Critical CO₂ Concentration for Practical Lithium-Air Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-air batteries offer high theoretical energy density, making them promising for next-generation energy storage.
• Carbon dioxide (CO2) is typically considered an impurity in Li-air batteries, leading to performance degradation through lithium carbonate (Li2CO3) formation.

Purpose of the Study:

• To quantitatively assess the impact of low CO2 concentrations (below 1000 ppm) on Li-air battery performance.
• To investigate the tolerance of Li-air batteries to CO2 and understand the underlying mechanisms.

Main Methods:

• Electrochemical characterization of Li-air batteries exposed to varying low CO2 concentrations.
• Quantification of lithium carbonate (Li2CO3) byproduct formation.
• In situ electrochemical impedance spectroscopy (EIS) combined with distribution of relaxation time (DRT) analysis.

Main Results:

• Li-air batteries demonstrated similar discharge capacities and cyclability with CO2 concentrations below 100 ppm compared to CO2-free conditions.
• Batteries with 0, 50, and 100 ppm CO2 achieved 85, 88, and 83 cycles, respectively.
• Lithium carbonate formation and its impact were analyzed using EIS and DRT.

Conclusions:

• Low concentrations of CO2 (below 100 ppm) do not significantly impair the electrochemical performance of Li-air batteries.
• This study provides a theoretical foundation for designing CO2 management strategies in Li-air battery systems.