Li4Ti5O12, Li(4-a)ZaTi5O12 OR Li4ZbetaTi(5-beta)O12 particles, process for obtaining same and use as electrochemical generators

Abstract

Synthesis process for new particles of Li 4 Ti 5 O 12 , Li( 4-α) Z α Ti 5 O 12 or Li 4 Z β Ti (5-β) O 12 , preferably having a spinel structure, wherein β is greater than 0 and less than or equal to 0.5 (preferably having a spinel structure), a representing a number greater than zero and less than or equal to 0.33, Z representing a source of at least one metal, preferably chosen from the group made up of Mg, Nb, Al, Zr, Ni, Co. These particles coated with a layer of carbon notably exhibit electrochemical properties that are particularly interesting as components of anodes and/or cathodes in electrochemical generators.

1 . A process for synthesizing Li 4 Ti 5 O 12  particles coated with carbon, wherein said particles comprise from 0.01 to 10% by weight of carbon, the quantity of carbon being expressed with respect to the total weight of the Li 4 Ti 5 O 12  particles, said process comprising the steps of: 
 a) preparing a dispersion of an intimate ternary mixture of TiO x —Li z Y-carbon, wherein 
 x is a number between 1 and 2,  
 z is 1 or 2, and  
 Y is a radical selected from the group consisting of CO 3 , OH, O, TiO 3  and mixtures thereof; and  
   b) heating the dispersion at least partially under inert atmosphere;    wherein the operating conditions are chosen in such a way as to yield a conversion of the initial products into Li 4 Ti 5 O 12  coated with carbon.    
     
     
         2 . A process for synthesizing particles of Li (4-α) Z α Ti 5 O 12  coated with carbon, wherein a is a number greater than zero and less than or equal to 0.33 and Z is a source of at least one metal, wherein said particles contain from 0.01 to 10% by weight of carbon, the quantity of carbon being expressed with respect to the total weight of the Li (4-α) Z α Ti 5 O 12  particles, said process comprising the steps of: 
 a) preparing a dispersion of an intimate ternary mixture of TiO x —Li z Y-carbon, wherein 
 x is a number between 1 and 2,  
 z is 1 or 2, and  
 Y is a radical chosen among CO 3 , OH, O and TiO 3  or a mixture thereof;  
   b) heating the dispersion at a temperature of between 400 and 1000° C.; and    c) adding a source of at least one metal Z to the ternary mixture;    wherein the operating conditions are chosen in such a way as to yield a conversion of the initial products into Li (4-α) Z α Ti 5 O 12  coated with carbon.    
     
     
         3 . A process for synthesizing particles of the formula Li 4 Z β Ti (5-β) O 12 , wherein β is greater than 0 and less than or equal to 0.5, coated with carbon and Z is a source of at least one metal, said particles containing from 0.01 to 10% by weight of carbon, the quantity of carbon being expressed with respect to the total weight of the particles of Li 4 Z β Ti (5-β) O 12  formula; said process comprising the steps of: 
 a) preparing a dispersion of an intimate ternary mixture of TiO x —Li z Y-carbon, wherein 
 x is a number between 1 and 2,  
 z is 1 or 2, and  
 Y is a radical selected from the group consisting of CO 3 , OH, O and TiO 3  and mixtures thereof; and  
   b) heating the dispersion at least partially under inert atmosphere; and    c) adding a source of at least one metal Z to the ternary reaction mixture;    wherein the operating conditions are chosen in such a way as to yield a conversion of the initial products into Li 4 Z β Ti (5-β) O 12  coated with carbon.    
     
     
         4 . The process of  claim 1 , wherein the dispersion of the ternary mixture is heated at a temperature of about 600° C.  
     
     
         5 . The process of  claim 4 , wherein the dispersion is heated in two steps, the first step being carried out until the dispersion reaches a temperature of about 400° C. and the second step being carried out until the dispersion reaches a temperature of about 600° C.  
     
     
         6 . The process of  claim 5 , wherein the first step is carried out by rapid heating to around 400° C.  
     
     
         7 . The process of  claim 5 , wherein the second step is carried out by slow heating.  
     
     
         8 . The process of  claim 5 , wherein at least one step of step a) or step b) is carried out in air.  
     
     
         9 . The process of  claim 5 , wherein at least one step of step a) or step b) is carried out at least in part in inert atmosphere.  
     
     
         10 . The process of  claim 1 , wherein dispersion of the ternary mixture is prepared using water and/or at least one solvent.  
     
     
         11 . The process of  claim 1 , wherein the dispersion is carried out dry, without solvent.  
     
     
         12 . The process of  claim 1 , wherein the Li z Y compound comprises at least one compound selected from the group consisting of Li 2 O, Li 2 CO 3 , and LiOH.  
     
     
         13 . The process of  claim 12 , wherein the Li z Y compound comprises exclusively Li 2 CO 3 .  
     
     
         14 . The process of  claim 1 , wherein the dispersion is carried out by mechanical milling.  
     
     
         15 . The process of  claim 1 , wherein TiO x  is of the anatase or rutile TiO 2  type, or a mixture of both.  
     
     
         16 . The process of  claim 1 , wherein the compound Li z Y comprises Li 2 TiO 3 .  
     
     
         17 . The process of  claim 1 , wherein the carbon is: 
 selected from the group consisting of natural or artificial graphite, carbon black, Shawinigan black, Ketjen black and cokes and is added to the reaction mixture;    produced in the course of said process; or    produced at the surface of the particles by calcination of an organic and/or inorganic material deposited, in the course of said process, on the surface of the Li 4 Ti 5 O 2  and/or on the surface of the particles based on Li 4 Ti 5 O 12  and/or on the surface of at least one reagent used for the preparation of the dispersion of said ternary mixture.    
     
