Oxidized sulfur heterocycles for non-aqueous redox fl0w batteries

A composition comprising:

• a symmetric electroactive redox molecule with at least 2 reversible reactions separated by at least 3.0 V, wherein the symmetric electroactive redox molecule comprises an anolyte moiety comprising a multi-ring conjugated system comprising at least one sulfone group;
• and
• a supporting electrolyte dissolved in a solvent.

A method of synthesizing a redox active sulfone from a sulfur-containing heterocycle comprising:

• reacting the sulfur-containing heterocycle with an acid and an oxidizing agent to form products comprising an oxidized sulfone, wherein the oxidizing agent comprises at least one oxidizing agent selected from the group consisting of aqueous hydrogen peroxide, oxygen, ozone, oxones, potassium chlorate, potassium perchlorate, peroxydisulfuring acid, peroxymonosulfuric acid, hypochlorite, chlorite, chlorate, perchlorate and other halogen analogs, perborates, permanganate, chromate, dichromate or nitric acid, cerium (IV) containing compounds, chromium (VI) containing compounds, vanadium (V) containing compounds, an iron (VI) containing compound, and any combinations thereof;
• and
• separating the products from unreacted portions of the acid and the oxidizing agent, wherein the products comprising the oxidized sulfone is a redox-active molecule with at least one electrochemically reversible reaction at a cell potential less than −1.5 V.