Electron Beam Modification of Solid Polymer Electrolytes for Solid-State Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid polymer electrolytes (SPEs) are desirable for lithium metal batteries due to their flexibility.
• However, SPEs typically exhibit low ionic conductivity and poor mechanical properties, hindering their practical application.
• Existing modification methods often involve complex procedures or harsh chemicals.

Purpose of the Study:

• To develop a facile and solvent-free method for enhancing the performance of poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDADMATFSI)-based SPEs.
• To investigate the effects of electron beam (EB) irradiation on the structural and electrochemical properties of SPEs.
• To demonstrate the suitability of EB-irradiated SPEs for high-performance solid-state lithium metal batteries.

Main Methods:

• A solvent-free electron beam (EB) irradiation technique was employed to modify PDADMATFSI-based SPEs.
• The structural changes, including the generation of polar carbonyl groups and crosslinking, were analyzed.
• Electrochemical performance was evaluated using Li||Li symmetric cells and Li||NCM811 full cells, measuring ionic conductivity, transference number, and cycling stability.

Main Results:

• EB irradiation at an optimal dose simultaneously introduced polar carbonyl groups and created a crosslinked polymer network.
• Mechanical strength significantly increased (Young's modulus from 170 to 921 MPa), while ionic conductivity improved (from 4.7 × 10^-4 to 8.2 × 10^-4 S cm^-1).
• Enhanced lithium-ion transport (t_Li⁺ from 0.29 to 0.48) and dielectric properties (from 6.5 to 16.6) were observed, leading to stable cycling of Li||Li symmetric cells for up to 2000 hours and improved performance in Li||NCM811 full cells.

Conclusions:

• Electron beam irradiation is an effective and scalable strategy for fabricating high-performance solid polymer electrolytes.
• The dual modification of introducing polar groups and crosslinking addresses the key limitations of conventional SPEs.
• This approach offers a promising pathway for the development of safer and more efficient solid-state lithium metal batteries.