Perfluorinated Membranes and Improved Electrolytes for Redox Cells and Batteries

• US 20080292964A1
• Filed: 06/19/2006
• Published: 11/27/2008
• Est. Priority Date: 06/20/2005
• Status: Active Grant

• Current Assignee: NewSouth Innovations Pty Limited (University Of New South Wales)
• Original Assignee: NewSouth Innovations Pty Limited (University Of New South Wales)
• Inventors: Kazacos, Nicholas Michael, Kazacos, George Christopher
• Granted Patent: US 8,541,138 B2
• Time in Patent Office: Days
• US Class Current: 429/231.5
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 50/64 Constructional details of batteries specially adapted for electric vehicles
• CPC Class Codes: H01M 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 8/1023 having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
• CPC Class Codes: H01M 8/1067 characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
• CPC Class Codes: H01M 8/1081 starting from solutions, dispersions or slurries exclusively of polymers
• CPC Class Codes: H01M 8/1088 Chemical modification, e.g. sulfonation
• CPC Class Codes: H01M 8/109 thermal other than drying, e.g. sintering
• CPC Class Codes: H01M 8/188 by recharging of redox couples containing fluids; Redox flow type batteries
• CPC Class Codes: H01M 8/20 Indirect fuel cells, e.g. fuel cells with redox couple being irreversible H01M8/18 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/50 Fuel cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A vanadium redox cell having a positive half cell containing a positive half cell solution comprising a supporting electrolyte selected from H₂SO₄, HBr/HCl mixtures and one or more ions selected from the group vanadium (EI), Vanadium (IV), Vanadium (V), Br₃ and Br₂Cl; a negative half cell containing a negative half cell solution comprising a supporting electrolyte selected from H₂SO₄, HBr and HBr/HCl mixtures and one or more vanadium ions selected from the group Vanadium (II), Vanadium (III) and Vanadium (FV) and a perfluorinated cast cation exchange membrane or separator disposed between the positive and negative half cells and in contact with the positive and negative half cell solutions.

Claims

1-94. -94. (canceled)

95. A redox cell having a positive half cell, a negative half cell, a positive half cell solution and a negative half cell solution further comprising:

a perfluorinated ionically conducting membrane located between the positive half cell and the negative half cell and in contact with the positive half cell solution and the negative half cell solution wherein the membrane is a cast cation exchange membrane.

97. The redox cell according to claim 95 wherein the cast perfluorinated cation exchange membrane includes a polymer selected from the group consisting of a PTFE, perfluorosulfonic acid and a perfluorosulphonic acid/PTFE copolymer.

98. The redox cell according to claim 97 wherein the cast perfluorinated membrane has a thickness of between 0.5 and 5 mil, an acid capacity of between 0.5 and 2 mmol/g, a conductivity at 25°

C. of between 0.01 and 1 S/cm, a water uptake of between 30% and 70% at 100°

C. for 1 hour, a tensile strength of between 20 and 60 MPa and a melting point ranging from 180 to 240°

C.

99. The redox cell according to claim 98 wherein the perfluorinated membrane is produced by casting from a solution of a resin selected from a group consisting of a resin that has an Equivalent Weight (EW) of between 800 and 1100 grams resin per equivalent SO₃⁻

, a resin that has an Equivalent Weight (EW) of substantially 1032 grams resin per equivalent SO₃⁻

, a resin that has an ion exchange capacity (1/EW) of between 1.25 and 0.91 milliequivalents SO₃⁻

per gram resin wherein in use the milliequivalents are typically 0.97 milliequivlanents SO₃⁻

per gram resin.

100. The redox cell of according to claim 99 wherein micro particles are added to the membrane to increase water uptake and conductivity as well as to decrease linear expansion of the membrane.

101. The redox cell according to claim 95 wherein the membrane is treated prior to use in the redox cell.

102. The redox cell according to claim 95 wherein the membrane is treated prior to use by a method comprising the step of soaking the membrane in an aqueous solution selected from the group consisting of hydrogen peroxide, HCl, NaOH and sulphuric acid to reduce resistivity of the membrane and enhance voltage efficiency during charge-discharge cycling.

103. The redox cell according to claim 102 wherein the membrane is treated at above room temperature prior to use.

104. The redox cell according to claim 103 wherein the membrane is treated in boiling water prior to use.

108. The redox cell according to claim 95 wherein the membrane has a linear expansion selected from the group consisting of less than 8%, less than 5% and less than 3% in both directions from 50% Relative Humidity at 23°

C. to water soaked at 23°

C. and isotropic swelling and tensile strength properties.

109. The redox cell according to claim 108 wherein the membrane is produced by casting from a solution of a resin that has an Equivalent Weight (EW) selected from the group consisting of 800 to 1100 grams resin per equivalent SO₃⁻

and 1032 grams resin per equivalent SO₃⁻

and an ion exchange capacity selected from the group consisting of 1.25 to 0.91 milliequivalents SO₃⁻

per gram resin and 0.97 milliequivlanents SO₃⁻

per gram resin.

110. The redox cell according to claim 109 wherein micro particles are added to the membrane to increase the water uptake and conductivity as well as decrease the linear expansion of the membrane.

111. A redox cell having a positive half cell, a negative half cell, a positive half cell solution and a negative half cell solution further comprising:

a perfluorinated ionically conducting membrane located between the positive half cell and the negative half cell and in contact with the positive half cell solution and the negative half cell solution wherein the membrane has a thickness of between 0.5 to 5 mil;

an acid capacity of between 0.5 and 2 meq/g;

a conductivity at 25°

C. of between 0.01 and 1 S/cm;

a water uptake of between 30% and 70% at 100°

C. for 1 hour;

a tensile strength of between 20 and 60 MPa in both directions when water soaked at 23°

C.;

a linear expansion of less than 8% from 50% Relative Humidity at 23°

C. to water soaked at 23°

C. in both directions;

a melting point ranging from 180 to 240°

C., wherein the perfluorinated membrane is produced by casting from a solution of a resin selected from a group consisting of a resin that has an Equivalent Weight (EW) of between 800 and 1100 grams resin per equivalent SO₃⁻

and a resin having an ion exchange capacity of between 1.25 and 0.91 milliequivalents SO₃⁻

per gram resin.

112. The redox cell of claim 111 wherein the positive half cell solution includes a first supporting electrolyte selected from the group consisting of H₂SO₄, HBr and HBr/HCl mixtures and at least one vanadium ion selected from the group consisting of vanadium (III), vanadium (IV) and vanadium (V);

and wherein the negative half cell solution includes a second supporting electrolyte selected from the group consisting of H₂SO₄, HBr and HBr/HCl mixtures and at least one vanadium ion selected from the group consisting of vanadium (II), vanadium (III) and vanadium (IV).

113. The redox cell of claim 112 wherein the perfluorinated membrane is treated prior to use by soaking the membrane in an aqueous solution selected from the group consisting of hydrogen peroxide, HCl, NaOH and sulphuric acid to reduce resistivity of the membrane and enhance voltage efficiency during charge-discharge cycling.

114. The redox cell according to claim 113 wherein the membrane is treated in boiling water prior to use.