Liquid electrolytes flame retardants

We have reviewed safety improvements of organic electrolytes by adding flame retardants, and ILs have also been discussed. A more radical solution would be replacing liquid organic electrolytes with solvent-free lithium conductive-membranes reviewed in [196,197]. The most promising options have been briefly reviewed in [198], in particular membranes based on homopolymers, such as poly(ethylene oxide) hosting a lithium salt. However, the conductivity of these polymers is still too low to make them suitable to batteries operating at ambient temperature [199]. 

Other than the aforementioned compounds, flame retardant additives with other stmctures could be further explored. Many ionic liquids are known to be non-flammable, and ionic liquids could also be used as additives to lower the flammability of the electrolyte [12, 30]. Nitrogen-containing heterocyclic compounds with fluorinated substitutions have also been reported as new flame retardant additives [61,62]. Finally, a silane compound, methyl phenyl bismethoxydiethoxysilane, has been reported to serve as both the SEI formation additive and flame retardant additive [79]. 

When lithium cells are subjected to various abuses, thermal runaway can occur which causes safety hazards. This is a huge issue, especially in the use of these batteries in electric cars and in some aircrafts. A number of flame-retarded or nonflammable electrolytes are being developed by employing additives [1] or ionic liquids [2]. 

---