Potatolike shaped graphite particles with low impurity rate at the surface, process for preparing same

Abstract

Modified graphite particles obtained from graphite or based on graphite, the said particles having impurities in their internal structure and having on the surface a low, even nil, rate of an impurity or several impurities. In addition, these particles have at least one of the following characteristics: a tab density between 0.3 and 1.5 g/cc; a potatolike shape; and a granulometric dispersion such that the D90/D10 ratio varies between 2 and 5 and the particles have a size between 1 and 50 μm. These particles can be used for fuel cells, electrochemical generators, or as moisture absorbers and/or oxygen absorbers and they have important electrochemical properties. The electrochemical cells and batteries thus obtained are stable and safe.

1 - 34 . (canceled)  
     
     
         35 . Modified graphite-based particles comprising prismatic particles of graphite covered with a metallic deposit or with a metallic and carbonic deposit, wherein the structural parameters of said modified graphite-based particles correspond to the equations fe 1 =[Y+l]/[(Y+1)+(B/2T)(Y−1)] and fe 2 =[Y+l]/[(Y+1)+(B/T) (Y−1)], wherein Y represents a real number greater than or equal to 1, B represents the length of the modified graphite-based particle, and T represents the thickness of the modified graphite-based particle, said modified graphite-based particles having a potatolike shape and at least one characteristic selected from the group consisting of: 
 a tap density between 0.3 and 1.5 g/cc;    a granulometric dispersion such that the D90/D10 ratio varies between 2 and 5;    and the modified graphite-based particles have a size between 1 and 50 μm.    
     
     
         36 . The modified graphite-based particles of  claim 35 , wherein the average thickness of the metallic or the metallic and carbonic deposit covering the prismatic particles of graphite is between 50 nm and 2 μm.  
     
     
         37 . Graphite-based particles comprising a coated graphite core, wherein said core is at least 90% by weight of the total weight of the graphite-based particle and wherein the remainder of the graphite-based particle comprises at least one metal selected from the group consisting of Ag, Si, Al, and Cu and a carbon and/or a carbonated polymer.  
     
     
         38 . A process for preparing modified graphite-based particles of  claim 35 , comprising coating prismatic-shaped particles of graphite while keeping a basal function (fb) and an edge function (fe) constant while wrapping the graphite surface with a metallic or carbonic deposit in such a way as to obtain a sphericity of 80% or more.  
     
     
         39 . A fuel cell comprising modified graphite-based particles of  claim 35 .  
     
     
         40 . An electrochemical generator comprising modified graphite-based particles of  claim 35 .  
     
     
         41 . A moisture absorber comprising modified graphite-based particles of  claim 35 .  
     
     
         42 . An oxygen sensor comprising modified graphite-based particles of  claim 35 .  
     
     
         43 . A negative electrode comprising a bonding agent and modified graphite-based particles of  claim 35 .  
     
     
         44 . The modified graphite-based particles of  claim 35 , wherein the tap density is between 0.5 and 1.4 g/cc.  
     
     
         45 . The modified graphite-based particles of  claim 44 , wherein the tap density is between 1 and 1.3 g/cc.  
     
     
         46 . The modified graphite-based particles of  claim 35 , wherein the modified graphite-based particles have a granulometric dispersion such that the D90/D10 ratio varies between 2.2 and 4.2 and the particles have a size between 2 and 30 μm.  
     
     
         47 . The modified graphite-based particles of  claim 46 , wherein the modified graphite-based particles have a sphericity of 80% or more.  
     
     
         48 . The modified graphite-based particles of  claim 44 , wherein the modified graphite-based particles have a granulometric dispersion such that the D90/D10 ratio varies between 2.2 and 4.2 and the particles have a size between 2 and 30 μm.  
     
     
         49 . The modified graphite-based particles of  claim 45 , wherein the modified graphite-based particles have a granulometric dispersion such that the D90/D10 ratio varies between 2.2 and 4.2 and the particles have a size between 2 and 30 μm.  
     
     
         50 . The graphite-based particles of  claim 37 , wherein the carbon or carbonated polymer is in prismatic or fiber form.  
     
     
         51 . A process for preparing modified graphite-based particles of  claim 37 , comprising coating prismatic-shaped particles of graphite while keeping a basal function (fb) and an edge function (fe) constant while wrapping the graphite surface with a metallic or carbonic deposit in such a way as to obtain a sphericity of 80% or more.  
     
     
         52 . A fuel cell comprising modified graphite-based particles of  claim 37 .  
     
     
         53 . An electrochemical generator comprising modified graphite-based particles of  claim 37 .  
     
     
         54 . A moisture absorber comprising modified graphite-based particles of  claim 37 .  
     
     
         55 . An oxygen sensor comprising modified graphite-based particles of  claim 37 .  
     
     
         56 . A negative electrode comprising a bonding agent and modified graphite-based particles of  claim 37.