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Tetrahydrofuran (THF) Breakthrough in New Energy Battery Electrolytes: Balancing Low-Temperature Performance and Safety ——Optimizing Ionic Conductivity Across Wide Temperature Ranges
Created on 03.19
1. The Low-Temperature Challenge in Lithium-Ion Batteries
Lithium-ion batteries face severe performance degradation in extreme temperatures. Below -20°C, traditional carbonate-based electrolytes suffer from sluggish ion transport, high desolvation energy barriers (~0.8 eV), and unstable solid-electrolyte interphases (SEI)
1. These limitations restrict applications in polar expeditions, electric vehicles in cold climates, and aerospace technologies.
Tetrahydrofuran (THF), a cyclic ether solvent, has emerged as a game-changer due to its low viscosity (0.55 cP at 25°C) and weak Li⁺-solvent interactions, enabling ultrafast ion migration even at subzero temperatures
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2. THF-Driven Electrolyte Design Innovations
2.1 Solvent Engineering: Disrupting Aggregated Ion Clusters
The THF-MTBE (methyl tert-butyl ether) hybrid solvent system (e.g., 0.25THMT electrolyte) effectively disrupts large ion aggregates (AGGs) that dominate conventional electrolytes
2. By forming contact ion pairs (CIPs), this system:
- Reduces ionic migration resistance, increasing ionic conductivity from 0.27 to 4.21 mS/cm
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- Lowers the Li⁺ desolvation energy barrier, as evidenced by Arrhenius activation energy (Ea,ct) reduction
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2.2 Wide-Temperature Performance Validation
- At -40°C69% of room-temperature capacity
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- Fast-Charging Capability
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3. Mechanistic Insights: Why THF Excels in Cryogenic Conditions
3.1 Solvation Structure Modulation
THF’s low donor number (DN=20.0) weakens Li⁺-solvent binding, promoting anion (e.g., TFSI⁻) participation in solvation shells. This facilitates:
- Inorganic-Rich SEI Formation65% LiF/Li₂O
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- Suppressed Solvent Co-Intercalation
3.2 Thermal Resilience and Safety
- Flame Retardancy
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- SEI Stability Under Thermal Stress
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4. Synergistic Safety Strategies
4.1 Additive Optimization
- Fluoroethylene Carbonate (FEC)
- Lithium Nitrate (LiNO₃)
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4.2 Industrial Scalability Considerations
- Cost-Effectiveness
- Compatibility with High-Ni Cathodes
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5. Future Directions
5.1 Beyond Lithium-Ion: Multibattery Compatibility
THF’s design principles show promise for:
- Sodium-Ion Batteries
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- All-Solid-State Batteries
5.2 Sustainability Integration
- Closed-Loop Recycling
- Bio-THF Production
Conclusion
THF-based electrolytes represent a paradigm shift in balancing ultralow-temperature operation and intrinsic safety for next-gen batteries. By leveraging its unique solvation chemistry and coupling with advanced additives, THF unlocks:
- Wide-Temperature Adaptability
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- Scalable Manufacturing
As research progresses toward multivalent-ion systems and bio-sourced THF, this solvent will play a pivotal role in realizing energy-dense, fast-charging batteries for a carbon-neutral future.
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