Stable and Safe Lithium Metal Batteries with Ni-Rich Cathodes Enabled by a High Efficiency Flame Retardant Additive

A novel electrolyte additive-(trifluoroethoxy)pentafluorocyclotriphosphazene (TFPN) is synthesized and tested as flame retardant additives for lithium metal batteries. Flame test reveals that 5 wt% TFPN addition can enable electrolyte non-flammable. Moreover, it is found that TFPN addition could form a LiF-rich solid electrolyte layer (SEI) on lithium metal and suppress the growth of lithium dendrites. With 5 wt% TFPN added electrolyte, the Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811)/Li full cells show a high reversible capacity and a much improved capacity retention. These results suggest that TFPN may be used as a promising multifunctional additive for lithium metal batteries. These findings may also be useful for the design of other nonaqueous batteries. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.