Enhancing mechanical properties of composite solid electrolyte by ultra-high molecular weight polymers

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Composite solid electrolytes offer advantages for solid-state lithium metal batteries.
• Polymer-in-ceramic electrolytes provide mechanical strength but suffer from poor flexibility and ion transport.
• Existing ceramic-in-polymer electrolytes have limitations in dendrite inhibition.

Purpose of the Study:

• To develop a flexible polymer-in-ceramic solid electrolyte with enhanced mechanical strength and ionic conductivity.
• To overcome the limitations of traditional polymer-in-ceramic electrolytes.
• To improve the performance and safety of solid-state lithium metal batteries.

Main Methods:

• Fabrication of a polymer-in-ceramic film using ultra-high molecular weight polymers and ceramic particles.
• Incorporation of excess lithium salt into the polymer matrix to create a polymer-in-salt structure.
• Characterization of the film's mechanical properties (stiffness) and ionic conductivity.
• Assembly and testing of lithium symmetric cells and LiFePO4 cells.

Main Results:

• The prepared film exhibits high stiffness (10.5 MPa) and flexibility.
• Achieved ionic conductivity of 0.18 mS cm⁻¹.
• Lithium symmetric cells demonstrated stable cycling for over 800 hours.
• LiFePO4 cells delivered a discharge capacity of 147.7 mAh g⁻¹ at 0.1 C with no significant capacity decay over 145 cycles.

Conclusions:

• The developed polymer-in-ceramic electrolyte effectively combines flexibility and mechanical strength.
• The polymer-in-salt structure enhances ionic conductivity, crucial for battery performance.
• This composite electrolyte shows significant potential for safe and high-performance solid-state lithium metal batteries.