A dendrite penetration-resistant layer for a rechargeable alkali metal battery, comprising an amorphous carbon or polymeric carbon matrix, an optional carbon or graphite reinforcement phase dispersed in this matrix, and a lithium- or sodium-containing species that are chemically bonded to the matrix and/or the optional carbon or graphite reinforcement phase to form an integral layer that prevents dendrite penetration through this integral layer in the alkali metal battery, wherein the lithium- or sodium-containing species is selected from Li2CO3, Li2O, Li2C2O4, LiOH, LiX, ROCO2Li, HCOLi, ROLi, (ROCO2Li)2, (CH2OCO2Li)2, Li2S, LixSOy, Na2CO3, Na2O, Na2C2O4, NaOH, NaiX, ROCO2Na, HCONa, RONa, (ROCO2Na)2, (CH2OCO2Na)2, Na2S, NaxSOy, or a combination thereof, wherein X=F, Cl, I, or Br, R= a hydrocarbon group, x=0-1, y=1-4; and wherein the lithium- or sodium-containing species is derived from an electrochemical decomposition reaction.