Macroscopically Ordered Piezo-Potential in All-Polymetric Solid Electrolytes Responding to Li Anode Volume Changes...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Solid-state polymer electrolytes (SPEs) improve lithium-metal battery safety but struggle with dendrite formation due to anode volume changes.
• Lithium dendrites are a major safety and performance concern in next-generation batteries.

Purpose of the Study:

• To develop a novel strategy for inhibiting lithium dendrite growth in solid-state batteries.
• To investigate the role of directional electric fields generated by piezoelectric polymers in controlling lithium deposition.

Main Methods:

• Fabrication of piezoelectric poly(vinylidene-co-trifluoroethylene) [P(VDF-TrFE)] nanofiber interphases with aligned dipoles.
• Characterization of the generated electric fields and their effect on Li+ migration and deposition.
• Testing of symmetric Li cells and LiNi0.8Co0.1Mn0.1O2 (NCM811)//Li full cells for stability and cycling performance.

Main Results:

• The piezoelectric P(VDF-TrFE) interphase generated a directional electric field that steered Li+ deposition from dendrite tips to planar regions.
• Achieved high ionic conductivity (5.0 × 10-4 S cm-1) and Li+ transference number (0.40).
• Symmetric Li cells demonstrated 3000 h stability, and full cells retained 96% capacity after 400 cycles. Reversing the field direction negated these improvements.

Conclusions:

• Directionally engineered piezoelectric fields in polymer interphases are crucial for effective dendrite inhibition.
• This approach offers a new pathway for enhancing the safety and performance of lithium-metal solid-state batteries.
• The study highlights the importance of controlling the orientation of piezoelectric fields for battery applications.