Electrolytes Containing Ionic Liquids for Improved Safety of Lithium-ion Batteries

Abstract

Ionic liquids are of interest for application in electrolytes of lithium-ion batteries, because of their non-flammability, thermal stability, and non-volatility. Electrolytes containing ionic liquids have therefore been used to improve the safety of lithium-ion cells. Both the liquid electrolyte and the gelled electrolyte, which was composed of 1-ethyl-3-methyl-imidazolium tetrafluoroborate and LiBF 4 , were shown to have good thermal and electrochemical stability and to be applicable for use in lithium-ion cells with Li[Li 1/3 Ti 5/3 ]O 4 as the negative electrode active material. Electrolytes containing a mixture of organic solvents and N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide were also found to exhibit good discharge performance for use in lithium-ion cells and nonflammability for use as an electrolyte. Furthermore, it was found that graphite was able to perform in the electrolyte containing the ionic liquid.

Ultrahigh Power Density and Safety Induced by Ultrathin Electrode Design and Bi-Salt Electrolyte Tailored Lithium Ion Batteries toward Durable 48 V Start/Stop Application

“…In view of the promising potential of ionic liquids in CO 2 absorption, − an ionic liquid-tuned functional electrolyte has been developed to gas capture . Meanwhile, the ionic liquid can significantly improve the cell’s high-temperature stability, − safety performance, power performance, and corrosion inhibition…”

Enabling Sustainable Chemistry with Ionic Liquids and Deep Eutectic Solvents: A Fad or the Future?

“… [176] While the choice of separator plays a critical role in battery safety, the addition of ILs to electrolytes of lithium‐ion batteries attenuates explosion resulting from cell overcharging (Figure 9). The mechanism delineating how ILs mitigate fire and explosion remains unclear, but it is apparent that ILs and DESs exhibit higher flash points, better thermal stability, and less flammability than organic carbonates [177, 178] …”

“…The mechanism delineating how ILs mitigate fire and explosion remains unclear, but it is apparent that ILs and DESs exhibit higher flash points, better thermal stability, and less flammability than organic carbonates. [177,178] Lithium metal anodes significantly increase the energy density of lithium-ion rechargeable batteries. The lithium metal is thermodynamically unstable when in contact with carbonate-based electrolytes, spontaneously reacting to form a Li + conductive solid electrolyte interphase (SEI) layer that prevents further reaction between the anode and the electrolyte.…”

On the concentration polarisation in molten Li salts and borate-based Li ionic liquids

“…28,51,53 Ionic liquid-based electrolytes have been intensively studied as non-flammable liquid electrolytes for enhancing battery safety. [54][55][56][57] However, binary mixtures of aprotic ionic liquids and Li salts dominate the previous reports, and studies on solvent-free molten Li salts or Li ionic liquids containing Li + as the only cations are largely limited because of their intrinsically high melting point. In single-ion conduction, solvent-free molten Li salts or Li ionic liquids can also achieve t Li B 1 under anion-blocking conditions.…”