Catalyst and electrolyte synergy in Li-O2 batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-oxygen (Li-O2) batteries offer high theoretical energy density but suffer from poor cycle life and efficiency.
• Catalyst-electrolyte interactions are critical for improving Li-O2 battery performance, influencing capacity, efficiency, and stability.
• Understanding these interactions is key to unlocking the potential of next-generation energy storage.

Purpose of the Study:

• To investigate the synergistic effects between supported noble metal catalysts (Pt/C, Pd/C, Au/C) and common Li-O2 electrolyte solvents (DME, TEGDME, DMSO).
• To assess the impact of these catalyst-electrolyte combinations on stability, kinetics, and activity in Li-O2 systems.
• To identify optimal pairings for enhanced Li-O2 battery performance.

Main Methods:

• Systematic pairing of noble metal catalysts (Pt/C, Pd/C, Au/C) with different electrolyte solvents (DME, TEGDME, DMSO).
• Electrochemical characterization including cyclic voltammetry and full cell cycling experiments.
• Ex situ Energy-Dispersive Spectroscopy (EDS) and in situ Electrochemical Impedance Spectroscopy (EIS) for analyzing cathode species and resistance.

Main Results:

• A synergistic effect was observed between Pt and Pd catalysts and DMSO, significantly enhancing oxygen reduction and evolution kinetics.
• DME and TEGDME electrolytes showed greater susceptibility to decomposition and less favorable kinetics compared to DMSO.
• Catalyst-DMSO combinations achieved up to 9 times higher discharge capacities than catalyst-TEGDME combinations after 20 cycles (e.g., ~707.4 vs. 78.8 mA h g(-1) with Pd/C).
• Ex situ and in situ analyses indicated that improved capacity in DMSO is linked to higher electrolyte conductivity and catalyst synergies.

Conclusions:

• Co-selection of catalysts and electrolytes is essential for maximizing performance in Li-O2 batteries.
• The combination of Pt or Pd catalysts with DMSO electrolytes offers a promising strategy for improving capacity, kinetics, and stability.
• DMSO-based electrolytes, coupled with appropriate catalysts, demonstrate superior performance over DME and TEGDME in Li-O2 systems.