Redox flow battery electrolytes

A redox flow battery comprising:

• a positive electrode;
• a first redox active composition comprising a first redox active compound corresponding in structure to any one of General Formulas (1)-(3), or a mixture thereof as a positive electrode electrolyte, the positive electrode electrolyte contacting the positive electrode;
• a negative electrode;
• a second redox active composition comprising
• (i) a second redox active compound corresponding in structure to any one of General Formulas (1)-(3), or a mixture thereof;
• and/or
• (ii) another second redox active compound selected from the group consisting of a metal, a metal oxide, a metal-ligand coordination compound, bromine, chlorine, iodine, oxygen, an organic dye, a salt thereof, and a mixture thereof as a negative electrode electrolyte, the negative electrode electrolyte contacting the negative electrode;
• and
• a separator interposed between the positive electrode and the negative electrode;
• wherein
• wherein
• R1-R18 is each independently selected from hydrogen;
• hydroxyl;
• carboxy;
• linear or branched, optionally substituted C1-6 alkyl optionally comprising at least one heteroatom selected from N, O and S;
• a carboxylic acid;
• an ester;
• a halogen;
• optionally substituted C1-6 alkoxy;
• optionally substituted amino;
• nitro;
• carbonyl;
• phosphoryl;
• phosphonyl;
• cyanide;
• and sulfonyl;
• and
• wherein at least one of R1-R4 in General Formula (1), at least one of R5-R10 in General Formula (2) and/or at least one of R11-R18 in General Formula (3) of the first redox active compound is a substituted amine selected from —NHR/NH2R+, —NR2/NHR2+ and —NR3+, where R is selected from the group consisting of —CnH2nOH, —CnH2nNH2, —CnH2nNR2, —CnH2nCO2H and —CnH2nSO3H, wherein n is an integer selected from 1, 2, 3, 4, 5 or 6, where R is H or C1-C6 alkyl or substituted C1-C6 alkyl comprising at least one heteroatom selected from N, O and S.