A Rotating Cathode with Periodical Changes in Electrolyte Layer Thickness for High-Rate Li‒O₂ Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-oxygen batteries (LOBs) offer high theoretical energy density but suffer from poor rate performance due to slow mass transfer.
• Addressing mass transfer limitations is crucial for the practical application of LOBs.

Purpose of the Study:

• To design and evaluate a novel rotating cathode system for enhancing mass transfer in LOBs.
• To decouple the mass transfer rates of lithium ions (Li+) and oxygen (O2) to improve battery performance.

Main Methods:

• A rotating cathode with periodically varying electrolyte layer thickness was engineered.
• The system was tested in LOBs to assess its impact on cycling stability, discharge capacity, and rate capability.

Main Results:

• The rotating cathode facilitated efficient O2 and Li+ transfer by creating alternating thin and thick electrolyte layers.
• LOBs with the rotating cathode achieved 58 cycles at 2.5 mA cm-2 and stable discharge at 7.5 mA cm-2.
• A large discharge capacity of 6.8 mAh cm-2 was observed, with significantly reduced capacity decay at higher current densities.

Conclusions:

• The rotating cathode effectively overcomes mass transfer limitations in LOBs, significantly enhancing their rate performance and cycling stability.
• This innovative electrode design shows potential for improving various electrochemical systems that involve gas-liquid-solid interfaces.