Molecular Tailoring of p-type Organics for Zinc Batteries with High Energy Density.

P-type organic electrode materials are known for their high redox voltages and fast kinetics. However, single-electron p-type organic materials generally exhibit low capacity despite high operating voltage and stability, while some multi-electron p-type organic materials have high theoretical capacity but low stability. To address this challenge, we explore the possibility of combining single-electron and multi-electron units to create high-capacity and stable p-type organic electrodes. We demonstrate the design of a new molecule, 4, 4'-(10H-phenothiazine-3, 7-diyl) bis (N, N-diphenylaniline) (PTZAN), which is created by coupling the triphenylamine molecule and the phenothiazine molecule. The resulting PTZAN//Zn battery shows excellent stability (2,000 cycles), high voltage (1.3 V), high capacity (145 mAh g-1), and energy density of 187.2 Wh kg-1. Theoretical calculations and in/ex-situ analysis reveal that the charge storage of the PTZAN electrode is mainly driven by the redox of phenothiazine heterocycles and triphenylamine unit, accompanied by the combination/release of anions and Zn2+.