Particles Containing a Non-Conducting or Semi-Conducting Nucleus Covered with a Hybrid Conducting layer, Their Processes of Preparation and uses in Electrochemical Devices

Abstract

Mixture of particles comprising a non-conducting or semi-conducting nucleus covered with a hybrid conductor coating and hybrid conductor chains located between the particles of the mixture to constitute a conductivity network, that is prepared by mechanical crushing. Due to a very good conductivity of the network, a low resistivity, a very good capacity under elevated current and/or a good density of energy, these mixtures of particles are advantageously incorporated in anodes and cathodes of electrochemical generators, resulting in highly performing electrochemical systems.

1 - 76 . (canceled) 
     
     
         77 . Mixture of particles comprising a non-conducting or semi-conducting nucleus, the nuclei of said particles being at least partially covered with a hybrid conductor coating and said particles being at least partially connected through hybrid conducting chains which provide a network of electrical conductivity, wherein:
 the nucleus of said particles is at least 65% of one lithium oxide selected from the group consisting of oxides of the formula:
 Li 4 Ti 5 O 12 ; 
 Li (4-α) Z α Ti 5 O 12 , in which 0<α≤0.33, Z represents a source of at least one metal; and 
 Li 4 Z β Ti (5-β) O 12  in which 0≤β≤0.5, Z represents at least one metal; 
   each of the hybrid conductor coating and the hybrid conducting chains is a hybrid carbon mixture which comprises at least two different conducting forms of carbon, which are hereunder designated Carbon 1 and Carbon 2, wherein:
 Carbon 1 consists of particles with low crystallinity having a d002 greater than 3.36 Å if measured by X-ray diffraction or by Raman spectroscopy, said Carbon 1 possesses a specific surface area which, as measured by the BET method, is equal to or greater than 50 m 2 /g, and particles of Carbon 1 have an average size varying from 10 to 999 nm, and 
 Carbon 2 consists of at least one of graphite particles and high crystallinity carbon particles with high crystallinity having a d002 smaller than 3.36 Å if measured by X-ray diffraction, particles of Carbon 2 have a specific surface area which, as measured by the BET method, is equal to or smaller than 50 m 2 /g, and the particles of Carbon 2 have a size varying from 2 to 10 μm, 
   wherein the hybrid conductor coating comprises:
 a first, inner coating of Carbon 1 which covers between 50 and 90% of the surface of the nucleus, and 
 a second, outer coating of Carbon 2. 
   
     
     
         78 . Mixture of particles according to  claim 77 , in which the second, outer coating of Carbon 2 comprises particles are connected together to constitute an electrical conductivity network. 
     
     
         79 . Mixture according to  claim 77 , in which the particles have a D 50  of about 7 micrometers. 
     
     
         80 . Mixture according to  claim 77 , in which Z represents a particle of a metal selected from the group consisting of Mg, Nb, Al, Zr, Ni and Co. 
     
     
         81 . Mixture according to  claim 77 , containing from 1 to 6% by weight of carbon in said mixture. 
     
     
         82 . Mixture according to  claim 81 , containing about 2% by weight of carbon in said mixture. 
     
     
         83 . Mixture according to  claim 77 , in which Carbon 2 is at least one graphite selected from the group consisting of synthetic graphite, natural graphite, exfoliated graphite and mixtures of two or more of these graphite. 
     
     
         84 . Mixture according to  claim 77 , in which the weight percentage of Carbon 1 represents from 1 to 10% of the total weight of the coating composed of Carbon 1 and Carbon 2. 
     
     
         85 . Mixture according to  claim 77 , in which the quantity of Carbon 1 is substantially identical to the quantity of Carbon 2. 
     
     
         86 . Mixture according to  claim 77 , in which the average diameter of the nucleus of said particles varies from 50 nanometers to 30 micrometers. 
     
     
         87 . Mixture according to  claim 86 , wherein the average diameter of said nucleus is of the order of about 2 micrometers. 
     
     
         88 . Mixture according to  claim 77 , in which the average size of said particles, measured according to the electronic scanning microscope method, is between 4 and 30 micrometers. 
     
     
         89 . Mixture according to  claim 77 , having at least one of the following properties: a very good local conductivity, a very good network conductivity, a low resistivity, a very good capacity under elevated current and a good density of energy. 
     
     
         90 . Mixture according to  claim 87 , having a local conductivity, measured according to the four point method, that is higher than 10 −6  (Ohm-m). 
     
     
         91 . Mixture of particles according to  claim 89 , having a network conductivity, measured according to the four point method, that is between 2.6×10 −3  and 6.2×10 −3 . 
     
