Stable Bifunctional Perylene Imide Radicals for High‐Performance Organic–Lithium Redox‐Flow Batteries

Abstract

The search for high-performance organic redox-active materials for non-aqueous redox-flow batteries remains a key challenge. Organic radicals and aromatic imides are two promising classes of redox-active materials with complementary advantages, such as the specific capacity, operating voltage, and stability, etc. Herein, this work reports two stable bifunctional radicals synthesized by the C-C coupling of redox-active phenoxyl radicals and perylene diimides (PDIs, 1 ) or benzo[ghi]perylene triimides (BPTIs, 2 ). The incorporation of electron-deficient PDIs or BPTIs into phenoxyl radicals is desired, to not only increase the number of redox-active groups per molecule and, thus, improve their specific capacities, but also to increase the redox potential and the stability of the phenoxyl radicals and, thus, enhances their battery voltages and cycle lives. When serving as the redox-active species in the catholyte of a non-aqueous static redox-flow battery, both radicals 1 and 2 exhibited a cooperatively enhanced performance with an unprecedented initial discharge voltage up to 3.12 V versus Li /Li, which is the hitherto most presentable potential for imide- and radical-based energy storage materials in redox-flow batteries.

Effect of Aromatic Rings and Substituent on the Performance of Lithium Batteries with Rylene Imide Cathodes

“…The discharge curves of cells with molecule 4 showed two plateaus between 1.5 V and 4.2 V vs. Li/ Li + indicating two electron transfers (Figure 3a). Similar chargedischarge profiles were observed while using perylenebisimide [34,35] and naphthalenebisimde [36] derivatives in LIBs. The first plateau changed into a slope upon continuous cycling.…”

Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area

“…These include outstanding fluorescence quantum yields, [5] excellent stability against environmental influences and high electron affinity, allowing for fairly stable radical anionic states [6,7] as required for ambient stable n‐type semiconductors [8–10] . Their easy accessibility and the tailored properties arising by core functionalization promoted the application of PBI dyes in organic light emitting diodes (OLEDs), [11,12] organic thin‐film transistors (OTFTs), [10,13] and organic lithium batteries [14,15] . In particular, a wide range of applications of PBIs were recently explored in organic solar cells (OSCs) where they found use in interlayers, [16] as sensitizers, [17] or as non‐fullerene acceptors (NFAs) [18,19] .…”

“…[ 8 , 9 , 10 ] Their easy accessibility and the tailored properties arising by core functionalization promoted the application of PBI dyes in organic light emitting diodes (OLEDs),[ 11 , 12 ] organic thin‐film transistors (OTFTs),[ 10 , 13 ] and organic lithium batteries. [ 14 , 15 ] In particular, a wide range of applications of PBIs were recently explored in organic solar cells (OSCs) where they found use in interlayers, [16] as sensitizers, [17] or as non‐fullerene acceptors (NFAs). [ 18 , 19 ] Furthermore, PBIs are applied as fluorescence labels for bioimaging[ 20 , 21 ] and as fluorescence dyes for single‐molecule spectroscopy and microscopy.…”

Synthesis and self-assembly of a penta[60]fullerene bearing benzo[ghi]perylenetriimide units

“…The structure of compounds 5 and 6 were conrmed by their 1 H, 1 H-1 H COSY and 13 C NMR spectra (Fig. S1-S10 †) as well as by HR MALDI-TOF mass spectrometry (Fig.…”