, and cycling stability.

Main Methods:

• Synthesis of a perfluoropolyether-terminated single-ion polymer (PFPE-polymer).
• Preparation of the polymer electrolyte (PFPE-SE) by incorporating PFPE-polymer and LiTFSI into PEO via casting.
• Characterization of the PFPE-SE electrolyte's properties, including lithium-ion transference number, electrochemical window, and solid electrolyte interface (SEI) formation.
• Electrochemical testing of Li|PFPE-SE|LFP cells to assess capacity, cycling stability, and dendrite inhibition.

Main Results:

• The PFPE-SE electrolyte successfully forms a solid electrolyte interface (SEI) layer, inhibiting lithium dendrite growth.
• Achieved a high lithium-ion transference number of 0.72 and an electrochemical window of 4.7 V at 70 °C.
• The Li|PFPE-SE|LFP cell demonstrated a specific capacity of 156.0 mAh g⁻¹ at 0.5 C discharge rate.
• Exhibited superior cycling performance with 74.3% capacity retention after 230 cycles compared to PEO-LiTFSI electrolytes.

Conclusions:

• The developed PFPE-SE is a promising polymer electrolyte for high-performance lithium metal batteries.
• In situ SEI formation and single-ion conduction contribute to enhanced battery safety and efficiency.
• This strategy offers a viable pathway for advancing lithium metal battery technology.