Electrochemical Behavior of Nonflammable Organo-Fluorine Compounds for Lithium Ion Batteries

Abstract

The electrochemical behavior of organo-fluorine compounds with antioxidation ability has been investigated. Oxidation currents of fluorine-compound-containing ethylene carbonate (EC)/diethyl carbonate (DEC) solutions were much smaller than those of EC/DEC and EC/DEC/propylene carbonate (PC) at potentials higher than 6 V vs Li/Li+ . Electrochemical reduction of fluorine compounds started at ca. 2 V vs Li/Li+ , higher than those for EC, DEC, and PC. However the first coulombic efficiencies for natural graphite electrodes in fluorine-compound-containing EC/DEC mixtures were nearly the same as those in EC/DEC without an increase in irreversible capacities. Furthermore the first coulombic efficiencies in fluorine-compound-containing EC/DEC/PC mixtures were much larger than those in EC/DEC/PC itself. The results show that the fluorine compounds used in the present study can be used as nonflammable solvents for lithium ion batteries.

Nonaqueous Electrolytes with Advances in Solvents

“…In addition, when Tafel polarization measurements were performed, the novel electrolytes resulted in the least amount of electrode polarization and the highest limiting current densities implying facile lithium intercalation/de-intercalation kinetics. Similar results were reported on bis(2,2,3,3-tetrafl uoropropyl) carbonate and bis(2,2,3,3,3-pentafl uoropropyl) carbonate in Scheme 2.9 [ 31 ]. …”

Electrolytes for Lithium and Lithium-Ion Batteries

“…2. These molecules have traditionally been used in specialized applications such as coolants and supercapacitors, and their use in Li-ion batteries is relatively new [5,6,74,78]. Regardless, these molecules have shown increased stability toward oxidation, better thermal stability, and low flammability.…”

“…Thus, fluorinated carbonates, especially linear carbonates, are excellent candidates for the low-temperature Li-ion batteries for space and deep-sea missions. Last but not least, the low-flammability to non-flammability of fluorinated compounds could potentially improve the safety of Li-ion batteries [5,6].…”

High Performance Lithium-Ion Batteries Using Fluorinated Compounds

“…Fluorinated organics may be good candidates for electrolyte solvents. Fluorinated cyclic and linear carbonate compounds possess desirable physical properties as lithium-ion battery electrolyte, which are imparted by the presence of the fluorine substituents, such as low melting point, increased oxidation stability, and less flammability [48,49]. In fact, fluorinated cyclic carbonate has been reported as a cosolvent by McMillan [50] and Nanbu [51], and as an SEI formation additive for graphite [52] and silicon [53] anodes.…”

“…A series of fluorinated linear carbonates was designed and synthesized by Smart et al [54] at NASA's Jet Propulsion Laboratory as new electrolyte components to improve the low temperature performance of the lithium-ion battery for deep space applications. Achiha et al [49,55] and Arai [56] separately reported the fluorinated carbonates and fluorinated ethers as nonflammable electrolytes or as new solvents for nonaqueous lithium-ion battery electrolytes.…”