Preparation Of Epsilon-Phase Silver Vanadium Oxide From Gamma-Phase SVO Starting Material

Abstract

The current invention relates to the preparation of an improved cathode active material for non-aqueous lithium electrochemical cell. In particular, the cathode active material comprises ε-phase silver vanadium oxide prepared by using a γ-phase silver vanadium oxide starting material. The reaction of γ-phase SVO with a silver salt produces the novel ε-phase SVO possessing a lower surface area than ε-phase SVO produces from vanadium oxide (V 2 O 5 ) and a similar silver salt as starting materials. Consequently, the low surface area ε-phase SVO material provides an advantage in greater long-term stability in pulse dischargeable cells.

1 . A cathode for an electrochemical cell, the cathode comprising an ε-phase silver vanadium oxide characterized as prepared from a mixture of γ-phase silver vanadium oxide having the formula Ag 1.2 V 3 O 8.1  and a metal salt to form a reaction mixture heated to at least one reaction temperature in an oxidizing atmosphere to produce the ε-phase silver vanadium oxide having the formula Ag 2 V 4 O 11 , wherein the metal salt is selected from one of: 
 Ag 2 O and the ε-phase silver vanadium oxide has a BET surface area of about 0.54 m 2 /gram, and    Ag 2 CO 3  and the ε-phase silver vanadium oxide has a BET surface area of about 0.44 m 2 /gram.    
   
   
       2 . The cathode of  claim 1  wherein the reaction mixture is heated to the at least one reaction temperature in a range from about 300° C. to about 550° C.  
   
   
       3 . The cathode of  claim 1  wherein the reaction mixture is heated to the at least one reaction temperature for about 5 hours to about 30 hours.  
   
   
       4 . The cathode of  claim 1  further comprising a binder and a conductive material.  
   
   
       5 . A nonaqueous electrochemical cell, comprising: 
 a) an anode;    b) a cathode containing an electrode active material characterized as having been prepared from a mixture of γ-phase silver vanadium oxide having the formula Ag 1.2 V 3 O 8.1  and a metal salt forming a reaction mixture heated to at least one reaction temperature in an oxidizing atmosphere to produce the electrode active material selected from one of: 
 i) Ag 2 V 4 O 11  having a BET surface area of about 0.54 m 2 /gram with the metal salt having been Ag 2 O; and  
 ii) Ag 2 V 4 O 11  having a BET surface area of about 0.44 m 2 /gram with the metal salt having been Ag 2 CO 3 ; and  
   c) a non-aqueous electrolyte activating the anode and the cathode; and    d) a separator material electrically insulating the anode from the cathode, and of a porosity to allow for electrolyte flow.    
   
   
       6 . The electrochemical cell of  claim 5  wherein the anode is comprised of lithium.  
   
   
       7 . The electrochemical cell of  claim 5  wherein the reaction mixture is heated to the at least one reaction temperature in a range from about 300° C. to about 550° C.  
   
   
       8 . The electrochemical cell of  claim 5  wherein the reaction mixture is heated to the at least one reaction temperature for about 5 hours to about 30 hours.  
   
   
       9 . A cathode for an electrochemical cell, the cathode comprising an electrode active material characterized as prepared from γ-phase silver vanadium oxide having the formula Ag 1.2 V 3 O 8.1  mixed with a metal salt compound to form a reaction mixture heated to at least one reaction temperature in an oxidizing atmosphere to produce the electrode active material selected from the group consisting of Mn 0.2 Ag 0.8 V 2 O 5.8 , and Mg 0.2 Ag 0.8 V 2 O 5.6 .  
   
   
       10 . The cathode of  claim 9  wherein the metal salt is selected from the group consisting of manganese carbonate, manganese oxide, magnesium carbonate, magnesium oxide, and combinations and mixtures thereof.