Introduction of Electron-Withdrawing Groups in Organic Cathodes for Enhancing the Performance of Air-Charging Aqueous Zinc-Ion Batteries

Developing new self-powered systems with a simple structure for use in poor environments without an external power supply is significant work. Herein, a flexible/coin-type aqueous zinc-ion battery (AZIB) is constructed using the hexacyanohexaazatrinaphthylene (HCHATN) cathode, which can provide the maximum volumetric/mass energy density (7.81 mWh cm–3/120.9 Wh kg–1) and high cycle stability via the insertion and extraction of Zn2+ and H+ together. Intriguingly, the flexible Zn//HCHATN battery not only had excellent flexibility but could also be chemically self-charged through a spontaneous redox reaction between the discharged HCHATN cathode and O2 in air when its energy was exhausted. After 15 h of air-charging, the discharge capacity of the flexible Zn//HCHATN battery could reach 225 mAh g–1 at 0.5 A g–1 with a general self-charging cycle stability (6 cycles), while maintaining 220 mAh g–1 even at 20 A g–1, displaying high-rate capability. Impressively, under different charging modes (galvanostatic or/and chemical charging), the flexible Zn//HCHATN battery can work well, displaying superior reusability. This work provides a design rationale for high-rate, flexible, air-rechargeable AZIBs.