High-Capacity Rechargeable Li/Cl₂ Batteries with Graphite Positive Electrodes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Developing high-capacity, high-energy density rechargeable batteries is crucial for consumer electronics, electric vehicles, and grid storage.
• Previous research demonstrated Na/Cl2 and Li/Cl2 batteries using amorphous carbon nanospheres (aCNS) with high reversible capacity.

Purpose of the Study:

• To investigate the potential of initially low surface area graphite (DGr) as a positive electrode material for Li/Cl2 batteries.
• To enhance graphite performance through CO2 activation and understand its electrochemical behavior.

Main Methods:

• Activation of DGr using CO2 at 1000 °C to create DGr_ac.
• Electrochemical testing of Li/Cl2 batteries with DGr_ac as the positive electrode.
• Ex situ Raman spectroscopy and X-ray diffraction (XRD) to analyze electrode evolution.
• Mass spectrometry to probe Cl2 trapping.

Main Results:

• Activated graphite (DGr_ac) achieved a first discharge capacity of ~1910 mAh g-1 and cycling capacity up to 1200 mAh g-1.
• Electrochemical cycling induced graphite exfoliation, creating pores for LiCl/Cl2 redox reactions.
• Mass spectrometry confirmed Cl2 trapping within the graphitic electrode.

Conclusions:

• Low-cost graphitic materials, when activated, are viable for high-capacity alkali metal/Cl2 batteries.
• Graphite activation and in-situ pore generation are key to high performance in Li/Cl2 systems.
• This work provides insights into the operational mechanisms of Li/Cl2 batteries.