An Ultra-Stable 2D Linear Polymer Cathode for High-Performance Aqueous Zinc-Organic Batteries

Abstract

Two-dimensional structure of cathode materials possesses fast kinetics in aqueous zinc ion batteries. However, in organic linear polymers it is rare to form two-dimensional structures due to the bond rotations of the polymerization reaction. In this work, inspired by the process of forming carbon fibers from polyacrylonitrile, a novel two-dimensional linear polymer (2DLP) of poly(2H,11H-bis[l,4]triazino[3,2-b : 3′,2′-m]triphenodithiazine-3,12-diyl-2,11-diyli-dene-11,12-bis[methyldene]) (PTL) cathode materials were prepared for aqueous zinc-ion battery cathode materials by designing ladder structure polymer molecules with highly restricted bond rotations. PTL possess fast cations diffusion (4.27×10⁻⁷ cm⁻¹ s⁻¹) due to its layered structure. Moreover, the PTL electrodes exhibit an ultra-long cycle stability (7000 cycles still remain 87 % capacity remains). Meanwhile, as PTL mass loading increase from 3.13 to 6.27 mg cm⁻², the specific capacity kept 98 % retention after 100 cycles. Besides, the assembled Zn/PTL flexible pack battery exhibits a 6.6 mAh capacity at 0.5 A g⁻¹. Furthermore, though a range of ex site analysis, it was supported that the charge storage mechanism of PTL is driven by the imine moiety, and accompanies by the insertion and extraction of Zn²⁺/H⁺ ions. This work attempts to provide a new sight of improve the poor ion diffusion coefficient of organic materials.