Improved lithium ion dynamics in crosslinked PMMA gel polymer electrolyte.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Current lithium-ion batteries often use PVDF-HFP based gel polymer electrolytes.
• There is a need for more cost-effective and environmentally friendly electrolyte materials.
• PMMA-based gels present a promising alternative due to lower financial and environmental costs.

Purpose of the Study:

• To investigate the solvation and transport properties of lithium ions in crosslinked PMMA-based gel polymer electrolytes.
• To evaluate the potential of PMMA-based gels as substitutes for PVDF-HFP gels in lithium-ion batteries.
• To understand the role of polymer-ion interactions on lithium ion mobility.

Main Methods:

• Combination of thermal and electrochemical methods.
• Raman spectroscopy.
• Pulse field gradient (PFG) and electrophoretic NMR (eNMR) techniques.
• Ab initio calculations.

Main Results:

• PMMA-based gel electrolytes show only a 14% reduction in conductivity compared to liquid electrolytes at 10 wt% polymer concentration.
• Co-solvation by polymer ester groups positively impacts lithium transport, enhancing ionic dissociation and decorrelating lithium mobility from anionic mobility.
• Gels exhibit better ionic dissociation and higher lithium transference numbers than their liquid fractions, leading to improved cationic conductivity.

Conclusions:

• Crosslinked PMMA-based gel polymer electrolytes are viable, cost-effective alternatives for lithium-ion batteries.
• Weak interactions between lithium ions and PMMA ester groups enhance lithium transport and ionic dissociation.
• These electrolytes offer improved cationic conductivity and transference numbers, despite a slight overall conductivity decrease.