Reversible Hybrid Aqueous Li-CO₂ Batteries with High Energy Density and Formic Acid Production

Area of Science:

• Electrochemistry
• Energy Storage Systems
• Carbon Dioxide Utilization

Background:

• Metal-CO2 batteries offer dual benefits for energy storage and CO2 utilization.
• Existing organic Li(Na)-CO2 batteries provide high energy density, while aqueous Zn-CO2 batteries allow flexible chemical production.
• A challenge remains in achieving both high efficiency and flexible production in a single system.

Purpose of the Study:

• To develop a reversible hybrid aqueous Li-CO2 battery.
• To integrate high energy storage performance with selective chemical production.
• To address the limitations of current metal-CO2 battery technologies.

Main Methods:

• A hybrid aqueous Li-CO2 battery was constructed using a Li anode, NaCl electrolyte, LAGP solid electrolyte separator, and a Pd-based electrocatalyst cathode.
• The battery's performance was evaluated for voltage, energy conversion efficiency, and CO2-to-formic acid selectivity.
• Electrochemical reactions and mechanisms were investigated.

Main Results:

• The developed battery demonstrated a high discharge voltage of up to 2.6 V.
• An outstanding energy conversion efficiency exceeding 80% was achieved.
• Remarkable selectivity for CO2 to formic acid conversion reached up to 97%.

Conclusions:

• The hybrid aqueous Li-CO2 battery successfully integrates high energy storage with selective formic acid production.
• This technology presents a promising pathway for efficient CO2 utilization and energy storage.
• The proposed reaction mechanism (CO2 + 2Li + 2H+ ⇌ HCOOH + 2Li+) underpins the battery's functionality.