All-Solid-State Lithium Metal Batteries with Microdomain-Regulated Polycationic Solid Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are crucial for developing high-energy and high-safety solid-state lithium metal batteries (LMBs).
• Achieving stable and fast-charging high-voltage LMBs requires electrolytes with high ionic conductivity, good Li+ transference, and wide electrochemical windows.
• Traditional SPEs often face challenges in balancing these properties for demanding battery applications.

Purpose of the Study:

• To design and synthesize a novel polycationic solid electrolyte (PCSE) for advanced solid-state lithium metal batteries.
• To leverage the unique properties of polycationic and fluorinated microdomains for enhanced electrolyte performance.
• To demonstrate the efficacy of the PCSE in enabling stable and fast-charging high-voltage LMBs.

Main Methods:

• Development of a polycationic solid electrolyte (PCSE) incorporating a fluorinated microdomain.
• Utilizing the anion trapping (FMAT) effect for localized solvation and restricted anion mobility.
• In situ thermal polymerization of the electrolyte within assembled Li|LiNi0.8Co0.1Mn0.1O2 cells.

Main Results:

• The PCSE achieved a high ionic conductivity of 1.4 mS cm-1 and a Li+ transference number of 0.50.
• A wide electrochemical window of approximately 5.5 V was observed at 25 °C.
• Li|LiNi0.8Co0.1Mn0.1O2 cells demonstrated ultra-stable cycling with 98.1% capacity retention after 500 cycles at 0.2 C.

Conclusions:

• The developed PCSE offers a promising strategy for creating stable and high-performance solid-state lithium metal batteries.
• The molecular design, combining polycationic stability with fluorinated anion trapping, addresses key challenges in SPE development.
• This approach paves the way for next-generation high-energy, long-life, ambient-temperature solid-state LMBs.