A Fluoroether Co-Solvent Engineering Interfacial and Solvation Dynamics for Durable Lithium-Oxygen Batteries.

Area of Science:

• Energy Storage
• Electrochemistry
• Materials Science

Background:

• Lithium-oxygen batteries (LOBs) offer high theoretical energy density but face challenges.
• Key issues include electrolyte instability, lithium anode degradation, and poor reversibility of discharge products.

Purpose of the Study:

• To design a novel electrolyte additive for improving LOB performance.
• To address electrolyte volatility and enhance the stability of the lithium metal anode.
• To promote the formation of a more reversible lithium peroxide discharge product.

Main Methods:

• Synthesized a novel fluorinated ether co-solvent (FTE).
• Incorporated FTE into a tetraethylene glycol dimethyl ether (TEG-based) electrolyte.
• Investigated the impact of FTE on the solid electrolyte interphase (SEI) formation and Li+ solvation structure.
• Evaluated the electrochemical performance of LOBs using the modified electrolyte.

Main Results:

• FTE demonstrated a high boiling point, suppressing electrolyte evaporation.
• A fluorine-rich SEI layer formed on the lithium anode, enhancing interfacial stability.
• FTE modulated Li+ solvation, leading to a highly decomposable 3D porous Li2O2 structure.
• LOBs with FTE/TEG-based electrolyte exhibited improved cycling stability, high capacity, and excellent rate capability.

Conclusions:

• The novel FTE co-solvent effectively enhances LOB performance by addressing key challenges.
• This multifunctional electrolyte design strategy promotes long-term reversibility for practical high-energy-density LOBs.
• The study paves the way for advanced lithium-oxygen battery development.