LiFSA-KFSA binary molten salt enables durable lithium-antimony batteries at 80-100 °C

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Decarbonized energy systems require efficient grid storage.
• Traditional high-temperature molten-salt batteries face engineering and cost challenges.
• Lithium-antimony (Li‖Sb) batteries show promise but require lower operating temperatures.

Purpose of the Study:

• To develop a practical, mid-temperature Li‖Sb molten-salt battery for grid storage.
• To investigate the electrochemical performance and stability of the new system.
• To understand the underlying mechanisms of charge storage and cycling.

Main Methods:

• Utilized a lithium bis(fluorosulfonyl)imide and potassium bis(fluorosulfonyl)imide (LiFSA-KFSA) binary molten salt electrolyte.
• Operated the Li‖Sb battery at 80-100 °C.
• Employed in situ synchrotron X-ray characterization to study electrode behavior.

Main Results:

• Achieved high energy density (∼308.78 Wh kg^-1) and power density (∼8958.12 W kg^-1).
• Demonstrated remarkable long-term cyclability, retaining 48.68% capacity over 2000 cycles.
• Elucidated reversible phase evolution in antimony (Sb) facilitated by a stabilizing solid-electrolyte interphase.

Conclusions:

• Redefined Li‖Sb batteries as a practical mid-temperature energy storage technology.
• The developed system offers a durable and potentially low-cost solution for grid-scale applications.
• Anion-derived solid-electrolyte interphase plays a crucial role in stabilizing the electrode material.