Halogenated Functional Electrolyte Additive for Li-CO₂ Batteries.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Functional electrolyte additives are crucial for Li-CO2 batteries, impacting CO2 evolution (CO2ER) and reduction (CO2RR) reactions.
• Existing additives have limited and varied functions, necessitating further research into their multiple impacts.

Purpose of the Study:

• To investigate the multiple impacts of functional electrolyte additives in Li-CO2 batteries.
• To explore the relationship between molecular structure and electrochemical performance of additives.
• To enable targeted design of new additives for rechargeable batteries.

Main Methods:

• Investigated N-phenylpyrrolidine (PPD) and 1-(3-bromophenyl) pyrrole (Br-PPD) as electrolyte additives.
• Evaluated CO2ER charging potentials and Li||Li symmetric cell cycling stability.
• Analyzed the formation of a stable solid electrolyte interphase (SEI) on Li metal anodes.

Main Results:

• PPD reduced the CO2ER charging potential to 3.65 V.
• Br-PPD enabled 800 h of stable cycling in Li||Li cells due to a protective SEI.
• Br-PPD-based Li-CO2 cells maintained 3.70 V for 120 cycles with a Super P cathode.

Conclusions:

• Functional electrolyte additives significantly impact Li-CO2 battery performance.
• The structural properties of organic molecules correlate with their electrochemical applications.
• This study provides insights for designing effective additives for advanced rechargeable batteries.