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Breaking Voltage Limitations: Triethyl Phosphate-Engineered PVDF-Based Electrolytes with Dual-Interphase
Lin Yang1,2, Youqi Chu3, Yitian Feng1,2
1Shenzhen Key Laboratory of Advanced Energy Storage, Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Journal of the American Chemical Society
|July 11, 2025
Summary
This study enhances solid-state lithium metal batteries using triethyl phosphate (TEP) solvent, expanding the voltage window to 4.8 V. This enables stable operation at 4.7 V, improving battery performance and longevity.
Area of Science:
- Materials Science
- Electrochemistry
- Computational Chemistry
Background:
- Solid-state lithium metal batteries (SSLMBs) face voltage limitations with conventional electrolytes.
- Dimethylformamide (DMF)-processed poly(vinylidene fluoride) quasi-solid-state polymer electrolytes (SPEs) have intrinsic voltage constraints.
Purpose of the Study:
- To overcome voltage limitations in SPEs for practical SSLMBs.
- To engineer a high-band-gap solvent for enhanced electrochemical stability.
Main Methods:
- Molecular engineering using triethyl phosphate (TEP) as a high-band-gap solvent.
- First-principles calculations to determine TEP's orbital configuration and electrochemical window.
- Fabrication and testing of Li||NCM811 cells with optimized SPEs.
Main Results:
- TEP expands the electrochemical window to 4.8 V (0.5 V enhancement over DMF).
- Optimized SPEs enable stable Li||NCM811 cell operation up to 4.7 V.
- Excellent long-term cycling stability achieved: 88.2% retention at 4.2 V (1800 cycles) and 86.8% at 4.5 V (900 cycles).
- Stable cycling for 500 cycles at 4.7 V.
- Dual interfacial stabilization: Li3PO4-rich cathode interphase and Li2O-dominated anode interphase.
Conclusions:
- Molecular design of SPEs with high-band-gap solvents like TEP is a viable strategy for 4.7 V-class SSLMBs.
- Interfacial stabilization mechanisms are key to achieving high-voltage performance and long-term cyclability.
- This work provides a pathway for developing next-generation high-voltage SSLMBs.
