Quinones and their derivatives are the basis of many organic redox systems including NARFBs and AORFBs. In one study, 1,2-dihydrobenzoquinone-3,5-disulfonic acid (BQDS) and 1,4-dihydrobenzoquinone-2-sulfonic acid (BQS) were employed as cathodes, and conventional Pb/PbSO4 was the anolyte in an acid AORFB. These first AORFBs are hybrid systems as they use organic redox active materials only for the cathode side. The quinones accepts two units of electrical charge, compared with one in conventional catholyte, implying that such a battery could store twice as much energy in a given volume.