Crossover resistant materials for aqueous organic redox flow batteries

A flow battery comprising:

• a positive electrode;
• a positive electrode electrolyte including water and a first redox couple, the positive electrode electrolyte flowing over and contacting the positive electrode, the first redox couple including a first organic compound Q1 and a reduction product H2Q1 of the first organic compound;
• a negative electrode;
• a negative electrode electrolyte including water and a second redox couple, the negative electrode electrolyte flowing over and contacting the positive electrode;
• and
• an ion exchange membrane interposed between the positive electrode and the negative electrode, wherein the first organic compound has formulae 6 or 7:
• wherein i and k are each independently 0, 1, or 2;
• R13 and R14 are each independently —H, —R′, —NO2, —NH2, —N(R′R″)2, —N(R′R″R′″)3+L−, —CF3, —CCl3, —CN, —SO3H, —PO3H2, —COOH, —CO2R′, —COR′, —CHO, —OH, —OR′, —O−M+, —SO3−M+, —PO3−M+, —COO−M+, —CF2H, —CF2R′, —CFH3, and —CFR′R″ where R′, R″ and R′″ are alkyl or aryl groups;
• Y is —(CH2)n, —(CH2OCH2)n, SO, SO2, other substituted C1-12 alkyl chains which may contain double bonds or triple bonds;
• n is 1, 2, 3, 4, or 5;
• L is a negatively charged counter ion;
• and
• M is a positively charged counter ion.

A flow battery comprising:

• a positive electrode;
• a positive electrode electrolyte including water and a first redox couple, the positive electrode electrolyte flowing over and contacting the positive electrode, the first redox couple including a first organic compound Q1 and a reduction product H2Q1 of the first organic compound;
• a negative electrode;
• a negative electrode electrolyte including water and a second redox couple, the negative electrode electrolyte flowing over and contacting the positive electrode;
• and
• an ion exchange membrane interposed between the positive electrode and the negative electrode, wherein the first organic compound has formulae 8 and 9:
• wherein a and b are each independently 0, 1, 2, or 3;
• R15, R16, R17 and R18 are each independently —H, —R′, —NO2, —NH2, —N(R′R″)2, —N(R′R″R′″)3+L−, —CF3, —CCl3, —CN, —SO3H, —PO3H2, —COOH, —CO2R′, —COR′, —CHO, —OH, —OR′, —O−M+, —SO3−M+, —PO3−M+, —COO−M+, —CF2H, —CF2R′, —CFH3, and —CFR′R″ where R′, R″ and R′″ are alkyl or aryl groups;
• X is —(CH2)n, —(CH2OCH2)n, SO, SO2, other substituted C1-12 alkyl chains which may contain double bonds or triple bonds;
• L is a negatively charged counter ion;
• and
• M is a positively charged counter ion.