The　uncontrollable　growth　of　lithium　dendrites　and　the　flammability　of　electrolytes　are　the　direct　impediments　to　the　commercial　application　of　high-energy-density　lithium　metal　batteries　(LMBs).　Herein,　this　study　presents　a　novel　approach　that　combines　microencapsulation　and　electrospinning　technologies　to　develop　a　multifunctional　composite　separator　(P@AS)　for　improving　the　electrochemical　performance　and　safety　performance　of　LMBs.　The　P@AS　separator　forms　a　dense　charcoal　layer　through　the　condensed-phase　flame　retardant　mechanism　causing　the　internal　separator　to　suffocate　from　lack　of　oxygen.　Furthermore,　it　incorporates　a　triple　strategy　promoting　the　uniform　flow　of　lithium　ions,　facilitating　the　formation　of　a　highly　ion-conducting　solid　electrolyte　interface　(SEI),　and　encouraging　flattened　lithium　deposition　with　active　SiO2　seed　points,　considerably　suppressing　lithium　dendrites　growth.　The　high　Coulombic　efficiency　of　95.27%　is　achieved　in　Li–Cu　cells　with　additive-free　carbonate　electrolyte.　Additionally,　stable　cycling　performance　is　also　maintained　with　a　capacity　retention　rate　of　93.56%　after　300　cycles　in　LFP//Li　cells.　Importantly,　utilizing　P@AS　separator　delays　the　ignition　of　pouch　batteries　under　continuous　external　heating　by　138 s,　causing　a　remarkable　reduction　in　peak　heat　release　rate　and　total　heat　release　by　23.85%　and　27.61%,　respectively,　substantially　improving　the　fire　safety　of　LMBs.　©　2024　Wiley-VCH　GmbH.