Ambient Cationic Activation-Radical Synergy Yields High-Performance Polymer Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Conventional in situ thermal polymerization for electrolytes requires high temperatures, leading to depleted monomers and salts.
• This depletion hinders ionic transport and creates unstable solid-electrolyte interphases (SEI) in lithium metal batteries (LMBs).

Purpose of the Study:

• To develop a novel polymerization strategy for gel polymer electrolytes (GPEs) that operates at room temperature.
• To improve ionic conductivity and SEI stability in LMBs.

Main Methods:

• Proposed a cationic activation-radical synergy (CIP) strategy using PF6- derived Lewis acidic species to activate vinylene carbonate (VC).
• Utilized theoretical calculations and in situ spectroscopic analyses to understand the polymerization mechanism.
• Fabricated and tested GPEs in LMBs.

Main Results:

• Achieved controlled polymerization at room temperature via a cationic-induced pathway, distinct from thermal-initiated processes.
• The GPE exhibited enhanced ionic transport with a transference number of 0.78 and conductivity of 6.49 × 10-3 S cm-1.
• LMBs with the GPE showed a dense, inorganic-rich SEI, enabling over 2000 hours of stable lithium plating/stripping and 1200 cycles at 0.5 C.

Conclusions:

• The CIP strategy offers a distinct, low-temperature polymerization mechanism for GPEs.
• The developed GPE significantly enhances ionic transport and SEI stability in LMBs.
• This approach demonstrates potential for high-performance and stable lithium metal batteries.