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 produced 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.

What is claimed is:  
     
         1 . A cathode for an electrochemical cell, the cathode comprising an ε-phase silver vanadium oxide characterized as prepared by heating a silver vanadium compound mixed with a metal salt to form a reaction mixture heated to at least one reaction temperature in an oxidizing atmosphere to produce the e-phase silver vanadium oxide having the formula Ag 2 V 4 O 11 .  
     
     
         2 . The cathode of  claim 1  wherein the silver vanadium compound is γ-phase silver vanadium oxide having the formula Ag 1.2 V 3 O 8.1 .  
     
     
         3 . The cathode of  claim 1  wherein the metal salt is selected from the group consisting of silver lactate, silver triflate, silver pentafluoropropionate, silver laurate, silver myristate, silver palmitate, silver stearate, silver vanadate, silver oxide, silver carbonate, copper oxide, copper carbonate, manganese carbonate, manganese oxide, magnesium carbonate, magnesium oxide, and combinations and mixtures thereof.  
     
     
         4 . The cathode of  claim 1  wherein the metal salt is Ag 2 O and the ε-phase silver vanadium oxide has a BET surface area of about 0.54 m 2 /g.  
     
     
         5 . The cathode of  claim 1  wherein the metal salt is Ag 2 CO 3  and the ε-phase silver vanadium oxide has a BET surface area of about 0.44 m 2 /g.  
     
     
         6 . 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.  
     
     
         7 . 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.  
     
     
         8 . The cathode of  claim 1  further comprising a binder and a conductive material.  
     
     
         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 Ag 2 V 4 O 11 , Cu 0.2 Ag 0.8 V 2 O 5.6 , 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 silver lactate, silver triflate, silver pentafluoropropionate, silver laurate, silver myristate, silver palmitate, silver stearate, silver vanadate, silver oxide, silver carbonate, copper oxide, copper carbonate, manganese carbonate, manganese oxide, magnesium carbonate, magnesium oxide, and combinations and mixtures thereof.  
     
     
         11 . The cathode of  claim 9  wherein the metal salt is Ag 2 O such that the product electrode active material having the formula Ag 2 V 4 O 11  has a BET surface area of about 0.54 m 2 /g.  
     
     
         12 . The cathode of  claim 9  wherein the metal salt is Ag 2 CO 3  such that the product electrode active material having the formula Ag 2 V 4 O 11  has a BET surface area of about 0.44 m 2 /g.  
     
     
         13 . The cathode of  claim 9  wherein the metal salt is CuO such that the product electrode active material having the formula Cu 0.2 Ag 0.8 V 2 O 5.6  has a BET surface area of about 0.31 m 2 /g.  
     
     
         14 . A nonaqueous electrochemical cell, comprising: 
 a) an anode;    b) a cathode containing an active material comprising an ε-phase silver vanadium oxide compound characterized as having been prepared from a mixture of a silver vanadium compound and a metal salt forming 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 ;    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.    
     
     
         15 . The electrochemical cell of  claim 14  wherein the anode is comprised of lithium.  
     
     
         16 . The electrochemical cell of  claim 14  wherein the silver vanadium containing compound is γ-phase silver vanadium oxide having the formula Ag 1.2 V 3 O 8.1 .  
     
     
         17 . The electrochemical cell of  claim 14  wherein the metal salt is selected from the group consisting of silver lactate, silver triflate, silver pentafluoropropionate, silver laurate, silver myristate, silver palmitate, silver stearate, silver vanadate, silver oxide, silver carbonate, copper oxide, copper carbonate, manganese carbonate, manganese oxide, magnesium carbonate, magnesium oxide, and combinations and mixtures thereof.  
     
     
         18 . The electrochemical cell of  claim 14  wherein the metal salt is Ag 2 O and the ε-phase silver vanadium oxide has a BET surface area of about 0.54 m 2 /g.  
     
     
         19 . The electrochemical cell of  claim 14  wherein the metal salt is Ag 2 CO 3  and the ε-phase silver vanadium oxide has a BET surface area of about 0.44 m 2 /g.  
     
     
         20 . The electrochemical cell of  claim 14  wherein the reaction mixture is heated to the at least one reaction temperature in a range from about 300° C. to about 550° C.  
     
     
         21 . The electrochemical cell of  claim 14  wherein the reaction mixture is heated to the at least one reaction temperature for about 5 hours to about 30 hours.