New Electrode and Electrolyte Configurations for Lithium-Oxygen Battery

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-oxygen batteries offer high theoretical energy density but face challenges in electrode stability and reaction reversibility.
• Ionic liquid electrolytes are explored to improve safety and electrochemical performance in lithium-oxygen systems.
• Developing robust cathode configurations is crucial for efficient oxygen reduction and evolution reactions.

Purpose of the Study:

• To investigate novel cathode configurations for lithium-oxygen batteries utilizing ionic liquid electrolytes.
• To compare the electrochemical performance of self-standing electrodes (SSEs) and spray-deposited electrodes (SDEs).
• To evaluate the reversibility and efficiency of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in these systems.

Main Methods:

• Fabrication of roll-pressed, self-standing electrodes (SSEs) and spray-deposited electrodes (SDEs) using high surface area carbon and polytetrafluoroethylene (PTFE).
• Electrochemical characterization of electrodes in lithium-oxygen cells with an ionic liquid electrolyte (LiTFSI/DEMETFSI).
• Performance evaluation including charge/discharge polarization, capacity, and energy efficiency at 60°C.

Main Results:

• Both SSEs and SDEs exhibited reversible electrochemical reactions in the lithium-oxygen cells.
• SSEs demonstrated superior performance with lower charge/discharge polarization (0.4 V) and higher energy efficiency (88%) compared to SDEs (0.6 V polarization, 80% efficiency).
• A full lithium-ion oxygen cell using SSEs, DEMETFSI-LiTFSI electrolyte, and a LiₓSn-C alloy anode showed exceptionally low polarization and high energy efficiency.

Conclusions:

• Self-standing electrodes represent a promising alternative cathode configuration for advanced lithium-oxygen batteries.
• The combination of SSEs with ionic liquid electrolytes enhances the reversibility and efficiency of ORR/OER processes.
• These findings pave the way for developing more efficient and stable lithium-oxygen energy storage systems.