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

Abstract

By virtue of their high energy efficiency, facile scalability, intrinsic safety, not to mention low cost and environmental compatibility, aqueous batteries are being increasingly 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, 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 + , Mg 2+ , and Cl − . Reaching up to 105 mAh g −1 , 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 60 mAh g −1 electrode while entirely devoid of conducting additives, and more than 80 mAh g −1 electrode with 10% carbon additive, as well as displaying an areal capacity as high as 3.4 mAh cm −2 at C rate. Full cell validation was demonstrated over 1600 cycles by virtue of a commercial 2,2,6,6-tétraméthylpipéridin-1-yl)oxyl (TEMPO) molecule, which permitted an energy density of close to 40 Wh kg −1 materials at C rate in a self-pH-buffered and inexpensive aqueous electrolyte.

Progress of Organic Electrodes in Aqueous Electrolyte for Energy Storage and Conversion

“…recently proposed a new intermixed charge‐storage mechanism by merging p‐ and n‐type organic moieties together into a short oligomer, which mitigates volume variations upon cycling of the material . Such an advanced p/n‐type organic scaffold simultaneously stored ClO 4 − and Na + with an improved capacity (up to 105 mAh g −1 per mass of material) and high cyclability (over 6 500 cycles with 82.8 % retention at 2.4 A g −1 ) …”

“…For example, organics containing carbonyl groups are employed to build next‐generation batteries with organic electrolytes, such as Li (or Na) metal–organic batteries . Recently, organics have been employed in aqueous electrolyte for the fabrication of aqueous Li‐ion (also, Na‐ion or K‐ion) batteries, showing high cyclability and high power . However, it was found that the discharge products of monovalent metal cations (for example, C‐O‐Li + ) were easily oxidized by the dissolved O 2 in the aqueous electrolyte, leading to the problem of self‐discharge .…”

Progress of Organic Electrodes in Aqueous Electrolyte for Energy Storage and Conversion

“…For example, organics containing carbonyl groups are employed to build next‐generation batteries with organic electrolytes, such as Li (or Na) metal–organic batteries . Recently, organics have been employed in aqueous electrolyte for the fabrication of aqueous Li‐ion (also, Na‐ion or K‐ion) batteries, showing high cyclability and high power . However, it was found that the discharge products of monovalent metal cations (for example, C‐O‐Li + ) were easily oxidized by the dissolved O 2 in the aqueous electrolyte, leading to the problem of self‐discharge .…”

A Quinone Anode for Lithium‐Ion Batteries in Mild Aqueous Electrolytes

“…With electricity increasingly generated from renewable resources such as solar and wind power, energy storage devices have become more and more indispensable in balancing the electricity supply and demand . Aqueous lithium‐ion batteries (ALIBs), featuring safety and long cycle life, could become a viable option serving as energy storage devices .…”