LiTDI (lithium 2-trifluoromethyl-4,5-dicyanoimidazolide) is used as an electrolyte additive in lithium-ion batteries for several significant benefits:
Benefits of Using LiTDI as an Electrolyte Additive
1. Stabilization of the Solid Electrolyte Interface (SEI):
LiTDI helps stabilize the SEI layer on the anode, which is critical for battery longevity and performance. A stable SEI prevents continuous electrolyte decomposition and capacity loss.
2. Scavenging of Harmful Impurities (HF and Water):
LiTDI interacts with water and hydrofluoric acid (HF), which are degradation products of the common lithium salt LiPF6. By trapping water molecules through hydrogen bonding and reacting with HF, LiTDI suppresses harmful side reactions such as electrolyte solvent degradation and parasitic cathode reactions. This interaction improves electrolyte purity and stability, thereby extending battery life.
3. Passivation of Aluminum Current Collectors:
In high-voltage lithium-ion cells, LiTDI prevents the anodic dissolution and pitting corrosion of aluminum current collectors. This corrosion inhibition contributes to safer and more durable high-voltage battery operation.
4. Enhanced Battery Lifetime and Fast-Charging Performance:
Adding just about 1% LiTDI to the electrolyte significantly improves battery lifetime by stabilizing the electrolyte and SEI. It also reduces cell impedance, which enhances fast charging and discharging capabilities. LiTDI enables stable cycling at elevated temperatures (above 45°C), which is beneficial in practical applications.
5. Compatibility with Various Anode Materials:
LiTDI extends battery life not only for traditional graphite anodes but also for silicon-based anodes, which typically suffer from more severe volume expansion and degradation. This versatility makes LiTDI valuable across different battery chemistries.
6. Prevention of LiTDI Reduction by Other Additives:
While LiTDI can form a thick and resistive SEI if directly reduced, this can be prevented by adding other electrolyte additives like fluoroethylene carbonate (FEC), vinylene carbonate (VC), or lithium bis(oxalato)borate (LiBOB), which preferentially reduce to form a protective SEI, allowing LiTDI to perform its beneficial roles without increasing impedance.
In summary, LiTDI as an electrolyte additive improves lithium-ion battery performance by:
- Stabilizing the solid electrolyte interface
- Scavenging water and HF impurities to prevent degradation
- Protecting aluminum current collectors from corrosion
- Enhancing battery life and fast-charging ability
- Enabling operation at high temperatures
- Supporting various anode chemistries including silicon-based anodes
- Working synergistically with other additives to form an optimal SEI
These combined effects make LiTDI a valuable additive for improving safety, durability, and performance of lithium-ion batteries.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-are-the-benefits-of-using-litdi-as-an-electrolyte-additive/
