Green Polymer Electrolytes Prepared by a Cost-Effective Approach.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) often require fillers or modifications to improve conductivity.
• Polyethylene glycol (PEG) offers higher conductivity but lower mechanical strength compared to poly(ethylene oxide) (PEO).
• PEG is used as a plasticizer or in gel polymer electrolytes (GPEs).

Purpose of the Study:

• To develop novel SPEs and solvent-free GPEs using polyethylene glycol (PEG) and poly(l-lactide) (PLLA).
• To investigate the effect of incorporating 1,3:2,4-dibenzylidene sorbitol (DBS) on electrolyte properties.
• To enhance the electrochemical stability and mechanical support of polymer electrolytes for lithium-ion cells.

Main Methods:

• Blending low-molecular-weight PEG (400 g/mol) with PLLA to form solid PEG/PLLA electrolytes.
• Adding lithium salts to create novel PEG/PLLA SPEs.
• Incorporating DBS, an organic gelator, to form solvent-free GPEs via self-assembly into a nanofibrillar network.

Main Results:

• Prepared PEG/PLLA SPEs achieved a maximum conductivity of 4.39 × 10^-5 S/cm, five times higher than neat PEG SPEs.
• Ionic conductivity decreased with increasing PLLA and DBS content, but electrochemical stability improved.
• PLLA and DBS incorporation enhanced mechanical support, mitigating capacity decay and improving cycling performance in lithium-ion cells.

Conclusions:

• Novel PEG/PLLA-based SPEs and GPEs were successfully fabricated using a straightforward blending approach.
• The addition of PLLA and DBS improved the mechanical properties and electrochemical stability of the electrolytes.
• These enhanced electrolytes show promise for improving the performance and longevity of lithium-ion batteries.