In Situ-Polymerized High-Entropy-Driven Solid Polymer Electrolyte for Safer Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state batteries offer enhanced safety and energy density.
• In situ polymerization is promising for scalable solid-state battery production.
• Current solid polymer electrolytes lack sufficient oxidation stability for high-voltage applications.

Purpose of the Study:

• To design and synthesize novel in situ-polymerized high-entropy-driven solid polymer electrolytes.
• To enhance the oxidation stability and electrochemical performance of solid polymer electrolytes for high-voltage solid-state lithium metal batteries.
• To demonstrate the feasibility of these electrolytes in practical battery devices.

Main Methods:

• Synthesis of high-entropy solid polymer electrolytes using five cyclic ether monomers via in situ polymerization.
• Electrochemical characterization including cyclic voltammetry, impedance spectroscopy, and long-term cycling tests.
• Fabrication and testing of solid-state lithium metal pouch cells with high-voltage cathodes.

Main Results:

• Achieved a voltage tolerance of 5.2 V due to a disordered alkyl chain and weakened solvation.
• Formation of a LiBr-rich organic-inorganic hybrid passivation layer improved cycling stability (>1000 h).
• Demonstrated excellent rate performance (100% state of charge in 7.5 min) and long-term cycling (>700 cycles) with high-voltage cathodes.
• Fabricated a pouch cell with high energy density (287.13 W h kg⁻¹) and excellent capacity retention (98.67% over 100 cycles).

Conclusions:

• The developed high-entropy solid polymer electrolytes significantly enhance oxidation stability and electrochemical performance.
• This approach offers a viable strategy for realizing safer, high-voltage solid-state lithium metal batteries.
• The findings pave the way for the large-scale manufacturing of advanced solid-state batteries.