Novel vanadium halide redox flow battery

Abstract

A prior to charge vanadium halide redox cell, a vanadium halide redox cell which is at a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge and vanadium halide redox cell which are fully charged and partially charged are described. The prior to charge vanadium halide redox cell comprises a positive half cell containing a positive half cell solution comprising a halide electrolyte, vanadium (III) halide and vanadium (IV) halide, a negative half cell containing a negative half cell solution comprising a halide electrolyte, vanadium (III) halide and vanadium (N) halide wherein the amounts of vanadium (III) halide, vanadium (IV) halide and halide ions in the positive and negative half cell solutions are such that in a first charging step comprising charging the prior to charge vanadium halide redox cell, a vanadium halide redox cell having a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge comprising predominantly vanadium (N) halide in the positive half cell solution and predominantly V(III) halide in the negative half cell solution can be prepared. The vanadium halide redox cell which is at a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge comprises a positive half cell containing a positive half cell solution comprising a halide electrolyte and a vanadium halide which is predominantly vanadium (N) halide, a negative half cell containing a negative half cell solution comprising a halide electrolyte and a vanadium halide which is predominantly vanadium (III) halide wherein the amount of vanadium (N) halide in the positive half cell solution and the amount of vanadium (III) halide in the negative half cell solution are such that the vanadium halide redox cell is at a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge. The vanadium halide redox cell which is fully charged comprises a positive half cell containing a positive half cell solution comprising a halide electrolyte, a polyhalide complex, vanadium (IV) halide and vanadium (V) halide, a negative half cell containing a negative half cell solution comprising a halide electrolyte and vanadium (II) halide wherein the molar concentration of vanadium (V) and polyhalide complex:molar concentration of vanadium (II) halide is about stoichiometrically balanced. The vanadium halide redox cell which is partially charged comprises a positive half cell containing a positive half cell solution comprising a halide electrolyte, a polyhalide complex, vanadium (IV) halide and vanadium (V) halide, a negative half cell containing a negative half cell solution comprising a halide electrolyte, vanadium (II) halide and vanadium (III) halide wherein the number of moles of moles of polyhalide complex and vanadium (V): number of moles of vanadium (II) halide is about stoichiometrically balanced.

1 . A prior to charge vanadium halide redox cell comprising: 
 a positive half cell containing a positive half cell solution comprising a halide electrolyte, vanadium (III) halide and vanadium (IV) halide;    a negative half cell containing a negative half cell solution comprising a halide electrolyte, vanadium (III) halide and vanadium (IV) halide;    wherein the amounts of vanadium (III) halide, vanadium (IV) halide and halide ions in the positive and negative half cell solutions are such:    that in a first charging step comprising charging the prior to charge vanadium halide redox cell, a vanadium halide redox cell having a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge comprising predominantly vanadium (IV) halide in the positive half cell solution and predominantly V(III) halide in the negative half cell solution can be prepared.    
     
     
         2 . The prior to charge vanadium halide redox cell of  claim 1  wherein the amounts of vanadium (III) halide, vanadium (IV) halide and halide ions in the positive and negative half cell solutions are such: 
 that in a second charging step comprising charging the zero state of charge vanadium halide redox cell, a charged vanadium halide redox cell comprising a polyhalide complex in the positive half cell solution and vanadium (II) halide in the negative half cell solution can be prepared.    
     
     
         3 . A prior to charge vanadium halide redox cell according to  claim 1  wherein the positive half cell solution comprises vanadium (III) halide and vanadium (IV) halide in a V(III):V(IV) molar ratio of from about 0.9:1 to about 6:1 in the halide electrolyte; and 
 the negative half cell solution comprises vanadium (III) halide and vanadium (IV) halide in a V(III):V(IV) molar ratio of from about 0.9:1 to about 6:1; and    wherein the volume of the negative half cell solution:the volume of the positive half cell solution is equal to or about equal to the V(III):V(IV) molar ratio.    
     
     
         4 . A prior to charge vanadium halide redox cell according to  claim 3  wherein the positive and negative half cell solutions comprise vanadium (III) halide and vanadium (IV) halide in a V(III):V(IV) molar ratio of about 1:1 and wherein the volume of the negative half cell solution:the volume of the positive half cell solution is about 1:1.  
     
     
         5 . A prior to charge vanadium halide redox cell according to  claim 3  wherein the positive and negative half cell solutions comprise vanadium (III) halide and vanadium (IV) halide in a V(III):V(IV) molar ratio of about 2:1 and wherein the volume of the negative half cell solution:the volume of the positive half cell solution is about 2:1.  
     
     
         6 . A prior to charge vanadium halide redox cell according to  claim 1  wherein the total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         7 . A prior to charge vanadium halide redox cell according to  claim 1  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride.  
     
     
         8 . A prior to charge vanadium halide redox cell according to  claim 1  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride and where the concentration of bromide ions is greater than the concentration of chloride ions and wherein the total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         9 . A vanadium halide redox cell which is at a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge comprising: 
 a positive half cell containing a positive half cell solution comprising a halide electrolyte and a vanadium halide which is predominantly vanadium (IV) halide;    a negative half cell containing a negative half cell solution comprising a halide electrolyte and a vanadium halide which is predominantly vanadium (III) halide;    wherein the amount of vanadium (IV) halide in the positive half cell solution and the amount of vanadium (III) halide in the negative half cell solution are such that the vanadium halide redox cell is at a state of charge selected from the group consisting of a zero state of charge and a near zero state of charge.    
     
