An organic cathode integrating carbonyl and imino groups for high-performance aqueous zinc-ion battery with air self-charging ability

Air-self-charging aqueous zinc-ion batteries (AZIBs) are a promising system applied in some special occasions, where no external power source can be provided to recharge the battery. Here, a new π-conjugated aromatic compound 2,7,12-tri(4H-1,2,4-triazol-4-yl)-1H-pyrrolo [3,4-b]pyrrolo[3′,4′:5,6]pyrazino[2,3 f ]pyrrolo[3′,4′:5,6]pyrazi-no[2,3− h ]quinoxaline-1,3,6,8,11,13(2H,7H,12H)-hexaone (THQH) is reported. Because THQH contains multiple redox-active groups (C N and C O) and its insolubility in 2 M ZnSO 4 , as the cathode material of flexible/coin-type AZIBs, it owns outstanding discharge specific capacity, higher-rate performance and longer cycle life. Various ex-situ experiments and theoretical calculation revealed H + and Zn 2+ participated in the THQH cathode reaction. Notably, as the discharged flexible Zn//THQH battery is exposed to air, it can be self-recharged via the redox reaction between oxygen in air and the discharged THQH cathode, along with H + ions removal. The flexible Zn//THQH battery can deliver a discharge capacity of up to 566 mA h g −1 at 0.5 A g −1 , a higher-rate capability and an excellent self-charging cycle stability (31 cycles) after exposed to air for 28 h, displaying an excellent reusability. This work paves a way for the development of high-performance flexible air self-charging AZIBs. A flexible aqueous zinc-ion battery based on THQH cathode is developed, which not only exhibits higher volumetric specific volume and excellent mechanical flexibility, but also excellent air-recharging capability. • A new π-conjugated aromatic compound THQH was synthesized. • Aqueous Zn//THQH battery based on THQH cathode delivers high discharge specific capacity. • The co-insertion/co-removal of Zn 2+ and H + happen in THQH cathode reaction process. • The flexible Zn//THQH battery has a higher volume energy density and good mechanical flexibility. • The energy exhausted flexible Zn//THQH battery can be air-charged via O 2 in air.