Molecular Tailoring of an n/p-type Phenothiazine Organic Scaffold for Zinc Batteries

The p-type or n-type redox reactions of organics are being used as the reversible electrodes to build the next-generation rechargeable batteries with sustainable and tunable characteristics. However, the n-type organics that store cations generally exhibit low potential (<0.8 V vs. Zn/Zn²⁺ ), while the p-type organics that store anions suffer from limited capacity (<100 mAh g^-1 ). Herein, we demonstrate that bis(phenylamino)phenothiazin-5-ium iodide (PTD-1) containing both n-type and p-type redox moieties exhibits a hybrid charge storage mechanism (n/p-type at low potential, p-type at high potential). Such a hybrid mechanism combines the advantages of n- and p-type reactions and compensates for the associated drawbacks of each. Accordingly, the aqueous Zn//PTD-1 full cell shows a high voltage (1.8 V_maximum or 1.1 V_average ), a high capacity 188.24 mAh g_PTD-1 ^-1 (achieved at 40 mA g^-1 ), a long-life and a supercapacitor-like high power. These results shed new light on the design of advanced organic electrodes.