Organic Compound as a Cathode for Aqueous Zinc-Ion Batteries with Improved Electrochemical Performance via Multiple Active Centers

Aqueous zinc-ion batteries (AZIBs) are deemed as an emerging substitute for secondary batteries. The type of cathode material has enormous implications for the performance of AZIBs. Organics can act as a suitable cathode for AZIBs because of their green, adjustable structure and good stability. However, developing promising organics with high performance is still an important challenge. Here, an organic material 8,21dihydronaphtho [2,3-a]naphtha[2 ',3 ':7,8] quinoxalino [2,3-i]phenazine-5,11,16,22-tetraone (DADB) was synthesized and explored as a cathode for AZIBs. Benefiting from the affluent active sites and the expanded conjugated structure, the DADB electrode rendered splendid rate capability (71 mA h g-1 under 5 A g-1) and outstanding cycle lifespan (87% retention over 6000 cycles under 10 A g-1). Moreover, ex situ characterizations proved that C=N and C=O bonds were the electrochemical redox centers for storage of Zn2+. Additionally, the DADB electrode also exhibited excellent electrochemical performance in a gel electrolyte (134 mA h g-1 under 0.05 A g-1). This research offered a mentality for designing high-performance organic cathodes of AZIBs.