posted on 2018-05-18, 00:00authored byXingwen Yu, Arumugam Manthiram
Organic
electrode materials such as quinones are drawing rising
attention as promising redox-active materials for the development
of rechargeable batteries. In aqueous solutions, the redox potential
of quinones is dependent on the alkalinity and acidity of the medium.
Under an alkaline condition, the oxidation potential of hydroquinone
(existing as diphenolate) is ca. 0.8 V lower than that under an acidic
condition. On the other hand, under an acidic condition, the reduction
potential of oxygen is ca. 0.8 V higher than that under an alkaline
condition. By taking these advantages, a quinone–air cell with
a rational voltage is strategically demonstrated with an alkaline
anode electrolyte and an acidic cathode electrolyte, which are physically
separated by a Na+-ion conductive solid-state electrolyte
membrane. The Na+-ions shuttling through the solid-state
membrane act as ionic mediators/messengers to sustain and link the
redox reactions at the two electrodes.