Redox flow secondary battery and electrolyte membrane for redox flow secondary battery

An electrolyte membrane for a redox flow secondary battery, comprising an ion-exchange resin composition comprising a fluorine-based polyelectrolyte polymer having a structure represented by the following formula (1):

• —[CF2—CX1X2]a—[CF2—CF((—O—CF2—CF(CF2X3))b—Oc—(CFR1)d—(CFR2)e—(CF2)f—X4)]g— (1)
• wherein X1, X2, and X3 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups having 1 to 3 carbon atoms;
• X4 represents COOZ, SO3Z, PO3Z2, or PO3HZ wherein Z represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or amines (NH4, NH3R1, NH2R1R2, NHR1R2R3, NR1R2R3R4) wherein R1, R2, R3, and R4 each independently represent one or more selected from the group consisting of alkyl groups and arene groups, when X4 is PO3Z2, Z may be identical or different;
• R1 and R2 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups and fluorochloroalkyl groups having 1 to 10 carbon atoms;
• and a and g represent numbers satisfying 0≦a<1, 0<g≦1, and a+g=1, b represents an integer of 0 to 8, c represents 0 or 1, and d, e, and f each independently represent an integer of 0 to 6 (with the proviso that d, e, and f are not 0 at the same time);
• and
• wherein in a test in which 0.1 g of the fluorine-based polyelectrolyte polymer is immersed in 50 g of a Fenton's reagent solution containing a 3% hydrogen peroxide solution and 200 ppm of divalent iron ions at 40° C. for 16 hours, an amount of fluorine ions eluted detected in a solution is 0.03% or smaller of a whole amount of fluorine in a immersed polymer.

An electrolyte membrane for a redox flow secondary battery, comprising an ion-exchange resin composition comprising a fluorine-based polyelectrolyte polymer having a structure represented by the following formula (1):

• —[CF2—CX1X2]a—[CF2—CF((—O—CF2—CF(CF2X3))b—Oc—(CFR1)d—(CFR2)e—(CF2)f—X4)]g— (1)
• wherein X1, X2, and X3 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups having 1 to 3 carbon atoms;
• X4 represents COOZ, SO3Z, PO3Z2, or PO3HZ wherein Z represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or amines (NH4, NH3R1, NH2R1R2, NHR1R2R3, NR1R2R3R4) wherein R1, R2, R3, and R4 each independently represent one or more selected from the group consisting of alkyl groups and arene groups, when X4 is PO3Z2, Z may be identical or different;
• R1 and R2 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups and fluorochloroalkyl groups having 1 to 10 carbon atoms;
• and a and g represent numbers satisfying 0≦a<1, 0<g≦1, and a+g=1, b represents an integer of 0 to 8, c represents 0 or 1, and d, e, and f each independently represent an integer of 0 to 6 (with the proviso that d, e, and f are not 0 at the same time);
• and
• wherein the ion-exchange resin composition comprises 0.1 to 20 parts by mass of a polyphenylene ether resin and/or a polyphenylene sulfide resin with respect to 100 parts by mass of the fluorine-based polyelectrolyte polymer.

An electrolyte membrane for a redox flow secondary battery, comprising an ion-exchange resin composition comprising a fluorine-based polyelectrolyte polymer having a structure represented by the following formula (1):

• —[CF2—CX1X2]a—[CF2—CF((—O—CF2—CF(CF2X3))b—Oc—(CFR1)d—(CFR2)e—(CF2)f—X4)]g— (1)
• wherein X1, X2, and X3 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups having 1 to 3 carbon atoms;
• X4 represents COOZ, SO3Z, PO3Z2, or PO3HZ wherein Z represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or amines (NH4, NH3R1, NH2R1R2, NHR1R2R3, NR1R2R3R4) wherein R1, R2, R3, and R4 each independently represent one or more selected from the group consisting of alkyl groups and arene groups, when X4 is PO3Z2, Z may be identical or different;
• R1 and R2 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups and fluorochloroalkyl groups having 1 to 10 carbon atoms;
• and a and g represent numbers satisfying 0≦a<1, 0<g≦1, and a+g=1, b represents an integer of 0 to 8, c represents 0 or 1, and d, e, and f each independently represent an integer of 0 to 6 (with the proviso that d, e, and f are not 0 at the same time);
• and
• wherein the ion-exchange resin composition comprises one or more selected from the group consisting of a Ce-based additive, a Co-based additive, and a Mn-based additive.

A redox flow secondary battery comprising an electrolytic bath comprising:

• a positive electrode cell chamber comprising a positive electrode composed of a carbon electrode;
• a negative electrode cell chamber comprising a negative electrode composed of a carbon electrode;
• and
• an electrolyte membrane as a separation membrane to separate the positive electrode cell chamber and the negative electrode cell chamber,
• wherein the positive electrode cell chamber comprises a positive electrode electrolyte solution comprising a positive electrode active substance;
• and the negative electrode cell chamber comprises a negative electrode electrolyte solution comprising a negative electrode active substance;
• wherein the redox flow secondary battery charges and discharges based on changes in valences of the positive electrode active substance and the negative electrode active substance in the electrolyte solutions;
• wherein the electrolyte membrane comprises an ion-exchange resin composition comprising a fluorine-based polyelectrolyte polymer having a structure represented by the following formula (1):
• —[CF2—CX1X2]a—[CF2—CF((—O—CF2—CF(CF2X3))b—Oc—(CFR1)d—(CFR2)e—(CF2)f—X4)]g— (1)
• wherein X1, X2, and X3 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups having 1 to 3 carbon atoms;
• X4 represents COOZ, SO3Z, PO3Z2, or PO3HZ wherein Z represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or amines (NH4, NH3R1, NH2R1R2, NHR1R2R3, NR1R2R3R4) wherein R1, R2, R3, and R4 each independently represent one or more selected from the group consisting of alkyl groups and arene groups, when X4 is PO3Z2, Z may be identical or different;
• R1 and R2 each independently represent one or more selected from the group consisting of halogen atoms and perfluoroalkyl groups and fluorochloroalkyl groups having 1 to 10 carbon atoms;
• and a and g represent numbers satisfying 0≦a<1, 0<g≦1, and a+g=1, b represents an integer of 0 to 8, c represents 0 or 1, and d, e, and f each independently represent an integer of 0 to 6 (with the proviso that d, e, and f are not 0 at the same time);
• and
• wherein in a test in which 0.1 g of the fluorine-based polyelectrolyte polymer is immersed in 50 g of a Fenton's reagent solution containing a 3% hydrogen peroxide solution and 200 ppm of divalent iron ions at 40° C. for 16 hours, an amount of fluorine ions eluted detected in a solution is 0.03% or smaller of a whole amount of fluorine in a immersed polymer.