Polyfluorinated crosslinker-based solid polymer electrolytes for long-cycling 4.5 V lithium metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are crucial for lithium metal batteries (LMBs) due to their ability to form intimate electrode contacts.
• Conventional SPEs possess limited electrochemical stability windows (ESWs) due to oxidizable polar groups, hindering high-voltage operation.
• High-voltage operation is essential for increasing the specific capacity and energy density of LMBs.

Purpose of the Study:

• To develop robust SPEs with enhanced oxidation resistance for high-voltage LMBs.
• To overcome the ESW limitations of traditional SPEs.
• To enable long-cycling performance in high-voltage lithium metal batteries.

Main Methods:

• Incorporation of a polyfluorinated crosslinker into the SPE structure.
• Utilizing the inductive electron-withdrawing effect of polyfluorinated segments to improve oxidation resistance.
• Fabrication and testing of Li|SPE|LiNi0.5Co0.2Mn0.3O2 cells.

Main Results:

• The polyfluorinated crosslinked SPE demonstrated a significantly widened ESW.
• The developed SPE enabled high-voltage operation up to 4.5 V.
• The Li|SPE|LiNi0.5Co0.2Mn0.3O2 cell achieved a high discharge specific capacity of ~164.19 mAh g-1 at 0.5 C.
• Excellent capacity retention of ~90% was observed after 200 cycles.

Conclusions:

• Polyfluorinated crosslinking is an effective strategy to enhance the oxidation resistance of SPEs.
• This approach facilitates the development of SPEs for long-cycling, high-voltage lithium metal batteries.
• The findings open new avenues for designing advanced electrolytes for next-generation energy storage devices.