A promising PMHS/PEO blend polymer electrolyte for all-solid-state lithium ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid-state lithium metal batteries offer higher energy density and safety compared to liquid Li-ion batteries.
• Polymer electrolytes, particularly those based on poly(ethylene oxide) (PEO), are attractive for their flexibility and processability.
• A key challenge is achieving high ionic conductivity in PEO-based electrolytes without compromising mechanical strength.

Purpose of the Study:

• To enhance the ionic conductivity and mechanical properties of poly(ethylene oxide) (PEO)-based solid polymer electrolytes.
• To investigate the potential of incorporating polymethylhydrogen-siloxane (PMHS) into PEO for improved lithium-ion transport.
• To evaluate the performance of the resulting hybrid electrolyte in all-solid-state lithium batteries.

Main Methods:

• Solution casting technique was employed to create hybrid polymer electrolyte membranes.
• Polymethylhydrogen-siloxane (PMHS) was blended with poly(ethylene oxide) (PEO) at varying compositions.
• Electrochemical performance, including ionic conductivity and electrochemical window, was characterized.
• Battery cells (Li/LiFePO4) were assembled and tested to assess performance and stability.

Main Results:

• The hybrid electrolyte membrane with 40% PMHS demonstrated high ionic conductivity (2.0 × 10⁻² S cm⁻¹ at 80 °C).
• The material exhibited a wide electrochemical window (5.2 V), good flexibility, and thermal stability.
• A Li/LiFePO4 battery assembled with this electrolyte delivered a reversible capacity of approximately 140 mA h g⁻¹ (0.1 C) at 60 °C with excellent stability.

Conclusions:

• The incorporation of PMHS effectively optimizes ion transport in PEO-based solid polymer electrolytes.
• The developed hybrid electrolyte shows significant promise for next-generation high energy density all-solid-state lithium-ion batteries.
• This material addresses the challenge of balancing ionic conductivity and mechanical integrity in solid polymer electrolytes.