Ionic Liquid Functionalized Gel Polymer Electrolytes for Stable Lithium Metal Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Metallic lithium (Li) is an ideal anode material for lithium-ion batteries due to its high energy density.
• However, Li dendrite growth and poor interfacial stability hinder practical applications of Li metal anodes.
• Existing electrolytes face challenges in achieving both high ionic conductivity and Li ion transference number.

Purpose of the Study:

• To develop a gel polymer electrolyte that overcomes the limitations of Li metal anodes.
• To enhance ionic conductivity and Li ion transference number for improved battery performance.
• To suppress Li dendrite growth and ensure long-term cycling stability.

Main Methods:

• Synthesized a gel polymer electrolyte with imidazolium ionic liquid end groups and a perfluorinated alkyl chain (F-IL).
• Incorporated Lewis-acidic segments in the polymer backbone to alter salt solubility and Li+ binding affinity.
• Investigated the electrolyte's ionic conductivity, Li+ transference number, electrochemical stability, and performance in Li|Li symmetric and Li-S full cells.

Main Results:

• Achieved high ionic conductivity (9.16×10⁻³ S/cm) and a high Li+ transference number (0.69).
• Demonstrated excellent electrochemical stability up to 4.55 V, effectively suppressing Li dendrite growth.
• Exhibited stable cycling in Li|Li symmetric cells (9 mAh/cm² for >1800 hours) and retained 86.7% capacity in Li-S full cells after 250 cycles.

Conclusions:

• The novel gel polymer electrolyte with F-IL moieties significantly enhances Li metal anode performance.
• The unique structural features improve Li+ transport and interfacial stability, enabling dendrite suppression.
• This advancement holds promise for developing safer and more efficient next-generation lithium-ion batteries.