A Solvent-Induced Solid Polymer Electrolyte with Controllable Polymerization for Low-Temperature Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Solid-state electrolytes are crucial for advanced lithium metal batteries due to their interface compatibility.
• Conventional in situ ring-opening polymerization of 1,3-dioxolane (DOL) leads to long polymer chains, hindering Li+ transport.
• Developing strategies to control polymerization is essential for enhancing electrolyte performance.

Purpose of the Study:

• To regulate the ring-opening polymerization of DOL by introducing N,N-dimethyltrifluoroacetamide (FDMA).
• To improve Li+ transport and interface stability in solid-state electrolytes.
• To enhance the electrochemical performance of lithium metal batteries, particularly at low temperatures.

Main Methods:

• In situ ring-opening polymerization of 1,3-dioxolane (DOL) modified with N,N-dimethyltrifluoroacetamide (FDMA).
• Electrochemical cycling of Li metal batteries with LiFePO4 cathodes.
• Analysis of solid electrolyte interface (SEI) composition and morphology.

Main Results:

• FDMA introduction prevented the formation of long polymer chains during DOL polymerization.
• The resulting solid electrolyte exhibited a stable SEI layer rich in LiF, suppressing dendritic Li growth.
• LiFePO4//Li full batteries demonstrated 83.9% capacity retention after 400 cycles at 5.0 C and a capacity of 137 mAh g-1 at -20 °C.

Conclusions:

• The solvent-induced strategy using FDMA offers a novel approach to designing high-performance solid electrolytes.
• This method enhances interface stability and ionic conductivity, crucial for reliable lithium metal batteries.
• The developed solid electrolyte shows promise for high-temperature resistant battery applications.