Using elastin protein to develop highly efficient air cathodes for lithium-O2 batteries

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Non-aqueous lithium-oxygen (Li-O2) batteries offer high theoretical energy density but face challenges with cathode material stability and performance.
• Developing efficient and durable cathode catalysts is crucial for advancing Li-O2 battery technology.

Purpose of the Study:

• To synthesize novel transition metal-nitrogen/carbon (M-N/C) catalysts using sustainable precursors for Li-O2 battery cathodes.
• To investigate the catalytic activity and electrochemical performance of these M-N/C catalysts in Li-O2 battery applications.

Main Methods:

• Synthesis of M-N/C (M = Fe, Co) catalysts via histidine-tag-rich elastin protein beads, metal sulfate, and carbon nanotubes, followed by annealing and acid leaching.
• Fabrication of cathode materials using the synthesized catalysts for non-aqueous Li-O2 batteries.
• Electrochemical characterization including galvanostatic cycling, capacity, current density, charge voltage, and energy efficiency measurements.

Main Results:

• The Fe-N/C catalyst-based cathodes achieved a high capacity of 12,441 mAh g⁻¹ at 100 mA g⁻¹.
• Stable cycling at a limited capacity of 800 mAh g⁻¹ demonstrated stable charge voltages of ~3.65 V (200 mA g⁻¹) and ~3.90 V (400 mA g⁻¹).
• Energy efficiencies of ~71.2% and ~65.1% were recorded at 200 and 400 mA g⁻¹, respectively, outperforming bare annealed carbon nanotubes.

Conclusions:

• The developed Fe-N/C catalysts, synthesized using eco-friendly protein beads and CNTs, are highly effective cathode materials for non-aqueous Li-O2 batteries.
• The catalysts facilitate efficient nucleation and growth of Li2O2, leading to enhanced battery performance and stability.
• These findings highlight the potential of M-N/C catalysts derived from sustainable sources for next-generation energy storage devices.