Rechargeable Li/Cl₂ Battery Down to -80 °C

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Low-temperature rechargeable batteries are crucial for applications in cold climates, polar expeditions, deep-sea exploration, and space missions.
• Existing battery technologies often suffer performance degradation at sub-zero temperatures, limiting their operational range.

Purpose of the Study:

• To develop and characterize a novel rechargeable lithium/chlorine (Li/Cl2) battery system capable of operating efficiently at temperatures as low as -80 °C.
• To investigate the electrochemical performance and cycling stability of the proposed battery chemistry under extreme low-temperature conditions.

Main Methods:

• Fabrication of a Li/Cl2 battery utilizing a lithium metal anode, a carbon dioxide (CO2) activated porous carbon cathode (KJCO2), and a novel electrolyte.
• Electrolyte composition: aluminum chloride (AlCl3), lithium chloride (LiCl), and lithium bis(fluorosulfonyl)imide (LiFSI) in thionyl chloride (SOCl2).
• Electrochemical characterization including charge-discharge cycling, galvanostatic performance testing, mass spectrometry, and X-ray photoelectron spectroscopy (XPS).

Main Results:

• The Li/Cl2 battery achieved operating voltages between 3.5-4 V at temperatures down to -80 °C.
• Demonstrated high first discharge capacities ranging from 100-4500 mAh g-1 (based on carbon mass) and reversible capacities of 1200-5000 mAh g-1 over 130 cycles.
• Identified the trapping of chlorine species (Cl2, SCl2, S2Cl2) within the porous carbon cathode during charging, enabling reversible reduction at distinct voltage plateaus (-80 °C: ~4 V for SCl2/S2Cl2 reduction, ~3.1 V for Cl2 reduction).

Conclusions:

• The developed Li/Cl2 battery system exhibits promising performance for low-temperature energy storage applications.
• The novel electrolyte and porous carbon cathode facilitate efficient charge transfer and reversible chlorine species cycling at -80 °C.
• This work paves the way for reliable power sources in extreme cold environments, including space exploration and polar research.