Flame retardants can reduce the fire risk of the liquid carbonate-based electrolytes in lithium-ion batteries. Two PIN flame retardants (phenoxycylophosphazene, melamine phosphate) and tris (2-chloropropyl) phosphate were tested in a battery electrolyte consisting of 1M LiPF6 dissolved in 1:1:1 ethylene carbonate – dimethyl carbonate – diethyl carbonate. Both of the PIN FRs, at 5 – 15% loading, reduce the combustion rate of the electrolyte and the flame height, but do not reduce the flame temperature. The chlorinated phosphorus FR reduces both the combustion rate and the flame temperature. Higher FR loadings offer greater reductions in fire risk. The lithium salt in the electrolyte accentuates fire risk. The authors conclude that “composite” flame retardants combining several different elements, and so different action mechanisms, are more effective.
“Comparative studies on the combustion characters of the lithium-ion battery electrolytes with composite flame-retardant additives”, M. Chen et al., J. Energy Storage 2021 https://doi.org/10.1016/j.est.2021.103642