Carbon nanotube carpet on and grown from copper

Abstract

An anode for an electrochemical cell includes a base layer, predominantly of copper, and an interfacial layer from which extends a carpet of carbon nanotubes. The interfacial layer includes an alloy of the copper and a nanotube catalyst from which the nanotubes nucleate and grow. Lithium metal stored within and between the carbon nanotubes forms an active anode layer.

What is claimed is: 
     
         1 . An electrode comprising:
 a base layer predominantly of copper at a first concentration;   an interfacial layer on the base layer, the interfacial layer including copper at a second concentration and a carbon-nanotube catalyst; and   carbon nanotubes extending from the interfacial layer.   
     
     
         2 . The electrode of  claim 1 , wherein the interfacial layer comprises an alloy of the copper at the second concentration and iron. 
     
     
         3 . The electrode of  claim 2 , wherein the carbon-nanotube catalyst includes precipitates of the iron. 
     
     
         4 . The electrode of  claim 3 , wherein the carbon nanotubes extend from the precipitates of the iron. 
     
     
         5 . The electrode of  claim 1 , wherein the second concentration is lower than the first concentration 
     
     
         6 . The electrode of  claim 1 , the interfacial layer including a catalyst layer opposite the base layer. 
     
     
         7 . The electrode of  claim 6 , wherein the catalyst layer is predominantly of a metal other than copper. 
     
     
         8 . The electrode of  claim 7 , wherein the metal other than copper comprises iron. 
     
     
         9 . The electrode of  claim 1 , wherein the interfacial layer is of a thickness between three and twenty nanometers. 
     
     
         10 . The electrode of  claim 1 , the carbon nanotubes further comprising a second metal. 
     
     
         11 . The electrode of  claim 10 , wherein the second metal comprises aluminum. 
     
     
         12 . The electrode of  claim 10 , wherein the second metal is of a concentration in the carbon nanotubes that varies in proportion to a distance from the interfacial layer. 
     
     
         14 . The electrode of  claim 1 , wherein the carbon-nanotube catalyst is of a metal with an interfacial concentration in the interfacial layer and a lower concentration in the base layer. 
     
     
         15 . The electrode of  claim 1 , wherein the interfacial layer is in ohmic contact with the base layer. 
     
     
         16 . The electrode of  claim 4 , wherein the interfacial layer is in ohmic contact with the carbon nanotubes. 
     
     
         17 . The electrode of  claim 1 , wherein most of the carbon nanotubes are bonded to the interfacial layer by at least one metallic bond. 
     
     
         18 . The electrode of  claim 1 , further comprising a substrate supporting the base layer opposite the interfacial layer. 
     
     
         19 . The electrode of  claim 1 , wherein the copper includes a copper-oxide layer. 
     
     
         20 . The electrode of  claim 1 , wherein the copper includes a copper surface comprising elements other than the copper constituting less than 20 wt. % of the copper surface. 
     
     
         21 . A method of forming nanotubes on an electrode comprising a base layer predominantly of copper, a catalyst layer of a nanotube catalyst on the base layer, and a protective layer over the catalyst layer, the method comprising:
 exposing the protective layer to a nanotube source gas;   heating the electrode, the heating producing an interfacial layer on the base layer, the interfacial layer comprising an alloy of the copper and the nanotube catalyst; and   growing the nanotubes between the interfacial layer and the protective layer.   
     
     
         22 . The method of  claim 21 , the nanotubes lifting the protective layer from the interfacial layer in consequence of the growing. 
     
     
         23 . The method of  claim 21 , further comprising obtaining the electrode by forming the catalyst layer over the base layer and forming the protective layer over the catalyst layer. 
     
     
         24 . The method of  claim 21 , wherein the catalyst layer comprises iron. 
     
     
         25 . The method of  claim 21 , wherein the protective layer comprises an oxide of aluminum. 
     
     
         26 . The method of  claim 21 , further comprising absorbing the protective layer into the nanotubes during the growing. 
     
     
         27 . The method of  claim 21 , wherein the nanotubes are carbon nanotubes.