Process for the preparation of porous crystalline lithium-, vanadium and phosphate-comprising materials

Abstract

The present invention relates to a process for the preparation of compounds of general formula (I): Li a−b M 1 b V 2-c M 2 c (PO 4 ) x ; wherein M 1 , M 2 , a, b, c and x have the following meanings: M 1 : Na, K, Rb and/or Cs, M 2 : Ti, Zr, Nb, Cr, Mn, Fe, Co, Ni, Al, Mg and/or Sc, a: 1.5-4.5, b: 0-0.6, c: 0-1.98 and x: number to equalize the charge of Li and V and M 1 and/or M 2 , if present, wherein a−b is >0, to a compound according to general formula (I) as defined above, to spherical agglomerates and/or particles comprising at least one compound of general formula (I) as defined above, to the use of such a compound for the preparation of a cathode of a lithium ion battery or an electrochemical cell, and to a cathode for a lithium ion battery, comprising at least one compound as defined above.

1 . A process for the preparation of compounds of general formula (I)
   Li a−b M 1   b V 2-c M 2   c (PO 4 ) x   (I)   wherein M 1 , M 2 , a, b, c and x have the following meanings:   M 1 : Na, K, Rh and/or Cs,   M 2 : Ti, Zr, Nb, Cr, Mn, Fe, Co, Ni, Al, Mg and/or Sc,   a: 1.5-4.5,   b: 0-0.6,   c: 0-1.98 and   x: number to equalize the charge of Li and V and M 1  and/or M 2 , if present,   wherein a−b is >0,   said process comprising   (A) providing an essentially aqueous mixture comprising as substrates at least one lithium-containing compound, at least one vanadium-containing compound in which vanadium has the oxidation state +5 and/or +4, and at least one M 1 -containing compound, if present, and/or at least one M 2 -containing compound, if present, at least one reducing agent which is oxidized to at least one compound comprising at least one phosphorous atom in oxidation state +5 and optionally at least one compound being able to generate at least one gaseous compound and/or at least one precursor of a gaseous compound,   (B) drying the mixture provided in (A), in order to obtain a solid compound and   (C) calcining the solid compound obtained from (B) at a temperature of 300 to 950° C.,   wherein at least one of the substrates generates at least one gaseous compound and/or at least one precursor of a gaseous compound and the at least one gaseous compound and/or the gaseous compound generated from the at least one precursor of a gaseous compound is liberated in (B) and/or (C).   
     
     
         2 . The process according to  claim 1 , wherein the essentially aqueous solution which is provided in (A) additionally comprises at least one compound comprising at least one phosphorous atom in oxidation state +5. 
     
     
         3 . The process according to  claim 1 , wherein the compound which is able to generate at least one gaseous compound is chosen from the group consisting of NH 3 , NH 4 -SaItS and mixtures thereof. 
     
     
         4 . The process according to  claim 3 , wherein the NH 4 -salts are chosen from the group consisting of NH 4 NO 3 , NH 4 NO 2 , NH 4 Cl, NH 4 OAc, NH 4 -formate and mixtures thereof. 
     
     
         5 . The process according to  claim 1 , wherein the at least one reducing agent which is oxidized to at least one compound comprising at least one phosphorous atom in oxidation state +5 is chosen from the group consisting of H 3 PO 3 , (NH 4 )H 2 PO 3 , (NH 4 ) 2 HPO 3 , (NH 4 ) 3 PO 3 , H 3 PO 2 , (NH 4 )H 2 PO 2 , (NH 4 ) 2 HPO 2 , (NH 4 ) 3 PO 2  and mixtures thereof. 
     
     
         6 . The process according to  claim 2 , wherein the at least one compound comprising at least one phosphorous atom in oxidation state +5 which is added in (A) is chosen from the group consisting of H 3 PO 4 , (NH 4 )H 2 PO 4 , (NH 4 ) 2 HPO 4 , (NH 4 ) 3 PO 4  and mixtures thereof. 
     
     
         7 . A compound according to general formula (I)
   Li a−b M 1   b V 2-c M 2   c (PO 4 ) x   (I)   wherein M 1 , M 2 , a, b, c and x have the following meanings:   M 1 : Na, K, Rb and/or Cs,   M 2 : Ti, Zr, Nb, Cr, Mn, Fe, Co, Ni, Al, Mg and/or Sc,   a: 1.5-4.5,   b: 0-0.6,   c: 0-1.98 and   x: number to equalize the charge of Li and V and M 1  and/or M 2 , if present,   wherein a−b is >0,   obtained by a process according to  claim 1 .   
     