     
         10 . The vanadium halide redox cell of  claim 9  wherein total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         11 . The vanadium halide redox cell of  claim 9  wherein the positive half cell solution does not include a significant amount of polyhalide complex at zero state of charge or near zero state of charge.  
     
     
         12 . A vanadium halide redox cell according to  claim 9  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride.  
     
     
         13 . A vanadium halide redox cell according to  claim 9  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride and where the concentration of bromide ions is greater than the concentration of chloride ions and wherein the total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         14 . A vanadium halide redox cell which is fully charged comprising: 
 a positive half cell containing a positive half cell solution comprising a halide electrolyte, a polyhalide complex, vanadium (IV) halide and vanadium (V) halide;    a negative half cell containing a negative half cell solution comprising a halide electrolyte and vanadium (II) halide;    wherein the molar concentration of vanadium (V) and polyhalide complex:molar concentration of vanadium (II) halide is about stoichiometrically balanced.    
     
     
         15 . The vanadium halide redox cell of  claim 14  wherein the number of moles of polyhalide complex:the number of moles of vanadium (II) halide is about 1:2.  
     
     
         16 . The vanadium halide redox cell of  claim 14  wherein the number of moles of polyhalide complex:the number of moles of vanadium (II) halide is in the range of from about 0.7:2 to about 1.3:2.  
     
     
         17 . A vanadium halide redox cell according to  claim 14  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride.  
     
     
         18 . A vanadium halide redox cell according to  claim 14  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride and where the concentration of bromide ions is greater than the concentration of chloride ions and wherein the total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         19 . A vanadium halide redox cell which is partially charged comprising: 
 a positive half cell containing a positive half cell solution comprising a halide electrolyte, a polyhalide complex, vanadium (IV) halide and vanadium (V) halide;    a negative half cell containing a negative half cell solution comprising a halide electrolyte, vanadium (II) halide and vanadium (III) halide;    wherein the number of moles of polyhalide complex and vanadium (V):number of moles of vanadium (II) halide is about stoichiometrically balanced.    
     
     
         20 . The vanadium halide redox cell of  claim 19  wherein the number of moles of polyhalide complex: the number of moles of vanadium (II) halide is about 1:2.  
     
     
         21 . The vanadium halide redox cell of  claim 19  wherein the number of moles of polyhalide complex:the number of moles of vanadium (II) halide is in the range of from about 0.7:2 to about 1.3:2.  
     
     
         22 . A vanadium halide redox cell according to  claim 19  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride.  
     
     
         23 . A vanadium halide redox cell according to  claim 19  wherein the halide is selected from the group consisting of bromide and a combination of bromide and chloride and where the concentration of bromide ions is greater than the concentration of chloride ions and wherein the total halide ion concentration is at least 3 times the total vanadium ion concentration.  
     
     
         24 . A vanadium halide redox cell according to  claim 1 ,  9 ,  14  or  19  wherein the halide comprises bromide and the halide electrolyte also contains a complexing agent for bromine.  
     
     
         25 . A vanadium halide redox cell according to  claim 1 ,  9 ,  14  or  19  wherein the halide electrolyte is immobilised or gelled.  
     
     
         26 . (canceled)  
     
     
         27 . A method for producing an electrolyte for a vanadium halide redox cell comprising: 
 dissolving a V(III) compound and a V(V) compound in a 3:1 molar ratio in a solution of HBr, LiBr, NaBr, KBr or mixtures thereof to produce an approximately 50:50 mixture of V(III) and V(IV) ions in the solution.    
     
     
         28 . The method of  claim 27  where the V(III) compound is V 2 O 3  and the V(V) compound is V 2 O 5 .  
     
     
         29 . A method for producing an electrolyte for a vanadium halide redox cell comprising: 
 dissolving equimolar amounts of a V(III) compound and a V(IV) compound in a solution of HBr, LiBr, NaBr, KBr or mixtures thereof to produce an approximately 50:50 mixture of V(III) and V(IV) ions.    
     
     
         30 . The method of  claim 29  where the V(III) compound is V 2 O 3  and the V(IV) compound is V 2 O 4 .  
     
     
         31 . The method of  claim 27  in which the solution also contains chloride ions.  
     
     
         32 . A method for producing an electrolyte for a vanadium halide redox cell comprising: 
 dissolving a V(III) compound and a V(V) compound in a 4.5:1 molar ratio in a solution of HBr, LiBr, NaBr, KBr or mixtures thereof to produce a 2:1 mixture of V(III) and V(IV) ions.    
     
     
         33 . The method of  claim 32  where the V(III) compound is V 2 O 3  and the V(V) compound is V 2 O 5 .  
     
     
         34 . A method for producing an electrolyte for a vanadium halide redox cell comprising: 
 dissolving a 2:1 molar ratio of a V(III) compound and a V(IV) compound in a solution of HBr, LiBr, NaBr, KBr or mixtures thereof to produce a 2:1 mixture of V(III) and V(IV) ions.    
     
     
         35 . The method of  claim 34  where the V(III) compound is V 2 O 3  and the V(IV) compound is V 2 O 4 .  
     
     
         36 . The method of  claim 27  wherein the total vanadium ion concentration is between 0.5 and 5 M and the total bromide ion concentration is between 2 and 12 M.  
     
     
         37 . The method of  claim 27  wherein the electrolyte is HBr and the total bromide ion concentration is 2 to 12 M.  
     
     
         38 . The method of  claim 27  in which the solution also contains chloride ions at a concentration of 0.5 to 3 M.