A quinone derivative with a high redox potential that does not undergo Michael addition or proto-desulfonation. This molecule addresses the key issues faced with the positive side material of an aqueous all-organic flow battery. This new molecule is 2,5-dihydroxy-4,6-dimethylbenzene-1,3-disulfonic acid (or the disulfonate salt thereof). This quinone derivative offers good solubility, electrochemical reversibility, and robustness to charge/discharge cycling. Quinones with reduced crossover are also provided.

A quinone derivative with a high redox potential that does not undergo Michael addition or proto-desulfonation. This molecule addresses the key issues faced with the positive side material of an aqueous all-organic flow battery. This new molecule is 2,5-dihydroxy-4,6-dimethylbenzene-1,3-disulfonic acid (or the disulfonate salt thereof). This quinone derivative offers good solubility, electrochemical reversibility, and robustness to charge/discharge cycling. Quinones with reduced crossover are also provided.

Various embodiments may comprise an ion exchange membrane (IEM) redox flow cell comprising a IEM, a negative electrode in contact with a reactive fluid, a liquid electrolyte comprising reactants, a positive electrode in contact with the liquid electrolyte, and a diffusion barrier layer disposed between the IEM and the positive electrode, and wherein the negative electrode is isolated from the positive electrode by the IEM.

Various embodiments may comprise an ion exchange membrane (IEM) redox flow cell comprising a IEM, a negative electrode in contact with a reactive fluid, a liquid electrolyte comprising reactants, a positive electrode in contact with the liquid electrolyte, and a diffusion barrier layer disposed between the IEM and the positive electrode, and wherein the negative electrode is isolated from the positive electrode by the IEM.

Stable solutions comprising high concentrations of charged coordination complexes, including iron hexacyanides are described, as are methods of preparing and using same in chemical energy storage systems, including flow battery systems. The use of these compositions allows energy storage densities at levels unavailable by other iron hexacyanide systems.

Stable solutions comprising high concentrations of charged coordination complexes, including iron hexacyanides are described, as are methods of preparing and using same in chemical energy storage systems, including flow battery systems. The use of these compositions allows energy storage densities at levels unavailable by other iron hexacyanide systems.

An apparatus comprises an anode formed of graphene oxide from an acidic pH; a cathode from a pH greater than the acidic pH of the anode; and charge collectors deposited on the anode and the cathode. The anode comprises graphene oxide, the graphene oxide comprising an ink and having a pH of about 1 to about 4.

An apparatus comprises an anode formed of graphene oxide from an acidic pH; a cathode from a pH greater than the acidic pH of the anode; and charge collectors deposited on the anode and the cathode. The anode comprises graphene oxide, the graphene oxide comprising an ink and having a pH of about 1 to about 4.

Redox flow battery systems having a supporting solution that contains Cl.sup.− ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO.sub.4.sup.2− and Cl.sup.− ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V.sup.2+ and V.sup.3+ in a supporting solution and a catholyte having V.sup.4+ and V.sup.5+ in a supporting solution. The supporting solution can contain Cl.sup.− ions or a mixture of SO.sub.4.sup.2− and Cl.sup.− ions.

Redox flow battery systems having a supporting solution that contains Cl.sup.− ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO.sub.4.sup.2− and Cl.sup.− ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V.sup.2+ and V.sup.3+ in a supporting solution and a catholyte having V.sup.4+ and V.sup.5+ in a supporting solution. The supporting solution can contain Cl.sup.− ions or a mixture of SO.sub.4.sup.2− and Cl.sup.− ions.