A Highly Electroactive Poly(aniline-co-thionine) for Rechargeable Zinc Batteries

Abstract

A novel conductive polymer poly(aniline-co-thionine) (PANTHI) was prepared via electrochemical polymerization by introducing redox-active thionine into the polyaniline skeleton to extend its cable length, and then explored as a cathode active material for aqueous zinc-polymer batteries in a mixed solution of ZnCl2 and NH4Cl. Due to that thionine is a phenothiazine derivative without methyl groups, it increases the degree of conjugation of copolymer chains and the Zn-copolymer battery exhibits greatly enhanced discharge specific capacity, energy density, and excellent cycle stability at pH 4.8, compared to Zn-polyaniline batteries. The Zn-PANTHI battery delivers a high specific capacity and energy density of 157.8 Ah kg−1 and 173.6 Wh kg−1, respectively, and retains the coulomb efficiency of about 95.3% over 200 consecutive cycles at a current density of 200 mA g−1. The copolymerization strategy provided an effective method towards synthesizing new conductive aniline-based polymers with other organic redox-active groups for rechargeable batteries, supercapacitors and sensors.

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

“…Accordingly, it becomes the next logical step to explore the multi‐electron p‐type organics, in order to obtain a higher capacity. The phenothiazines and phenazines are typical multi‐electron p‐type organic molecules, which have an electron‐rich nitrogen/sulfur heterocyclic ring [46–52] . In the past few years, phenothiazines and phenazines have been applied as cathode materials for Li‐organic batteries, showing a high capacity (≈150 mAh g −1 ) [48, 53–60] .…”

“…The phenothiazines and phenazines are typical multi-electron p-type organic molecules, which have an electron-rich nitrogen/sulfur heterocyclic ring. [46][47][48][49][50][51][52] In the past few years, phenothiazines and phenazines have been applied as cathode materials for Li-organic batteries, showing a high capacity ( � 150 mAh g À 1 ). [48,[53][54][55][56][57][58][59][60] However, they often exhibit limited cycle stability (< 500 cycles) because of their high solubility in electrolyte.…”