Molecular Engineering of N-heteroaromatic Organic Cathode for High-Voltage and Highly Stable Zinc Batteries

Abstract

Zinc batteries hold promise for grid-scale energy storage due to their safety and low cost. A key challenge for the field is identifying cathode materials that can undergo reversible redox reactions at the extreme potentials required for realizing high energy density devices. While organic materials have been extensively explored as cathode materials due to their structural tunability and eco-friendliness, most reported zinc-organic batteries exhibit a voltage lower than 1.2 V. In this report, by employing rational molecular design and synthesis, computational analysis, and electrochemical evaluation, the well-studied neutral p-type N-centered is redesigned, triphenylamine organic cathode by replacing three phenyl rings with the smallest aromatic system – cationic cyclopropenium. This results in a novel class of cathode materials with simultaneously enhanced potential, capacity, and stability. The resultant full battery exhibits a high discharge voltage of 1.7 V and an outstanding capacity retention of 95% after 10000 cycles at a discharge capacity of 157.5 mAh g⁻¹cation (103.9 mAh g⁻¹salt).