Solid Polymer Electrolyte Reinforced with a Li_1.3Al_0.3Ti_1.7(PO₄)₃-Coated Separator for All-Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Poly(ethylene oxide) (PEO)-based solid-state electrolytes (SSEs) offer potential for high energy density and safety in lithium batteries.
• However, PEO-based SSEs face challenges including low oxidation stability, poor room-temperature ionic conductivity, and inadequate mechanical properties, hindering large-scale applications.

Purpose of the Study:

• To design and fabricate a PEO-based ceramic-polymer (PCP) composite SSE with improved mechanical and electrochemical properties.
• To investigate the ability of the PCP membrane to suppress lithium dendrite growth and enhance the stability of the lithium anode interface.

Main Methods:

• A composite SSE was prepared by filling a porous Li$_{1.3}$Al$_{0.3}$Ti$_{1.7}$(PO$_{4}$)$_{3}$ (LATP)-coated polyethylene (PE) separator with PEO/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solution.
• The electrochemical performance was evaluated using Li/PCP/Li symmetric cells and Li/PCP/LiFePO$_{4}$ all-solid-state batteries, focusing on lithium deposition behavior and cycling stability at 60 °C.

Main Results:

• The PCP membrane demonstrated effective suppression of lithium dendrite growth, evidenced by flat lithium deposition.
• A stable interface layer, a mixed ionic/electronic conducting interphase (MCI) intertwined with a solid electrolyte interface (SEI), formed between the PCP membrane and the lithium anode.
• The Li/PCP/Li symmetric cell exhibited excellent cycling stability for over 2000 hours at 0.2 mA cm$^{-2}$.
• The Li/PCP/LiFePO$_{4}$ all-solid-state battery maintained a stable cycling performance of 160 mAh g$^{-1}$ at 0.2C after 200 cycles.

Conclusions:

• The developed PCP composite SSE, utilizing an LATP-coated PE separator, offers robust mechanical properties and processable flexibility.
• The membrane effectively prevents short-circuiting by suppressing lithium dendrites and enhances electrolyte/anode interface stability.
• The facile fabrication method suggests the PCP membrane's potential for practical applications in solid-state lithium batteries.