Non-polar ether-based electrolyte solutions for stable high-voltage non-aqueous lithium metal batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Ether-based electrolytes are crucial for high-voltage lithium metal batteries but suffer from electrochemical instability.
• This instability limits their practical application and cycle life in demanding battery systems.

Purpose of the Study:

• To develop a dilution strategy for non-aqueous electrolytes to overcome the electrochemical instability of ether-based solutions.
• To enable the use of these improved electrolytes in high-voltage lithium metal batteries.

Main Methods:

• Investigated a dilute non-polar dipropyl ether (DPE)-based electrolyte with lithium bis(fluorosulfonyl) imide salt.
• Analyzed the decomposition order of solvated species to favor salt-derived anion cluster decomposition over solvent molecules.
• Fabricated pouch cells using Li metal anodes and LiNi0.8Co0.1Mn0.1O2 cathodes.

Main Results:

• The dilution strategy successfully adjusted the decomposition order, promoting selective decomposition of salt-derived species.
• Formation of a robust cathode electrolyte interphase (CEI) and a solvent-deficient electric double-layer structure was observed.
• Pouch cells demonstrated approximately 74% capacity retention after 150 cycles at 0.33 mA/cm² charge and 1 mA/cm² discharge.

Conclusions:

• The proposed dilution strategy effectively enhances the electrochemical stability of ether-based electrolytes for high-voltage lithium metal batteries.
• This approach leads to improved interfacial properties and extended cycle life, paving the way for practical applications.