Phase-pure lithium aluminium titanium phosphate and method for its production and its use

Abstract

The present invention relates to a method for producing lithium aluminum titanium phosphates of the general formula Li 1+x Ti 2−x Al x (PO 4 ) 3, wherein x is ≦0.4, a method for their production as well as their use as solid-state electrolytes in lithium ion accumulators.

1 . Phase-pure lithium aluminum titanium phosphate of the formula Li 1+x Ti 2−x Al x (PO 4 ) 3,  wherein x is ≦0.4 and the level of magnetic metals and magnetic metal compounds of the elements Fe, Cr and Ni therein is ≦1 ppm. 
     
     
         2 . Lithium aluminum titanium phosphate according to  claim 1 , the particle-size distribution d 90  of which is <6 μm. 
     
     
         3 . Lithium aluminum titanium phosphate according to  claim 1  or  2 , the metal iron and magnetic iron compounds content of which is <0.5 ppm. 
     
     
         4 . Lithium aluminum titanium phosphate according to  claim 3 , wherein the value for x is 0.2 or 0.3. 
     
     
         5 . Method for producing Li 1+x Ti 2−x Al x (PO 4 ) 3 , wherein x is ≦0.4, according to one of the previous claims, comprising the steps of
 a) providing a concentrated phosphoric acid 
 b) adding a mixture of a lithium compound, titanium dioxide and an oxygen-containing aluminum compound, 
 c) heating the mixture in order to obtain a solid intermediate product, 
 d) calcining the solid intermediate product. 
 
     
     
         6 . Method according to  claim 5 , wherein liquid concentrated phosphoric acid or aqueous concentrated phosphoric acid is used as phosphoric acid; and/or wherein concentrated orthophosphoric acid or 85% orthophosphoric acid is used as phosphoric acid. 
     
     
         7 . Method according to  claim 5  or  6 , wherein lithium carbonate is used as lithium compound. 
     
     
         8 . Method according to one of  claims 5  to  7 , wherein Al(OH) 3  is used as oxygen-containing aluminum compound. 
     
     
         9 . Method according to one of  claims 5  to  8 , wherein the step of heating is carried out at a temperature of from 200 to 300° C. 
     
     
         10 . Method according to  claim 9 , wherein the calcining takes place at 850 to 1000° C. 
     
     
         11 . Method according to  claim 10 , wherein the calcining is carried out over a period of from 5 to 24 hours. 
     
     
         12 . Method according to one of the previous  claims 5  to  11 , wherein a stoichiometric excess of lithium compound is used in step b). 
     
     
         13 . Phase-pure lithium aluminum titanium phosphate of the formula Li 1+x Ti 2−x Al x (PO 4 ) 3 , wherein x is ≦0.4, obtainable by the method according to one of the previous  claims 5  to  12 . 
     
     
         14 . Use of phase-pure lithium aluminum titanium phosphate according to  claim 1  to  4  or  13  as solid electrolyte in a secondary lithium ion battery. 
     
     
         15 . Secondary lithium ion battery containing phase-pure lithium aluminum titanium phosphate according to one of  claim 1  to  4  or  13 . 
     
     
         16 . Secondary lithium ion battery according to  claim 15 , further containing, as cathode material, a doped or non-doped lithium transition metal phosphate. 
     
     
         17 . Secondary lithium ion battery according to  claim 16 , wherein the transition metal of the lithium transition metal phosphate is selected from Fe, Co, Ni, Mn, Cu, Cr. 
     
     
         18 . Secondary lithium ion battery according to  claim 17 , wherein the transition metal is Fe. 
     
     
         19 . Secondary lithium ion battery according to  claim 18 , wherein the cathode material contains a further doped or non-doped lithium transition metal oxo compound. 
     
     
         20 . Secondary lithium ion battery according to one of  claims 15  to  19 , wherein the anode material contains a doped or non-doped lithium titanate.