Low Concentration Sulfolane-Based Electrolyte for High Voltage Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Electrolyte engineering is critical for advancing lithium metal battery commercialization.
• Highly reactive electrolytes pose challenges for lithium metal anode stability.

Purpose of the Study:

• To stabilize lithium metal in a low-concentration sulfolane-based electrolyte.
• To investigate the performance of lithium metal batteries using this novel electrolyte system.

Main Methods:

• Formation of an inorganic-polymer hybrid solid electrolyte interphase (SEI) on lithium metal.
• Electrochemical cycling of LiNi_0.5 Co_0.2 Mn_0.3 O₂ (NCM523)/Li cells with the low-concentration electrolyte (LCE).
• Evaluation of lithium deposition morphology and plating/stripping efficiency.

Main Results:

• Achieved stable lithium metal cycling in a 0.25 M sulfolane-based LCE for the first time.
• The hybrid SEI facilitated dense, chunky lithium deposition and high plating/stripping efficiency.
• Demonstrated excellent cycling stability for NCM523/Li cells at 1 C (90.7% retention after 500 cycles) and 0.3 C (83.3% retention after 1000 cycles).
• NCM523/Li cells with a low N/P ratio (≈2) showed 94.3% capacity retention after 100 cycles at 0.3 C.

Conclusions:

• Low-concentration electrolytes (LCEs) offer new possibilities for lithium salt selection and enable the use of previously unsuitable salts.
• LCEs present a cost-effective and commercially advantageous approach for lithium metal battery development.
• This study highlights the potential of electrolyte engineering with LCEs for high-performance and commercially viable lithium metal batteries.