Intermediate layers for electrode fabrication

Abstract

Provided are novel electrodes for use in lithium ion batteries. An electrode includes one or more intermediate layers positioned between a substrate and an electrochemically active material. Intermediate layers may be made from chromium, titanium, tantalum, tungsten, nickel, molybdenum, lithium, as well as other materials and their combinations. An intermediate layer may protect the substrate, help to redistribute catalyst during deposition of the electrochemically active material, improve adhesion between the active material and substrate, and other purposes. In certain embodiments, an active material includes one or more high capacity active materials, such as silicon, tin, and germanium. These materials tend to swell during cycling and may loose mechanical and/or electrical connection to the substrate. A flexible intermediate layer may compensate for swelling and provide a robust adhesion interface. Provided also are novel methods of fabricating electrodes containing one or more intermediate layers.

1 . An electrode for use in a lithium ion battery, the electrode comprising:
 a substrate;   one or more intermediate layers formed on the substrate; and   an electrochemically active material in the form of nanostructures formed over the one or more intermediate layers and operable for inserting and removing lithium ions during battery cycling,   wherein the electrochemically active material is in electrical communication with the substrate.   
     
     
         2 . The electrode of  claim 1 , wherein the substrate comprises one or more materials selected from the group consisting of copper, nickel, aluminum, stainless steel, and titanium. 
     
     
         3 . The electrode of  claim 1 , wherein the active material comprises one or more materials selected from the group consisting of silicon, tin, germanium, a silicon-germanium combination, tin oxide, silicon oxycarbide (SiOC), and their compounds. 
     
     
         4 . The electrode of  claim 3 , wherein the active material comprises silicides. 
     
     
         5 . The electrode of  claim 4 , wherein the active material comprises nickel silicides. 
     
     
         6 . The electrode of  claim 1 , wherein at least one of the one or more intermediate layers comprises one or more elements selected from the group consisting of chromium, titanium, tantalum, tungsten, nickel, molybdenum, iron, and lithium. 
     
     
         7 . The electrode of  claim 1 , wherein a thickness of the one or more intermediate layers is between about 1 nanometer and 2000 nanometers. 
     
     
         8 . The electrode of  claim 1 , wherein an electrical resistance over a unit of surface area of the one or more intermediate layers is less than about 1 Ohm-centimeter squared. 
     
     
         9 . The electrode of  claim 1 , wherein the nanostructures comprise substrate-rooted nanowires. 
     
     
         10 . The electrode of  claim 1 , wherein the one or more intermediate layers comprise a diffusion barrier layer configured to shield the substrate during formation of the electrochemically active material. 
     
     
         11 . The electrode of  claim 1 , wherein the one or more intermediate layers comprise an adhesion layer configured to maintain mechanical connection between the substrate and the electrochemically active material during battery cycling. 
     
     
         12 . The electrode of  claim 1 , wherein the one or more intermediate layers has a surface tension configured for depositing a catalyst layer and forming catalyst islands from the catalyst layer during formation of the active material. 
     
     
         13 . The electrode of  claim 1 , wherein the one or more intermediate layers are configured to separate catalyst particles from a carrier fluid. 
     
     
         14 . The electrode of  claim 1 , wherein the one or more intermediate layers comprise an exposed surface having a roughness that enables distribution of a catalyst in discreet patches. 
     
     
         15 . The electrode of  claim 1 , wherein the one or more intermediate layers comprise a surface condition providing nucleation sites for facilitating deposition of the electrochemically active material. 
     
     
         16 . A method of manufacturing a battery electrode for use in a lithium ion battery, the method comprising:
 receiving a substrate for the battery electrode;   forming a conductive intermediate layers on the substrate; and   depositing an electrochemically active material comprising nanowires on the one or more intermediate layers, wherein the electrochemically active material is configured for inserting and removing lithium ions during battery cycling.   
     
     
         17 . The method of  claim 16 , wherein depositing the electrochemically active material comprises a vapor-solid-solid chemical (VLS) vapor deposition (CVD) process. 
     
     
         18 . The method as in one of  claims 16 , wherein depositing the active material includes depositing a catalyst on the one or more intermediate layers. 
     
     
         19 . The method as in one of  claims 16 , wherein the formation of the conductive intermediate layers comprises depositing at least two intermediate layers. 
     
     
         20 . The method as in one of  claims 16 , wherein the intermediate layer comprises a surface condition that enhances nucleation of the active material during the deposition of the active material.