Composite Gel Polymer Electrolyte for Improved Cyclability in Lithium-Oxygen Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Developing advanced electrolytes is crucial for improving lithium-oxygen battery performance.
• Gel polymer electrolytes (GPEs) offer potential but often face limitations in ionic conductivity and stability.
• Composite GPEs (cGPEs) incorporating fillers are explored to overcome these challenges.

Purpose of the Study:

• To develop and evaluate novel composite gel polymer electrolytes (cGPEs) using one-dimensional glass microfillers for lithium-oxygen batteries.
• To investigate the impact of these cGPEs on ionic conductivity, lithium transference number, and cycling stability.
• To elucidate the mechanisms behind performance improvements in lithium-oxygen batteries utilizing cGPEs.

Main Methods:

• Fabrication of free-standing cGPE films using glass microfillers, tetraglyme solvent, UV-curable polymer, and lithium salt.
• Electrochemical characterization including ionic conductivity and lithium transference number measurements.
• Battery cycling performance evaluation and post-mortem analysis using electrochemical impedance spectroscopy, Raman spectroscopy, and scanning electron microscopy.

Main Results:

• cGPEs with 1 wt% microfillers exhibited significantly enhanced ionic conductivity and lithium transference number compared to GPEs.
• Lithium transference number improvements reached up to 50% and 28% at different salt concentrations.
• Lithium-oxygen batteries with cGPEs demonstrated substantially increased cycling stability, with up to 400% more cycles at 0.1 mol kg^-1 salt concentration.

Conclusions:

• The incorporation of glass microfillers in GPEs effectively enhances their electrochemical properties for lithium-oxygen batteries.
• cGPEs mitigate electrolyte decomposition and lithium carbonate formation on the cathode surface, prolonging battery lifespan.
• The improved lithium transference number in cGPEs stabilizes the electrolyte, reducing parasitic reactions and enhancing overall battery performance and longevity.