     
         92 . Process for preparing a mixture of particles such as defined in  claim 77 , comprising at least one of the following steps:
 a) preparation of a mixture of at least one non-conducting or semi-conducting material with a conducting material, and the addition of a second conducting material to the mixture obtained;   b) preparation of a mixture of at least one non-conducting or semi-conducting material with at least two conducting materials; and   c) preparation of a mixture of conducting materials and mixing thereof with at least one non-conducting or semi-conducting material, wherein:   the non conducting material is the lithium oxide; and   the mixture is prepared by High Energy Ball Milling.   
     
     
         93 . Process for preparing a mixture of particles according to  claim 92 , carried out at a temperature lower than about 300° C. 
     
     
         94 . Cathode for electrochemical generator comprising a mixture of particles as defined in  claim 77 . 
     
     
         95 . Anode for electrochemical generator comprising particles as defined in  claim 77 . 
     
     
         96 . Electrochemical generator of the lithium type including at least one metallic lithium anode and at least one cathode as defined in  claim 94 . 
     
     
         97 . Electrochemical generator according to  claim 96 , preferably of the rechargeable and/or recyclable type. 
     
     
         98 . Electrochemical generator of the lithium type including at least one metallic lithium anode as defined in  claim 94 , at least one cathode and comprising at least one electrolyte. 
     
     
         99 . Electrochemical generator according to  claim 96 , in which at least one anode and/or at least one cathode are provided with an aluminum current collector that is full or of the Exmet type (expanded metal). 
     
     
         100 . Electrochemical generator according to  claim 96  requiring no previous preparation of the battery. 
     
     
         101 . Generator according to  claim 96 , in which the electrolyte is a dry polymer, a gel, a liquid or a ceramic. 
     
     
         102 . Hybrid type supercapacitor comprising at least one electrolyte, at least one anode, as defined in  claim 95 , and at least one cathode of the graphite or large surface area carbon type, requiring no previous preparation of the supercapacitor. 
     
     
         103 . Supercapacitor according to  claim 102 , in which at least one anode and/or at least one cathode are provided with an aluminum current collector that is full or of the Exmet type (expanded metal). 
     
     
         104 . Supercapacitor according to  claim 103 , in which the electrolyte is a dry polymer, a gel, a liquid or a ceramic. 
     
     
         105 . Electrochemical system according to  claim 96 , wherein the electrode is prepared without any addition of additional carbon. 
     
     
         106 . Mixture according to  claim 77 , in which at least some of the particles of Carbon 2 are connected together to constitute an electrical conductivity network. 
     
     
         107 . Mixture according to  claim 77 , in which about 80% of Carbon 1 is covering the surface of said nuclei; and about 20% of the particles of Carbon 2 are connected together to constitute an electrical conductivity network. 
     
     
         108 . Mixture according to  claim 77 , in which the nucleus of said particles consists for at least 70% of at least one metal oxide. 
     
     
         109 . Mixture according to  claim 87 , having a local conductivity, measured according to the four point method, that is higher than or equal to 10 −5  (Ohm-m). 
     
     
         110 . Mixture of particles according to  claim 89 , having a network conductivity, measured according to the four point method, that is lower than about 6.0×10 −03  (Ohm-m). 
     
     
         111 . Process for preparing a mixture of particles according to  claim 92 , carried out at a temperature between 20 and 40° C. 
     
     
         112 . Process for preparing a mixture of particles according to  claim 92 , carried out at room temperature. 
     
     
         113 . Cathode for electrochemical generator comprising a mixture of particles capable of being obtained by a process according to  claim 92 . 
     
     
         114 . Anode for electrochemical generator comprising particles capable of being obtained by a process according to  claim 92 . 
     
     
         115 . Anode for electrochemical generator comprising particles comprising a non-conducting or semi-conducting nucleus, the nuclei of said particles being at least partially covered with a hybrid conductor coating and said particles being at least partially connected through hybrid conducting chains which provide a network of electrical conductivity and particles capable of being obtained by a process according to  claim 92 . 
     
     
         116 . Electrochemical generator according to  claim 96 , in which the anode is of the Li 4 Ti 5 O 12  and/or Li (4-α) Z α Ti 5 O 12  and/or Li 4 Z β Ti (5-β) O 12  type. 
     
     
         117 . Electrochemical generator according to  claim 98 , in which the anode is of the Li 4 Ti 5 O 12  and/or Li (4-α) Z α Ti 5 O 12  and/or Li 4 Z β Ti (5-β) O 12  type; and the cathode is of the LiFePO 4 , LiCoO 2 , LiMn 2 O 4  and/or LiNiO 2  type. 
     
     
         118 . Hybrid type supercapacitor comprising at least one electrolyte, at least one anode, of the Li 4 Ti 5 O 12  and/or Li (4-α) Z α Ti 5 O 12  and/or Li 4 Z β Ti (5-β) O 12  type and at least one cathode of the graphite or large surface area carbon type, requiring no previous preparation of the supercapacitor.