A small molecule phenazine-based cathode materials with H+ storage in mild electrolyte

Abstract

Aqueous zinc-organic batteries using organic cathode materials with resourceful and environmental friendliness have attracted much attention for their sustainability and excellent electrochemical performance. And selectively storing H+ in mild aqueous electrolytes by organic active materials can lead to fast reaction kinetics for zinc-organic batteries, thus providing excellent rate performance. Herein, we have synthesized 2,3,7,8-Tetraamino-phenazine (TAPZ) with four π-conjugated amino groups, CN active sites, and extended aromatic planes, including small energy gap values and accessible electrochemically active centers, as well as good electrical conductivity, enables selective storage of H+ in aqueous electrolytes. In the optimized 3 M ZnSO4 electrolyte, TAPZ demonstrates excellent electrochemical properties as a cathode material, including the high initial discharge specific capacity (238.8 mAh g−1 at 100 mA g−1), a good rate capacity (125.4 mAh g-1 at 3 A g-1), and the long cycle stability (over 3000 cycles at 1 A g-1). In addition, the H+ storage mechanism of TAPZ in mild electrolytes is verified by ex-situ spectroscopic characterization and density functional theory (DFT) calculations.