Boosting High-Voltage Practical Lithium Metal Batteries with Tailored Additives

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal anodes offer high energy density but suffer from dendrite growth and low Coulombic efficiency (CE).
• Ether-based electrolytes are promising but require stabilization for practical lithium metal battery applications.

Purpose of the Study:

• To develop a stable ether-based electrolyte for high-performance lithium metal batteries.
• To enhance lithium anode stability and Coulombic efficiency using dual-salt additives.
• To improve the high-voltage performance and cycling stability of lithium metal pouch cells.

Main Methods:

• Formulation of an ether-based electrolyte (FGN-182) with lithium bis(fluorosulfonyl)imide (LiFSI) and lithium nitrate (LiNO3) as dual salts.
• Characterization of the solid electrolyte interphase (SEI) film and Li+ transport kinetics.
• Testing of Li||Cu half cells and pouch cells with high-loading lithium cobalt oxide (LCO) cathodes and ultrathin Li anodes.

Main Results:

• The dual-salt electrolyte facilitated a robust SEI film with enhanced Li+ transport, achieving an average CE of 99.56% in Li||Cu cells.
• Pouch cells demonstrated excellent cycling stability, retaining 80% capacity after 125 cycles with high-capacity LCO cathodes.
• Incorporation of 1,3,6-tricyanohexane improved high-voltage (4.4 V) LCO||Li pouch cell cycling, sustaining performance over 93 cycles.

Conclusions:

• The FGN-182 electrolyte with dual salts enables ultra-stable lithium metal anodes, overcoming common limitations.
• The strategy of using functional additives for both cathode and anode significantly improves Li utilization and electrolyte tolerance at high voltages.
• This research paves the way for practical, high-energy-density batteries utilizing lithium metal anodes with ether-based electrolytes.