High capacity battery electrode structures

Abstract

Provided are battery electrode structures that maintain high mass loadings (i.e., large amounts per unit area) of high capacity active materials in the electrodes without deteriorating their cycling performance. These mass loading levels correspond to capacities per electrode unit area that are suitable for commercial electrodes even though the active materials are kept thin and generally below their fracture limits. A battery electrode structure may include multiple template layers. An initial template layer may include nanostructures attached to a substrate and have a controlled density. This initial layer may be formed using a controlled thickness source material layer provided, for example, on a substantially inert substrate. Additional one or more template layers are then formed over the initial layer resulting in a multilayer template structure with specific characteristics, such as a surface area, thickness, and porosity. The multilayer template structure is then coated with a high capacity active material.

1 . (canceled) 
     
     
         2 . An electrode, comprising:
 a substrate;   a first layer of nanostructures rooted to the substrate;   an electrochemically active inner layer coating the first layer, the electrochemically active inner layer having a first porosity; and   an electrochemically active outer layer coating the electrochemically active inner layer, the electrochemically active outer layer having a second porosity different from the first porosity.   
     
     
         3 . The electrode of  claim 2 , wherein the first layer of nanostructures comprises one or more metal silicides. 
     
     
         4 . The electrode of  claim 3 , wherein the one or more metal silicides are selected from the group consisting of nickel silicides, cobalt silicides, copper silicides, silver silicides, chromium silicides, titanium silicides, aluminum silicides, zinc silicides, and iron silicides. 
     
     
         5 . The electrode of  claim 4 , wherein the nickel silicides are selected from the group consisting of Ni 2 Si, NiSi, and NiSi 2 , and combinations thereof. 
     
     
         6 . The electrode of  claim 2 , wherein the electrochemically active inner layer and the electrochemically active inner layer each comprise one or more materials selected from the group consisting of silicon, silicon oxides, silicon oxy-nitrides, tin-containing materials, germanium-containing materials, and carbon-containing materials. 
     
     
         7 . The electrode of  claim 2 , wherein the electrochemically active inner layer comprises amorphous silicon and the electrochemically active outer layer comprises amorphous silicon. 
     
     
         8 . The electrode of  claim 7 , wherein the electrochemically active inner layer and the electrochemically active outer layer have different hydrogen concentrations. 
     
     
         9 . The electrode of  claim 2 , wherein the electrochemically active inner layer and the electrochemically active outer layer have different compositions. 
     
     
         10 . The electrode of  claim 2 , wherein the electrochemically active inner layer and the electrochemically active outer layer have different morphologies. 
     
     
         11 . The electrode of  claim 2 , wherein the inner layer has a lower porosity than the outer layer. 
     
     
         12 . An electrode assembly comprising:
 a conductive substrate for conducting electrical current between an electrode active material and battery terminal; and   an electrode material comprising:   a layer of first nanostructures attached to the conductive substrate, the first nanostructures comprising one or more metal silicides;   a coating of the electrode active material that covers at least a portion of the first nanostructures, the coating comprising an inner layer having a first porosity and an outer layer having a second porosity different from the first porosity,   wherein the first nanostructures provide electronic communication between the electrode active material and conductive substrate.   
     
     
         13 . A method of making an electrode for a battery, comprising the steps of:
 providing nanostructures;   depositing a first silicon layer over the nanostructures using a plasma-enhanced chemical vapor deposition (PECVD) method; and   depositing a second silicon layer over the first silicon layer using a thermal chemical vapor deposition (thermal CVD) method.   
     
     
         14 . The method of  claim 13 , wherein the first silicon layer has a first porosity and the second silicon layer has a second porosity, different from the first porosity. 
     
     
         15 . The method of  claim 13 , wherein the nanostructures comprise one or more metal silicides. 
     
     
         16 . The electrode of  claim 15 , wherein the one or more metal silicides are selected from the group consisting of nickel silicides, cobalt silicides, copper silicides, silver silicides, chromium silicides, titanium silicides, aluminum silicides, zinc silicides, and iron silicides.