In Situ Formed Gel Polymer Electrolytes Enable Stable Solid Electrolyte Interface for High-Performance Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Carbonate electrolytes in high-voltage lithium metal batteries yield unstable solid-electrolyte interphases (SEI).
• Nonuniform and mechanically weak SEI layers hinder battery performance and longevity.

Purpose of the Study:

• To develop a homogeneous and mechanically robust SEI for lithium metal batteries.
• To improve the cycling stability and capacity retention of high-voltage lithium metal batteries.

Main Methods:

• Incorporating an in situ polymerized poly(hexamethylene diisocyanate)-based gel polymer electrolyte (GPE).
• Utilizing fluoroethylene carbonate (FEC) as an additive to form a LiF-rich SEI on lithium metal anodes.
• Testing Li symmetric cells and Li/LiFePO4 and Li/NCM811 battery configurations.

Main Results:

• Achieved stable cycling of Li symmetric batteries for 700 hours with inhibited byproduct formation.
• Demonstrated 91% capacity retention after 800 cycles for Li/LiFePO4 batteries at 1 C.
• Obtained 82% capacity retention after 300 cycles for Li/GPE-FEC/NCM811 cells at 0.5 C.

Conclusions:

• The LiF-rich SEI strategy significantly enhances SEI homogeneity and mechanical stability.
• The developed GPE-FEC system enables high-performance and long-cycle life for high-voltage lithium metal batteries.
• This approach supports the advancement of high-energy-density rechargeable lithium metal batteries.