Synthesis of Metal Compounds Under Carbothermal Conditions

Abstract

Active materials of the invention contain at least one alkali metal and at least one other metal capable of being oxidized to a higher oxidation state. Preferred other metals are accordingly selected from the group consisting of transition metals (defined as Groups 4-11 of the periodic table), as well as certain other non-transition metals such as tin, bismuth, and lead. The active materials may be synthesized in single step reactions or in multi-step reactions. In at least one of the steps of the synthesis reaction, reducing carbon is used as a starting material. In one aspect, the reducing carbon is provided by elemental carbon, preferably in particulate form such as graphites, amorphous carbon, carbon blacks and the like. In another aspect, reducing carbon may also be provided by an organic precursor material, or by a mixture of elemental carbon and organic precursor material.

1 . A composition comprising an active material of formula  
         A a M b O c   
       wherein A comprises an alkali metal, M comprises a transition metal or other metal capable of undergoing oxidation to a higher oxidation state, and a, b, and care non-zero and chosen so as to maintain electroneutrality of the compound, made by a process comprising the steps of: 
 combining starting materials comprising at least one metal compound and at least one source of reducing carbon to form a mixture;  
 heating the mixture at a temperature and for a time sufficient to form a reaction product, wherein at least one metal of the starting material is reduced in oxidation state during heating to form a reduced metal compound; and  
 reacting an alkali metal compound with the reduced metal compound.  
 
     
     
         2 . A composition according to  claim 1 , wherein the reducing carbon comprises elemental carbon.  
     
     
         3 . A composition according to  claim 1 , wherein the reducing carbon comprises an organic material.  
     
     
         4 . A composition according to  claim 1 , wherein the reducing carbon comprises a carbohydrate.  
     
     
         5 . A composition according to  claim 1 , wherein the reducing carbon comprises sucrose.  
     
     
         6 . A composition according to  claim 1 , wherein M is selected from the group consisting of vanadium, chromium, manganese, iron, cobalt, nickel, molybdenum, titanium and mixtures thereof.  
     
     
         7 . A composition according to  claim 1 , wherein the alkali metal compound comprises a lithium compound.  
     
     
         8 . A method of preparing a finely dispersed mixture of electrochemically active material and a conductive carbon, comprising the steps of: 
 preparing a mixture comprising at least one alkali metal compound, at least one metal compound, and a carbon-containing composition selected from the group consisting of elemental carbon and an organic material; and    heating the mixture for a time and at a temperature sufficient to form a reaction product.    
     
     
         9 . A method according to  claim 8 , wherein at least one metal is reduced in oxidation state during the heating step.  
     
     
         10 . A method according to  claim 8 , wherein the reaction proceeds without reduction.  
     
     
         11 . A method according to  claim 8 , wherein the heating step takes places in a reducing atmosphere.  
     
     
         12 . A method according to  claim 11 , wherein the reducing atmosphere comprises hydrogen.  
     
     
         13 . A method according to  claim 8 , wherein the carbon-containing composition comprises elemental carbon in powdered form.  
     
     
         14 . A method according to  claim 8 , wherein the carbon-containing composition is selected from the group consisting of Shawinigan black, graphite, carbon black, and amorphous carbon.  
     
     
         15 . A method according to  claim 8 , wherein the finely dispersed mixture comprises crystals of active material nucleated onto grains of carbon.