Reshaping Li⁺-Polyethylene Glycol Interactions to Boost Li⁺ Transport in Solid Polymer Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid polymer electrolytes (SPEs) are vital for solid-state lithium metal batteries (LMBs).
• Polyethylene glycol (PEG)-based polymers facilitate lithium salt dissociation but suffer from strong Li⁺ binding and slow ion transport.
• Efficient Li⁺ transport is critical for high-performance polymer electrolytes.

Purpose of the Study:

• To investigate the use of trimethylamine oxide (TMAO) in SPEs to enhance Li⁺ transport.
• To modify the interaction between Li⁺ and PEG to overcome transport limitations.
• To improve the performance of lithium metal batteries using modified SPEs.

Main Methods:

• Incorporation of TMAO, a biologically derived osmotic agent, into PEG-based SPEs.
• Analysis of Li⁺-PEG interactions and the effect of TMAO on polymer polarization.
• Electrochemical testing of SPEs in lithium metal batteries with LiNi_0.6Co_0.2Mn_0.2O₂ cathodes.

Main Results:

• TMAO effectively coordinates with Li⁺, weakening the Li⁺-PEG binding.
• Enhanced ionic conductivity of 1.07 mS cm^-1 at 25 °C was achieved.
• Improved cycling stability with 96% capacity retention over 300 cycles in LMBs.

Conclusions:

• TMAO is a promising additive for enhancing Li⁺ transport in SPEs.
• Modulating Li⁺-polymer interactions is a viable strategy for advancing solid-state battery technology.
• This approach offers a new perspective for developing high-performance polymer electrolytes for energy storage applications.