Polymer　dielectrics　play　an　important　role　in　modern　electric　power　systems　because　of　their　ultrahigh　power　density,　low　cost,　and　lightweight.　Current　high-k　polymers　represented　by　poly(vinylidene　fluoride)　(PVDF)　based　ferroelectric　polymers　suffer　from　the　high　energy　loss　as　well　as　the　low　temperature　level.　To　overcome　the　conduction　induced　high　loss,　in　present　work,　a　BN　thin　layer　fabricated　from　an　oil-water　self-assembly　method　is　transferred　on　poly(vinylidene　fluoride-chlorotrifluoroethyelen)　(P(VDF-CTFE))　films.　The　BN　layer　with　high　bandgap　may　significantly　depress　the　dielectric　loss　of　polymer　films,　and　reduce　the　charge　injection　in　the　films　at　both　elevated　temperature　and　electric　field.　That　is　responsible　for　the　dramatically　increased　breakdown　strength,　energy　density,　discharge　efficiency　and　even　temperature　level　of　P(VDF-CTFE).　The　optimized　sample　(c.a.　BP-3)　possesses　a　high　energy　density　of　12.95　J/cm3　at　525　MV/m　at　ambient　temperature.　At　80　°C,　BP-3　sample　has　an　energy　density　of　6.38　J/cm3,　which　is　nearly　8　times　that　of　pristine　P(VDF-CTFE)　(0.78　J/cm3).　This　work　offers　a　promising　strategy　to　improve　the　breakdown　strength　and　the　dielectric　performance　of　polymeric　dielectrics.　©　2020　Elsevier　B.V.