     
         8 . A spherical agglomerate and/or particle comprising at least one compound of general formula (I) as defined in  claim 7  having channels going from the inside of the agglomerate and/or particle to the outer surface. 
     
     
         9 . A method of using a compound according to  claim 7  for the preparation of a cathode of a lithium-ion battery or an electrochemical cell. 
     
     
         10 . A cathode for a lithium-ion battery, comprising at least one compound according to  claim 7 . 
     
     
         11 . A process for the preparation of a mixture comprising at least one compound according to general formula (I)
   Li a−b M 1   b V 2-c M 2   c (PO 4 ) x   (I)   wherein M 1 , M 2 , a, b, c and x have the following meanings:   M 1 : Na, K, Rb and/or Cs,   M 2 : Ti, Zr, Nb, Cr, Mn, Fe, Co, Ni, Al, Mg and/or Sc,   a: 1.5-4.5,   b: 0-0.6,   c: 0-1.98 and   x: number to equalize the charge of Li and V and M 1  and/or M 2 , if present,   wherein a−b is >0,   and at least one electrically conducting material, said process comprising   (D) providing an essentially aqueous mixture comprising at least one electrically conducting material, and as substrates at least one lithium-containing compound, at least one vanadium-containing compound in which vanadium has the oxidation state +5 and/or +4, and at least one M 1 -containing compound, if present, and/or at least one M 2 -containing compound, if present, at least one reducing agent which is oxidized to at least one compound comprising at least one phosphorous atom in oxidation state +5 and optionally at least one compound being able to generate at least one gaseous compound and/or at least one precursor of a gaseous compound,   (E) drying the mixture provided in (D), in order to obtain a solid compound and   (F) calcining the solid compound obtained from (E) at a temperature of 300 to 950° C.,   wherein at least one of the substrates generates at least one gaseous compound and/or at least one precursor of a gaseous compound and the at least one gaseous compound and/or the gaseous compound generated from the at least one precursor of a gaseous compound is liberated in (E) and/or (F).   
     
     
         12 . The process according to  claims 11 , wherein the essentially aqueous solution which is provided in (D) additionally comprises at least one compound comprising at least one phosphorous atom in oxidation state +5. 
     
     
         13 . The process according to  claim 11 , wherein the at least one reducing agent which is oxidized to at least one compound comprising at least one phosphorous atom in oxidation state +5 is chosen from the group consisting of H 3 PO 3 , (NH 4 )H 2 PO 3 , (NH 4 ) 2 HPO 3 , (NH 4 ) 3 PO 3 , H 3 PO 2 , (NH 4 )H 2 PO 2 , (NH 4 ) 2 HPO 2 , (NH 4 ) 3 PO 2  and mixtures thereof. 
     
     
         14 . The process according to  claim 11 , wherein the electrically conducting material is chosen from the group consisting of carbon black, graphite, carbon fibres, carbon nanofibres, carbon nanotubes, electrically conducting polymers and mixtures thereof. 
     
     
         15 . A mixture, comprising at least one compound according to general formula (I)
   Li a−b M 1   b V 2-c M 2   c (PO 4 ) x   (I)   wherein M 1 , M 2 , a, b, c and x have the following meanings:   M 1 : Na, K, Rb and/or Cs,   M 2 : Ti, Zr, Nb, Cr, Mn, Fe, Co, Ni, Al, Mg and/or Sc,   a: 1.5-4.5,   b: 0-0.6,   c: 0-1.98 and   x: number to equalize the charge of Li and V and M 1  and/or M 2 , if present,   wherein a−b is >0,   and at least one electrically conducting material, obtained by a process according to  claim 11 .   
     
     
         16 . A spherical agglomerate and/or particle comprising at least one compound of general formula (I) as defined in  claim 7  and at least one electrically conducting material having channels going from the inside of the agglomerate to the outer surface. 
     
     
         17 . A method of using a mixture according to  claim 15  for the preparation of a cathode of a lithium ion battery or an electrochemical cell. 
     
     
         18 . A cathode for a lithium-ion battery, comprising a mixture according to  claim 15 .