In Situ-Initiated Poly-1,3-dioxolane Gel Electrolyte for High-Voltage Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Developing high-energy-density lithium metal batteries for low-temperature operation requires advanced electrolytes addressing high-voltage compatibility and efficient lithium-ion de-solvation.
• Gel polymer electrolytes (GPEs) combining solid polymer electrolyte (SPE) and liquid electrolyte (LE) advantages are actively researched.

Purpose of the Study:

• To introduce a new gel polymer electrolyte (P-DOL) for low-temperature, high-energy lithium metal batteries.
• To evaluate the electrochemical performance and stability of P-DOL in Li‖LiCoO2 and Li‖NCM811 cells at various temperatures.

Main Methods:

• Synthesized P-DOL via lithium difluoro(oxalate)borate (LiDFOB)-initiated polymerization of 1,3-dioxolane (DOL).
• Characterized ionic conductivity and oxidation potential of P-DOL.
• Tested Li‖LiCoO2 cells at room temperature and Li‖NCM811 cells at -20 °C.

Main Results:

• P-DOL exhibited ionic conductivity of 1.12 × 10⁻⁴ S cm⁻¹ at -20 °C and an oxidation potential of 4.8 V.
• Li‖LiCoO2 cells showed stable cycling at 4.3 V with 86.4% capacity retention after 50 cycles.
• Li‖NCM811 cells operated at -20 °C for 120 cycles with 88.4% capacity retention, attributed to a robust B- and F-rich cathode interface layer (CEI).

Conclusions:

• The developed P-DOL facilitates high-performance lithium metal batteries at low temperatures.
• The robust CEI formation is key to the electrolyte's high-voltage compatibility and stability.
• This work paves the way for practical, all-climate lithium metal battery applications.