Stable Voltage Cutoff Cycle Cathode with Tunable and Ordered Porous Structure for Li-O₂ Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Carbon-based cathodes in lithium-oxygen (Li-O2) batteries suffer from parasitic reactions.
• Developing alternative cathode materials is crucial for improving Li-O2 battery performance and stability.

Purpose of the Study:

• To investigate the impact of pore structure parameters in ordered porous ruthenium dioxide (RuO2) on Li-O2 battery performance.
• To identify optimal pore characteristics for enhanced electrochemical efficiency and cycling stability.

Main Methods:

• Fabrication of ordered porous RuO2 materials using a hard-template method.
• Electrochemical testing of RuO2 cathodes in Li-O2 batteries under voltage cutoff cycling.
• In situ differential electrochemical mass spectrometry (DEMS) to analyze parasitic reactions.

Main Results:

• Specific surface area and pore size significantly influence specific capacity and round-trip efficiency.
• Pore blockage (too small) and weakened mechanical properties (too large) negatively impact performance.
• RuO2-16 (16 nm average pore size) achieved ~75.6% round-trip efficiency and 70 cycles at 100 mA g-1.
• RuO2 cathodes demonstrated reduced parasitic reactions compared to carbon materials.

Conclusions:

• Optimal pore structure parameters are key to superior performance in RuO2-based Li-O2 battery cathodes.
• Porous RuO2 offers a promising carbon-free alternative for advanced Li-O2 battery applications.
• RuO2's ability to suppress parasitic reactions contributes to enhanced cycling stability.