Made to Measure Squaramide COF Cathode for Zinc Dual‐Ion Battery with Enriched Storage via Redox Electrolyte

Abstract

Aqueous rechargeable batteries are promising grid‐scale energy storage devices because of their affordability, operational safety, and environmental benignity. Among these, Zn‐ion batteries (ZIBs) have unfolded new horizons. Designing superior cathodes for ZIBs is crucial. Covalent organic frameworks (COFs) can be made redox active with a high storage surface. Here, for the first time, a chelating COF with redox‐active ZnI2 in a ZnSO4(aq) electrolyte is combined. Including iodide harvests an approximately threefold enhancement in capacity from 208 to 690 mAh g−1 at 1.5 A g−1, the highest among all the COF‐derived ZIBs. Remarkably, a charge–discharge curve at 1.3 V exhibits very limited dropout voltage and super‐flat platform, with a remarkable capacity of 600 mAh g−1 at 5 A g−1 stable up to 6000 cycles, confirming that the polyiodide generation and storage are sustainable. The COF's dual‐ion storage (Zn2+ and polyidode) delivers a ZIB with the highest energy density. Spectro‐electrochemical measurements coupled with X‐ray photoelectron spectroscopy unambiguously unveil the existence of multiple polyiodide species, with I3− and IO3− ions as the prominent species. The latter gets reduced at the COF electrode under an applied potential, leaving I3− as the major species stored on the COF. The prospect of COF‐polyiodide(aq) is a windfall for metal‐ion batteries.

Tailoring COFs: Transforming Nonconducting 2D Layered COF into a Conducting Quasi-3D Architecture via Interlayer Knitting with Polypyrrole

“…Such values are typical of chemically pure intrinsic semiconductors having high band gaps at room temperature. ,, In contrast, COF20-Ppy displayed a much higher electronic conductivity of 1.88 × 10 –2 S m –1 (Figure B). This improved conductivity arises from the extended conjugation offered to the COF layers by the covalently cross-linked polypyrrole chains.…”

Design enhancement in hydroxide ion conductivity of viologen–bakelite organic frameworks for a flexible rechargeable zinc–air battery

“…Rechargeable zinc–air batteries (RZABs) represent a promising candidate for the development of flexible energy storage solutions. 1–14 This potential is rooted in their uncomplicated architecture, capacity to be modeled into diverse shapes, environment-friendly attributes, cost-effectiveness, and high energy and power density. 15–17 Traditionally, a battery having an alkaline electrolyte with a zinc anode is desirable due to the inherent electrochemical reversibility and fast kinetics ( e.g.…”

Suppressing the Shuttle Effect of Aqueous Zinc–Iodine Batteries: Progress and Prospects

“…Zinc metal is an ideal anode for aqueous batteries due to its high theoretical capacity (820 mAh g −1 , 5854 mAh cm −3 ), low redox potential (−0.76 V vs. SHE), good compatibility and stability in aqueous electrolytes, low price, and wide range of sources [14][15][16]. In the past decade or so of research, cathode materials for aqueous zinc ion batteries have emerged, mainly including vanadium-based compounds [17], manganese-based compounds [18], PBAs [19], organic compounds [20], transition metal group sulfides [21], and other materials. However, the comprehensive performance index of these cathode materials is not high, their capacity is generally lower than 300 mAh g −1 , and the discharge voltage is generally lower than 0.8 V vs. SHE [22,23].…”