Metal Foam for Electrode of Secondary Lithium Battery, Preparing Method Thereof, and Secondary Lithium Battery Including the Metal Foam

Abstract

Using metal foams for the electrode of secondary lithium battery, preparing method thereof, and secondary lithium battery including the metal foam. A metal foam is used in an electrode of secondary lithium battery where the surface and the inner pore walls are coated with the active materials, a method of manufacturing such metal foam, and secondary lithium battery including the metal foam.

The invention claimed is: 
     
         1 . A secondary lithium battery comprising:
 a porous metal foam electrode wherein at least a portion of a surface and inner pore wall of the electrode are coated with an active material that reacts with lithium.   
     
     
         2 . The battery of  claim 1  wherein the active material can be a cathode or an anode active material. 
     
     
         3 . The battery of  claim 2  wherein the cathode active material is selected from a group consisting of the following LCO(LiCoO 2 ), LMO(LiMn 2 O 4 ), LMO(LiMn 2 O 4 ), LFP(LiFePO 4 ), and LiNi 1 /3Co 1 /3Mn 1 /3O 2 . 
     
     
         4 . The battery of  claim 2  wherein the anode active material can be graphite-based material, metal-based material, or oxide-based material and it is selected from a group consisting of the following: artificial graphite, natural graphite, soft carbon, hard carbon, Si—Li based alloys, In—Li based alloys, Sb—Li based alloys, Ge—Li based alloys, Bi—Li based alloys, Ga—Li based alloys, and oxide based materials including SnO 2 , Co 3 O 4 ,CuO, NiO, and Fe 3 O 4 . 
     
     
         5 . The battery of  claim 1  wherein the metal foam electrode is made of a metal that is selected from a group consisting of the following metal or one of its alloys: aluminum, nickel, copper, gold, magnesium, silver, tin, and stainless steel and their alloys. 
     
     
         6 . The battery of  claim 1  wherein a manufacturing process to form the porous metal foam electrode comprises at least one of the following: powder sintering, space holder method, ice-template method, dealloying, electroplating, and electroless plating. 
     
     
         7 . The batter of  claim 1  wherein the active material is tin oxide and a metal foam of the electrode is copper foam. 
     
     
         8 . A method of making a metal foam using an ice-templating process comprising:
 immersing a copper rod into liquid nitrogen and placing onto the rod a metal powder slurry containing water or other freezing medium, binder, and metal particles;   lowering a temperature to freeze the slurry and form ice dendrites, wherein the metal powders interposed between the ice dendrites become frozen;   forming a green-body porous structure by drying the ice dendrites in the slurry below the freezing point, leaving channel-like pores in their places;   forming metallic foam is by sintering the porous green-body structure in a furnace; and   machining the metallic foam into thin layers, which can be applied as an electrode in a secondary lithium lattery.   
     
     
         9 . A secondary lithium battery including a metal foam as an electrode wherein the metal foam is fabricated by the method of  claim 8 . 
     
     
         10 . A method of fabricating a metal-foam current collector electrode for a secondary lithium battery, comprising a process of coating an active nonmetallic material onto the metal foam current collector electrode comprising a porous copper foam, wherein at least a portion of a surface and inner pore wall are coated with the active nonmetallic material, and after the process of coating an active nonmetallic material onto the metal foam current collector electrode, the current collector electrode remains a metal foam comprising pores. 
     
     
         11 . The method of  claim 10  wherein the metal foam is coated with an active nonmetallic material using at least one of the following methods: ion-plating, sol-gel process, co-precipitation, electroless plating, or impregnation. 
     
     
         12 . The method of  claim 11  wherein a sol-gel process is used to coat at least a portion the surface and inner pore wall of the metal foam with the active nonmetallic material. 
     
     
         13 . The method of  claim 12  wherein the process of coating an active nonmetallic material onto the metal foam current collector electrode for use as an electrode plus current collector of a secondary lithium battery comprises using sol-gel process comprising:
 preparing a sol-solution that contains precursor compound; 
 permeating the sol-solution into the inside and onto the metal foam; 
 drying the metal foam; and 
 heat-treating the metal foam. 
 
     
     
         14 . The method of  claim 12  wherein a precursor compound, which is required for the synthesis of an active nonmetallic material, is selected from a group consisting of the following: SnCl4, Sn(CH3COO)2, Sn(NO3)2, SnCO3, Sn(CH3)4, and (CH3)2SnCl2, Sn(C4H9)2(CHCOO)2, and Sn(XR)2 [X═O, S, or N; R=Me, Et, i-PR, or T-Bu]. 
     
     
         15 . The method of  claim 13  wherein a first coating layer is formed onto the metal foam, and when the first coating layer is a metal oxide, then a second coating layer is obtained through an additional reduction process of the first coating under a hydrogen atmosphere, the second coating layer is a metallic coating comprising a metal element of the metal oxide of the first layer, and the coating on the active nonmetallic material is the second coating layer. 
     
     
         16 . The method of  claim 10  wherein an initial coating layer is a metal oxide and a metallic coating layer is subsequently obtained a transformation through an additional reduction process of the initial coating under hydrogen atmosphere. 
     
     
         17 . The method of  claim 15  comprising:
 applying a pure Sn coating onto the surface and inner pore wall of the metal foam by using an electroless technique. 
 
     
     
         18 . The method of  claim 16  wherein the metallic coating layer comprise a metal element of the metal oxide of the initial coating layer, and the coating on the active nonmetallic material is the metallic coating layer. 
     
     
         19 . The method of  claim 10  wherein an initial coating layer is a metal oxide, and a metallic coating layer is obtained through an electroless coating process by transforming the metal oxide of the initial coating layer into a metal of a metal element of the metal oxide. 
     
     
         20 . The method of  claim 17  comprising:
 applying anodizing to the Sn coating to form SnO2 needles on the surface of the pure Sn coating.