Intermixed Cation-Anion Aqueous Battery Based on an Extremely Fast and Long-Cycling Di-Block Bipyridinium-Naphthalene Diimide Oligomer

TL;DR

This paper introduces a novel organic aqueous battery with a di-block oligomer electrode, demonstrating fast kinetics, high capacity, and long cycle life, suitable for sustainable energy storage in neutral electrolytes including ocean water.

Contribution

The study presents a new di-block oligomer electrode with intermixed p/n-type storage, enabling high capacity, fast cycling, and operation in neutral aqueous electrolytes, including raw ocean water.

Findings

Achieved up to 105 mAh/g capacity with long cycle life (~6500 cycles).

Demonstrated fast kinetics with nearly 60 mAh/g capacity without additives.

Validated full cell performance with ~40 Wh/kg energy density over 1600 cycles.

Abstract

Aqueous batteries, particularly those integrating organic active materials functioning in a neutral pH environment, stand out as highly promising contenders in the stationary electrochemical storage domain, owing to their unparalleled safety, sustainability and low-cost materials. Herein, a novel di-block oligomer (DNVBr), serving as the negative electrode of an all-organic aqueous battery, is shown to offer exceptional output capabilities. The battery's performance is further enhanced by a unique intermixed p/n-type storage mechanism, which is able to simultaneously exchange light and naturally abundant Na+, Mg2+ and Cl-. Reaching up to 105 mAh/g, this system shows remarkable capacity retention for several thousand cycles (6500 cycles, ~40 days) in various neutral electrolytes, including raw ocean water (~3000 cycles, ~75 days). The surprisingly fast kinetics of this di-block oligomer allow to attain an unmatched specific capacity of near to 60mAh/g electrode while entirely devoid of conducting additives, and more than 80mAh/g electrode with 10% carbon additive, as well as displaying an areal capacity as high as 3.4mAh/cm2 at C rate. Full cell validation was demonstrated over 1600 cycles by virtue of a commercial TEMPO molecule, which permitted an energy density of close to 40Wh/kgmaterials at C rate in a self-pH-buffered and inexpensive aqueous electrolyte.