Organic non-aqueous cation-based redox flow batteries

A non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator between the negative and positive electrolytes;

• the negative electrode being positioned within a negative electrolyte chamber (“NE chamber”) defined by a first housing and containing the negative electrolyte, the NE chamber connecting with a first negative electrolyte reservoir (“NE reservoir”) and a second NE reservoir such that the first NE reservoir, the NE chamber, and the second NE reservoir can be placed in fluid-flow communication and collectively define a negative electrolyte circulation pathway;
• a first pump being operably positioned within the negative electrolyte circulation pathway to circulate the negative electrolyte back and forth between the first NE reservoir and the second NE reservoir over the negative electrode;
• the positive electrode being positioned within a positive electrolyte chamber (“PE chamber”) defined by a second housing and containing the positive electrolyte, the PE chamber connecting with a first positive electrolyte reservoir (“PE reservoir”) and a second PE reservoir such that the first PE reservoir, the PE chamber, and the second PE reservoir can be placed in fluid-flow communication and collectively define a positive electrolyte circulation pathway;
• a second pump being positioned within the positive electrolyte circulation pathway to circulate the positive electrolyte back and forth between the first PE reservoir and the second PE reservoir over the positive electrode;
• the negative and positive electrolytes each independently comprising an electrolyte salt, a transition metal-free redox reactant, and optionally an electrochemically stable organic solvent;
• and
• the NE chamber and the PE chamber being separated from one another by the cation-permeable separator, such that cations from the electrolyte salt can flow back and forth between the NE chamber and the PE chamber to balance charges resulting from oxidation and reduction of the redox reactants during charging and discharging of the battery;
• wherein the redox reactant of the positive electrolyte has a higher redox potential than the redox reactant of the negative electrolyte, and the redox reactants are independently selected from the group consisting of an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof;
• the conjugated unsaturated moiety is aromatic, non-aromatic, or a combination thereof;
• and the conjugated unsaturated moiety comprises carbon-carbon unsaturated bonds, carbon-heteroatom unsaturated bonds, or a combination of carbon-carbon and carbon-heteroatom unsaturated bonds;
• the heteroatom of the carbon-heteroatom unsaturated bond is a non-metallic heteroatom or a metalloid heteroatom;
• and wherein the redox reactant of the positive electrolyte comprises a compound selected from:
• (a) a compound of Formula (III):
• in which each of R15, R16, R17, and R18 is F, and each of R19 and R20 independently is alkyl or alkoxyalky;
• and
• (b) a compound of Formula (V):
• in which each of X9, X10, X11, and X12 is F, and each of R21 and R22 independently is alkyl or alkoxyalkyl.