TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The redox flow battery further comprises a catholyte tank and an anolyte tank, where each of the catholyte tank and the anolyte tank is in fluid communicated with the cathode cell and the anode cell, respectively. The ion exchange membrane is an anion exchange membrane.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The metal-ligand coordination compound: comprises at least one metal comprising nickel, cobalt, iron, ruthenium, zinc, manganese, yttrium, zirconium, titanium, chromium, magnesium, cerium, copper, lead or vanadium; comprises a nitrogen atom-containing heteroaromatic ligand and/or a nitrogen atom-containing heteroaliphatic ligand; and undergoes a reversible oxidation and reduction reaction.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The nitrogen atom-containing heteroaromatic ligand or the nitrogen atom-containing heteroaliphatic ligand comprises at least one of optionally substituted dipyridyl, optionally substituted terpyridyl, optionally substituted phenanthroline, optionally substituted ethylenediamine, optionally substituted propylenediamine or optionally substituted N-heterocyclic carbene, where each of the each of the substituted dipyridyl, the substituted terpyridyl, the substituted phenanthroline, the substituted ethylenediamine, the substituted propylenediamine and the substituted N-heterocyclic carbene comprises at least one 1-6C alkyl group, a halogen atom, 5-8C alkylphenyl group or a nitro group. The optionally substituted N-heterocyclic carbene is at least one of 2,6-bis(methylimidazole-2-ylidene)pyridine, 1,3-dimesitylimidazole, 1,3-bis(2,5-diisopropylphenyl)imidazole, 1,3-dimethylimidazole, 1,3-di-tert-butylimidazole, 1,3-dicyclohexylimidazole or 1-ethyl-3-methylimidazole. The metal-ligand coordination compound is one of (bis(4,4'-dimethyl-(2,2')bipyridinyl)-(2,2')bipyridinyl)iron(VI) complex, (bis((2,2')bipyridinyl)-5-nitro-(1,10)phenanthroline)iron(VI) complex, or (4'-(4-chloro-phenyl)-(2,2';6',2'')terpyridine-(2,2';6',2'')terpyridine)iron(IV) complex.