Polyoxyethylene (PEO)|PEO-Perovskite|PEO Composite Electrolyte for All-Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Composite solid electrolytes (CSEs) combine ceramic and polymer properties for all-solid-state lithium metal batteries (ASSLMBs).
• Poor interfacial contact and undesired reactions between electrodes and solid electrolytes hinder ASSLMB performance.
• Developing stable and high-performance solid electrolytes is crucial for next-generation batteries.

Purpose of the Study:

• To design and fabricate a flexible CSE with improved interfacial compatibility for ASSLMBs.
• To investigate the effect of a PEO|PEO-perovskite|PEO sandwich structure on battery performance.
• To enhance the mechanical strength and ionic conductivity of the CSE.

Main Methods:

• Fabrication of a flexible CSE using polyoxyethylene (PEO) and perovskite (Li$_{0.33}$La$_{0.557}$TiO$_{3}$ - LLTO) via electrospinning.
• Construction of a PEO|PEO-perovskite|PEO sandwich structure to manage interfaces.
• Assembly and testing of Li|CSE|Li symmetric cells and Li|CSE|LiFePO$_{4}$ full cells.

Main Results:

• The PEO|PEO-perovskite|PEO structure effectively prevented direct contact between perovskite and lithium metal, suppressing side reactions.
• The CSE exhibited enhanced mechanical strength and high ionic conductivity (0.16 mS cm$^{-1}$ at 24 °C) due to LLTO nanofiber networks.
• Li|CSE|Li symmetric cells showed stability for over 400 hours, and Li|CSE|LiFePO$_{4}$ full cells delivered 135.0 mAh g$^{-1}$ at 2 C with 79.0% retention after 300 cycles at 60 °C.

Conclusions:

• The integrated sandwich structure is an effective strategy for developing high-performance CSEs for ASSLMBs.
• The proposed CSE design significantly improves interfacial contact, electrochemical stability, and cycling performance.
• This work demonstrates a promising approach for advancing solid-state battery technology.