Crumpled graphene-encapsulated nanostructures and lithium ion battery anodes made therefrom

Abstract

Capsules comprising crumpled graphene sheets that form a crumpled graphene shell encapsulating an internal cargo comprising nanostructures of a second component are provided. Also provided are anode materials for lithium ion batteries comprising the capsules, wherein the nanostructures are composed of an electrochemically active material, such as silicon.

1 - 12 . (canceled) 
     
     
         13 . An electrode material comprising capsules, each capsule comprising:
 a shell comprising one or more crumpled sheets of graphene, graphene oxide, reduced graphene oxide, or a combination thereof; and   an electrochemically active material encapsulated within the shell,   wherein the electrochemically active material comprises at least 50 wt % of the capsule.   
     
     
         14 . The electrode material of  claim 13 , wherein the sheets comprises graphene. 
     
     
         15 . The electrode material of  claim 13 , wherein the electrochemically active material comprises a monometallic material, a bimetallic material, a multimetallic material, an oxidic material, a sulfide material, or any combinations thereof. 
     
     
         16 . The electrode material of  claim 13 , wherein the electrochemically active material is selected from the group consisting of Si, Ag, Pt, CsCl, Sn, Ge, Sb, TiO 2 , ZnO, SnO 2 , Co 3 O 4 , Fe 2 O 3 , MnO 2 , Mn 3 O 4 , MnO, Fe 3 O 4 , NiO, MoO 2 , MoO 3 , CuO, Cu 2 O, CeO 2 , RuO 2 , or any combinations thereof. 
     
     
         17 . The electrode material of  claim 13 , wherein the electrochemically active material comprises at least 60 wt % of the capsule. 
     
     
         18 . The electrode material of  claim 13 , wherein the capsules are spherical and have a fractal-dimension of between 0.1 nm and 1000 nm. 
     
     
         19 . The electrode material of  claim 13 , wherein the shells are configured to permit free expansion of the electrochemically active material without rupturing, during charging of the electrochemically active material. 
     
     
         20 . The electrode material of  claim 13 , wherein the electrochemically active material comprises particles having an average particle size ranging from about 50 nm to 100 nm. 
     
     
         21 . The electrode material of  claim 13 , wherein the capsules have fractal dimensional values of between 2 and 3. 
     
     
         22 . The electrode material of  claim 13 , wherein, the capsules are configured to isolate the electrochemically active material from an electrolyte solvent. 
     
     
         23 . A method of making capsules, the method comprising:
 forming a dispersion of sheets of graphene, graphene oxide, reduced graphene oxide, or a combination thereof, and an electrochemically active material;   atomizing the dispersion to form aerosol droplets;   transferring the aerosol droplets by way of a carrier gas from the atomizer to a preheated furnace; and   heating the aerosol droplets as the droplets pass through the preheated furnace, such that evaporation-induced capillary forces wrap the sheets around the electrochemically active material and encapsulate the electrochemically active material to form capsules.   
     
     
         24 . The method of  claim 23 , wherein the transferring the aerosol droplets comprises localizing the sheets at the surface of the aerosol droplets. 
     
     
         25 . The method of  claim 23 , wherein the electrochemically active material comprises nanoparticles encapsulated in the capsules. 
     
     
         26 . The method of  claim 25 , wherein the heating further comprises:
 concentrating the sheets in the aerosol droplets; and   crumpling the concentrated sheets to form π-π stacked ridges.   
     
     
         27 . The method of  claim 23 , wherein heating the aerosol droplets comprises heating the aerosol droplets at a temperature of at least about 500° C. 
     
     
         28 . The method of  claim 23 , wherein the method further comprises heating the capsules in an inert atmosphere to thermally reduce the sheets. 
     
     
         29 . The method of  claim 23 , wherein the electrochemically active material is selected from the group consisting of a monometallic, a bimetallic, a multimetallic, an oxidic, a sulfide material, and combinations thereof. 
     
     
         30 . The method of  claim 23 , wherein the electrochemically active material comprises Si, Au, Pt, CsCl, Sn, Ge, Sb, TiO 2 , ZnO, SnO 2 , Co 3 O 4 , Fe 2 O 3 , MnO 2 , Mn 3 O 4 , MnO, Fe 3 O 4 , NiO, MoO 2 , MoO 3 , CuO, Cu 2 O, CeO 2 , RuO 2 , NiO, or combinations thereof. 
     
     
         31 . The method of  claim 23 , wherein the electrochemically active material is a nanostructure, the nanostructure comprising at least one of a nanoparticle, an nanocomposite, a quantum dot, a nanofilm, a nanoshell, a nanofiber, a nanoring, a nanorod, a nanowire, or a nanotube. 
     
     
         32 . The method of  claim 23 , wherein the capsules have a fractal-dimension of between 0.1 nm and 1000 nm.