Regulating cation-solvent interactions in PVDF-based solid-state electrolytes for advanced Li metal batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Poly(vinylidene fluoride) (PVDF)-based solid-state electrolytes (SSEs) show promise for lithium (Li) metal batteries due to mechanical and thermal properties.
• Residual solvents in PVDF-based SSEs cause poor Li metal compatibility, leading to rapid capacity decay.

Purpose of the Study:

• To develop a multifunctional cation-anchor strategy to regulate solvation chemistry in PVDF-based SSEs.
• To enhance the electrochemical performance and stability of Li metal batteries.

Main Methods:

• Utilized a cation-anchor strategy involving N,N-dimethylformamide (DMF) and Zn2+ to alter the Li+ solvation sheath.
• Introduced additional TFSI- anions to form a continuous ion-conducting network.
• Investigated the formation of a LiF-rich solid electrolyte interphase (SEI) layer.

Main Results:

• The cation-anchor strategy induced an anion-reinforced solvation structure, decreasing DMF participation in the Li+ solvation sheath.
• A robust, LiF-rich SEI layer was formed, suppressing interfacial side reactions.
• Achieved stable Li plating/stripping for over 780 hours in Li‖Li symmetrical cells.
• Significantly improved rate capability and cycling stability in Li‖LiFePO4 cells.

Conclusions:

• Regulating solvation chemistry is crucial for enhancing PVDF-based SSEs in Li metal batteries.
• The cation-anchor strategy effectively stabilizes the Li metal anode interface and improves ion transport.
• This approach offers a viable pathway for developing high-performance and durable Li metal batteries.