High-Performance PEO-Based All-Solid-State Battery Achieved by Li-Conducting High Entropy Oxides.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Solid-state composite electrolytes are crucial for next-generation batteries.
• Polyethylene oxide (PEO)-based electrolytes face challenges in ionic conductivity and operating temperature.
• Developing new active fillers is key to overcoming these limitations.

Purpose of the Study:

• To synthesize and characterize a rock-salt-structured Li-conducting high entropy oxide (HL20).
• To evaluate HL20 as an active filler in PEO-based solid-state composite electrolytes.
• To demonstrate the performance enhancement of all-solid-state batteries using HL20.

Main Methods:

• Synthesis of a Li-conducting high entropy oxide (HL20).
• Analysis of crystal structure using X-ray diffraction and high-resolution transmission electron microscopy.
• Fabrication and electrochemical testing of composite membranes and Li||Li, Li||LiFePO4 batteries.

Main Results:

• HL20 crystallized in the Fm3̅m space group with Li+ ions in MO6 octahedra.
• Composite membrane ionic conductivity reached 3.44 × 10-5 S cm-1 at 30 °C.
• Li||Li symmetric batteries cycled over 1200 h; Li||LiFePO4 full batteries showed 91% capacity retention after 100 cycles.
• Improved activation energy and excellent rate performance at lower temperatures.

Conclusions:

• High entropy oxide (HL20) acts as an effective active filler in PEO-based solid-state electrolytes.
• The composite electrolyte demonstrates promising ionic conductivity and battery performance.
• This research promotes the development of practical, low-temperature all-solid-state batteries.