Towards High-Performance Aqueous Zinc Batteries via a Semi-Conductive Bipolar-Type Polymer Cathode.

Aqueous Zn-organic batteries have received considerable attention owing to their green, low-cost and high safe nature. Unfortunately, organic materials generally exhibit insulator nature (≈10 -10  S cm -1 ), and most of reported promising performances of Zn-organic batteries are achieved with a low mass-loading (≈2 mg cm -2 ) in cathode, which is far away from practical application (10 mg cm -2 ). Herein, we demonstrate a semi-conductive polymer poly(1,8-diaminonaphthalene) (PDAN) cathode material for Zn batteries, which shows a moderate electronic conductivity (5.9×10 -5  S cm -1 ). Theoretical calculations and in situ/ex situ analysis reveal that the cathode involves a bipolar-type charge storage mechanism. Accordingly, the Zn//PDAN cell exhibits a promising capacity (140 mAh g -1 at 0.1 A g -1 ) and a remarkable cycle stability (1000 cycles without capacity fading) at a high mass-loading (10 mg cm -2 ). These encouraging results shed light on the design of advanced organic electrode.