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

Abstract

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 8,21-dihydronaphtho[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.