Enhancing the Electrochemical Performance of Small Quinone Organic Electrode via High-Concentration Zn/K Hybrid Electrolyte for Aqueous Batteries.

Small Quinone-based Organic Electrodes have received extensive attention. However, the rapid dissolution of small quinone electrode into electrolyte impede their practical applications. For example, Anthraquinone (AQ) and Phenanthrenequinone (PQ) molecules have been rarely reported for aqueous batteries due to the inferior electrochemical performance. Herein, a high-concentration hybrid electrolyte containing 1m Zn(OTF) and 15m KOTF salts is introduced for small quinone electrode and investigate the redox behavior of PQ and AQ electrode is investigated in Zn/K hybrid electrolyte. These findings reveal that AQ with carbonyl groups at para-position selectively stores proton rather than K, while PQ with carbonyl group at ortho-position simultaneously stores proton and K without selectivity. Moreover, the Zn(OTF) salt serves as both proton buffer and binder to improve the cycle stability. Consequently, when PQ is paired with Zn metal anode for Zn || PQ batteries, the addition of potassium salt can improve the energy density of the Zn batteries. Moreover, when PQ is paired with Prussian blue cathode to assemble aqueous K-ion batteries, the addition of zinc salt in the electrolyte can improve the cycle stability via binding discharged PQ molecules with divalent-ions. This research provides an electrolyte engineering strategy to address the challenges facing PQ electrode for aqueous batteries.