Electrode Including Nanostructures for Rechargeable Cells

Abstract

A lithium ion battery electrode includes silicon nanowires used for insertion of lithium ions and including a conductivity enhancement, the nanowires growth-rooted to the conductive substrate.

1 . A lithium ion battery electrode comprising:
 a conductive substrate; and   silicon containing nanowires substrate rooted to the conductive substrate and configured for inserting and removing lithium ions during battery cycling maintaining capacity of at least about 1500 mAh/g after at least 20 cycles, the nanowires including a conductivity enhancement component for reducing electrical resistance of the nanowires.   
     
     
         2 . The electrode of  claim 1 , wherein the capacity of silicon containing nanowires is at least about 600 mAh/g after at least 100 cycles. 
     
     
         3 . The electrode of  claim 1 , wherein the nanowires comprise a core and a shell and wherein the material of the core is different from the material of the shell. 
     
     
         4 . The electrode of  claim 3 , wherein the core is the conductivity enhancement component selected from the group consisting of a carbon containing material, a silicide, and a carbide. 
     
     
         5 . The electrode of  claim 1 , wherein the nanowires comprise a core and two or more shells, the material of the core is different from the material of the innermost shell and materials of any two adjacent shells are different. 
     
     
         6 . The electrode of  claim 1 , wherein the nanowires are doped with one or more dopants, which serve as the conductivity enhancement component. 
     
     
         7 . The electrode of  claim 6 , wherein at least one of the one or more dopants is selected from the group consisting of the group III and V elements of the periodic table. 
     
     
         8 . The electrode of  claim 6 , wherein, on average, the concentration of one or more dopants is higher near the outer surfaces of the nanowires than near the centers of the nanowires. 
     
     
         9 . The electrode of  claim 1 , wherein the nanowires have an aspect ratio of at least about ten in a fully discharged state. 
     
     
         10 . The electrode of  claim 1 , wherein the nanowires have an average cross-section dimension of between about 1 nanometer and 300 nanometers in a fully discharged state. 
     
     
         11 . The electrode of  claim 1 , wherein the nanowires have length of at least about 100 micrometer in a fully discharged state. 
     
     
         12 . The electrode of  claim 1 , wherein the nanowires form a layer having porosity of less than about 75 percent before the first cycle. 
     
     
         13 . The electrode of  claim 1 , wherein the average cross-section dimension of the nanowires is such that a fracture limit caused by the electrode swelling is not reached at the maximum charge level. 
     
     
         14 . (canceled) 
     
     
         15 . The electrode of  claim 1 , wherein the nanowires further comprise one or more materials selected from the group consisting of germanium, tin, tin oxide, a tin-silicon alloy, carbon, a carbon-silicon alloy, and titanium oxide. 
     
     
         16 . The electrode of  claim 1 , wherein the conductive substrate comprises a material selected from the group consisting of stainless steel, copper, nickel and titanium. 
     
     
         17 . A lithium ion battery comprising:
 a negative electrode including a conductive substrate and silicon containing nanowires substrate rooted to the conductive substrate and configured for inserting and removing lithium ions during battery cycling maintaining capacity of at least about 1500 mAh/g after at least 20 cycles, the nanowires including a conductivity enhancement component for reducing electrical resistance of the nanowires;   a positive electrode; and   a lithium ion transporting medium positioned between the negative electrode and the positive electrode.   
     
     
         18 . A method of manufacturing an electrode for use in a lithium ion battery, the method comprising:
 providing a conductive substrate; and   forming silicon containing nanowires growth-rooted to the conductive substrate and configured for inserting and removing lithium ions during battery cycling maintaining capacity of at least about 600 mAh/g after at least 100 cycles.   
     
     
         19 . The method of  claim 18 , wherein forming the nanowires comprises:
 forming nanowires without a conductivity enhancement component; and   treating the nanowires to introduce the conductivity enhancement component into the nanowires.   
     
     
         20 . The method of  claim 19 , wherein the conductivity enhancement component comprises one or more materials selected from the group consisting of boron, aluminum, and gallium. 
     
     
         21 . The method of  claim 18 , wherein the conductive substrate is selected from the group consisting of copper, stainless steel, nickel, and titanium. 
     
     
         22 . The electrode of  claim 1 , wherein the substrate-rooted nanowires are growth-rooted. 
     
     
         23 . The electrode of  claim 1 , wherein the substrate-rooted nanowires are attachment rooted.