US Patent 9755241 Alkali metal secondary battery containing a dendrite-intercepting layer

A rechargeable alkali metal battery comprising: (A) an anode comprising an alkali metal layer and a dendrite penetration-resistant layer composed of multiple graphene sheets or platelets or exfoliated graphite flakes that are chemically bonded by a lithium- or sodium-containing species to form an integral layer that prevents dendrite penetration through the integral layer, wherein the lithium-containing species is selected from Li2CO3, Li2O, Li2C2O4, LiOH, LiX, ROCO2Li, HCOLi, ROLi, (ROCO2Li)2, (CH2OCO2Li)2, Li2S, LixSOy, Na2CO3, Na2O, Na2C2O4, NaOH, NaX, 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; (B) a cathode comprising a cathode layer; and (C) a separator and electrolyte component in contact with the anode and the cathode; wherein the dendrite penetration-resistant layer is disposed between the alkali metal layer and the separator.