Organic　electrolyte　is　a　threat　to　the　safe　operation　for　Ni-rich　lithium　ion　batteries　due　to　its　flammability　and　high　voltage　cycle　instability.　Exploring　advanced　battery　electrlytes　with　high　safety　and　high　voltage　cyclability　is　of　great　significance　to　the　development　of　electrical　vehicles　and　grid　energy　storage.　Herein,　a　multi-functional　electrolyte　additive,　ethoxy-(pentafluoro)-cyclotriphosphazene,　for　high-safety　and　high-energy　pouch-type　LiNi0.8Mn0.1Co0.1O2|graphite　(NMC811|Gr)　cells　is　explored.　It　combined　the　structure　of　non-flammable　cyclophosphazene　with　fluorine,　with a　good　electrochemical　compatibility.　The　high　efficiency　of　the　flame　retardant　produced　properties　that　can　not　be　achieved　using　“normal”　fluorine-based　flame　retardants　for　thermal　runaway　inhibition.　Moreover,　the　phosphazene　(C2H5F5N3OP3)-based　electrolyte　(FPEele)　endowed　an　NCM811|Gr　pouch　cell　with　extraordinary　safety　(thermal　runaway　trigger　temperature　increased　by　+41.7 °C,　and　its　highest　temperature　is　decreased　by　─205.7 °C)　and　electrochemical　performance　(4.5 V　high-voltage　cycling,　81.7%　capacity　retention　after　200　cycles).　The　capacity　fading　and　thermal　safety　of　the　battery　are　simultaneously　improved　based　on　the　additive　engineering.　In　fact,　the　phosphazene-based　additive　contained　F,　P,　and　N　atoms,　which　stabilized　the　electrode　interface　and　synergistically　suppressed　combustion　during　battery　failure.　Thus,　such　a　work　can　provide　a　new　ideal　for　designing　a　multi-functional　electrolyte.　©　2025　Wiley-VCH　GmbH.