Inexpensive metal-free organic redox flow battery (orbat) for grid-scale storage

A flow battery comprising:

• a positive electrode;
• a positive electrode electrolyte including water and a first quinone redox couple, the first quinone redox couple including a first quinone and a first hydroquinone, the first quinone being reduced to the first hydroquinone during discharge, the first quinone selected from the group consisting of benzoquinone and benzoquinones that are substituted with an electron withdrawing group;
• a negative electrode;
• a negative electrode electrolyte flowing over and contacting the negative electrode;
• and
• a polymer electrolyte membrane interposed between the positive electrode and the negative electrode.

A flow battery comprising:

• a positive electrode;
• a positive electrode electrolyte flowing over and contacting the positive electrode;
• a negative electrode;
• a negative electrode electrolyte including water and a quinone redox couple, the negative electrode electrolyte flowing over and contacting the positive electrode, the quinone redox couple including a quinone and a hydroquinone, the hydroquinone being oxidized to the quinone during discharge, the quinone including a component selected from the group consisting of anthraquinone and anthraquinone that are substituted with an electron donating group;
• and
• a polymer electrolyte membrane interposed between the positive electrode and the negative electrode.