     
         18 . The process of  claim 1 , wherein the carbon is in the form of particles having a specific surface area greater than or equal to 2 m 2 /g.  
     
     
         19 . The process of  claim 1 , wherein the process is carried out in the presence of an atmosphere containing oxygen and wherein a part of the carbon present in the ternary mixture is consumed during said process.  
     
     
         20 . The process of  claim 1 , wherein a coating of carbon is obtained from the presence of a powder of Shawinigan carbon and/or at least one polymer.  
     
     
         21 . The process of  claim 15 , wherein the TiO 2  used as an initial product is coated with at least one inorganic material.  
     
     
         22 . The process of  claim 15 , wherein the TiO 2  used is coated with a hybrid inorganic-organic material.  
     
     
         23 . The process of  claim 1 , wherein the size of particles in the ternary mixture is between 100 nanometers and 10 micrometers.  
     
     
         24 . A particle obtained by the process of  claim 1 .  
     
     
         25 . A particle comprising a nucleus coated with carbon, wherein the nucleus of said particle is based on: 
 Li 4 Ti 5 O 12 ; and/or    Li (4-α) Z α Ti 5 O 12 , wherein a is greater than zero and less than or equal to 0.33 and wherein Z is a source of at least one metal; and/or    at least one compound of the formula Li 4 Z β Ti (5-β) O 12 , wherein β is greater than 0 and/or less than or equal to 0.5 and Z is a source of at least one metal.    
     
     
         26 . The particle of  claim 25 , wherein the nucleus comprises at least 65% of Li 4 Ti 5 O 12 , Li (4-α) Z α Ti 5 O 12 , Li 4 Z β Ti (5-β) O 12 , or a mixture thereof.  
     
     
         27 . The particle of  claim 26 , wherein the nucleus is exclusively made up of Li 4 Ti 5 O 12 , Li (4-α) Z α Ti 5 O 12 , Li 4 Z β) Ti (5-β) O 12 , or a mixture thereof.  
     
     
         28 . The particle of  claim 25 , wherein said particle has a reversible capacity between 155 and 170 mAh/g.  
     
     
         29 . The particle of  claim 25 , wherein said particle comprises a nucleus of Li 4 Ti 5 O 12  particles coated with a carbon layer.  
     
     
         30 . The particle of  claim 25 , wherein said particle has a size between 10 and 950 nanometers.  
     
     
         31 . The particle of  claim 25 , wherein the size of the nucleus of said particle is between 10 and 500 nanometers.  
     
     
         32 . The particle of  claim 25 , wherein the thickness of the carbon coating is between 10 and 450 nanometers.  
     
     
         33 . A cathode of an electrochemical generator comprising at least one particle of  claim 25 .  
     
     
         34 . An anode for an electrochemical generator comprising at least one particle of  claim 25 .  
     
     
         35 . An electrochemical generator of the lithium type comprising an anode of the metallic lithium type and a cathode of  claim 33 , wherein said cathode is of the Li 4 Ti 5 O 12  type and/or of the Li (4-α) Z α Ti 5 O 12  type and/or of the Li 4 Z β Ti (5-β) O 12  type.  
     
     
         36 . An electrochemical generator of the lithium-ion type comprising an anode of  claim 34 , wherein said anode is of the Li 4 T 5 O 12  type and/or the Li (4-α) Z α Ti 5 O 12  type and/or the Li 4 Z β Ti (5-β) O 12 , and a cathode of the LiFePO 4 , LiCoO 2 , LiMn 2 O 4  and/or LiNiO 2  type.  
     
     
         37 . An electrochemical generator of  claim 35 , wherein the anode and/or the cathode are equipped with a current collector of solid aluminum or of expanded metal (Exmet) type.  
     
     
         38 . An electrochemical generator of  claim 35 , wherein said generator does not require any prior forming of the battery.  
     
     
         39 . A hybrid-type supercapacitor comprising an anode of  claim 34 , wherein said anode is of the Li 4 Ti 5 O 12  type and/or the Li (4-α) Z α Ti 5 O 12  type and/or the Li 4 Z β Ti (5-β) O 12  and a cathode of the graphite or carbon type with a specific surface area, and wherein the supercapacitor does not require any preliminary formation.  
     
     
         40 . The supercapacitor of  claim 38 , wherein the anode and/or the cathode are equipped with a current collector of solid aluminum or of expanded metal (Exmet) type.  
     
     
         41 . A generator of  claim 35 , further comprising a dry polymer, gel, liquid, or ceramic electrolyte.  
     
     
         42 . A supercapacitor of  claim 39 , further comprising a dry polymer, gel, liquid, or ceramic electrolyte.  
     
     
         43 . The process of  claim 1 , wherein the concentration of components of the ternary mixture submitted to dispersion is chosen in such a way as to yield a conversion of the initial products into Li 4 Ti 5 O 12 .  
     
     
         44 . The process of  claim 2 , wherein the concentration of components of the ternary mixture submitted to dispersion is chosen in such a way as to yield a conversion of the initial products into Li (4-α) Z α Ti 5 O 12 .  
     
     
         45 . The process of  claim 3 , wherein the concentration of components of the ternary mixture submitted to dispersion is chosen in such a way as to yield a conversion of the initial products into Li 4 Z β Ti (5-β) O 12 .  
     
     
         46 . A nano-particle obtained by the process of  claim 1.