Composite structures containing high capacity porous active materials constrained in shells

Abstract

Provided are novel electrode material composite structures containing high capacity active materials formed into porous base structures. The structures also include shells that encapsulate these porous base structures. During lithiation of the active material, the shell mechanically constrains the porous base structure. The shell allows lithium ions to pass through but prevents electrolyte solvents from interacting with the encapsulated active material. In certain embodiments, the shell contains carbon, while the porous base structure contains silicon. Although silicon tends to swell during lithiation, the porosity of the base structure and/or void spaces inside the shell helps to accommodate this additional volume within the shell without breaking it or substantially increasing the overall size of the composite structure. This allows integration of the composite structures into various types of battery electrodes and cycling high capacity active materials without damaging the electrodes' internal structures and deteriorating cycling characteristics of batteries.

1 .- 10 . (canceled) 
     
     
         11 . A carbon-encapsulated material, comprising:
 a carbon shell defining an internal volume;   a high-capacity active material disposed within the internal volume;   
       wherein the high-capacity active material occupies less than all of the internal volume, thus defining void space within the carbon shell. 
     
     
         12 . The carbon-encapsulated material of  claim 11 , wherein the high-capacity active material is selected from the group consisting of crystalline silicon, amorphous silicon, silicon oxides, and tin-containing materials. 
     
     
         13 . The carbon-encapsulated material of  claim 11 , wherein the high-capacity active material is selected from the group consisting of crystalline silicon, amorphous silicon, silicon oxides, silicon oxy-nitrides, tin-containing materials, sulfur-containing materials, and germanium-containing materials. 
     
     
         14 . The carbon-encapsulated material of  claim 11 , wherein the carbon shell has an average principal dimension between 50 nanometers and 30 micrometers. 
     
     
         15 . The carbon-encapsulated material of  claim 11 , wherein the carbon shell has an average thickness of between 5 nanometers and 25 nanometers. 
     
     
         16 . The carbon-encapsulated material of  claim 11 , wherein the carbon shell is a monolithic encapsulating structure. 
     
     
         17 . The carbon-encapsulated material of  claim 11 , wherein the high-capacity active material comprises multiple structures. 
     
     
         18 . The carbon-encapsulated material of  claim 11 , wherein the high-capacity active material is porous. 
     
     
         19 . The carbon-encapsulated material of  claim 11 , wherein the carbon-encapsulated material has a form selected from the group consisting of particles, rods, tubes, and wires with aspect ratios greater than four. 
     
     
         20 . A battery electrode comprising the carbon-encapsulated material of  claim 11 . 
     
     
         21 . A battery comprising:
 an anode;   a cathode; and   an electrolyte disposed between the anode and the cathode,   wherein at least one of the anode or the cathode includes the carbon-encapsulated material of  claim 11 .