Isolation of lithium

Abstract

Lithium is isolated from lithium amalgam by electrolysis over a solid lithium ion conductor having the composition Li 4−x Si 1−x P x O 4 , where x is at least 0.3 and not more than 0.7.

We claim:  
     
         1 . A process for isolating lithium from lithium amalgam by electrolysis over a solid lithium ion conductor, wherein a lithium ion conductor used has the composition Li 4−x Si 1−x P x O 4  where x is at least 0.3 and not more than 0.7.  
     
     
         2 . A process as claimed in  claim 1 , wherein the lithium ion conductor used has the composition Li 4−x Si 1−x P x O 4 , where x is at least 0.4 and not more than 0.6.  
     
     
         3 . A process as claimed in  claim 2 , wherein the lithium ion conductor used has the composition Li 4−x Si 1−x P x O 4 , where x is about 0.5.  
     
     
         4 . A process as claimed in one of claims  1 ,  2  or  3 , wherein the lithium ion conductor used is prepared by shaping and calcining Li 4−x Si 1−x P x O 4 , where x is at least 0.3 and not more than 0.7, and/or compounds which are converted into this during calcination, where the Li 4−x Si 1−x P x O 4  and/or the compounds is/are used in the form of powder having a mean particle size of not more than 5 microns.  
     
     
         5 . A process as claimed in  claim 4 , wherein the Li 4−x Si 1−x P x O 4  and/or the compounds is/are used in the form of powder having a mean particle size of not more than 3 microns.