US-12617804-B2 - Conjugation-fused bipolar redox-active molecule, preparation method, and application thereof

US12617804B2US 12617804 B2US12617804 B2US 12617804B2US-12617804-B2

Abstract

The present disclosure discloses a conjugation-fused bipolar redox-active molecule and its preparation method and application. The bipolar redox-active molecule includes a p-type redox active center and an n-type redox active center. The p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation.

Inventors

Yu Zhao
Gaole Dai
Yue Liu
Jing Ye
Huamei Li

Assignees

HANGZHOU NORMAL UNIVERSITY

Dates

Publication Date: 20260505
Application Date: 20220822
Priority Date: 20211101

Claims (2)

1 . A conjugation-fused bipolar redox-active molecule having a structural formula of
2 . A conjugation-fused bipolar redox-active molecule having a structural formula of

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims foreign priority of Chinese Patent Application No. 202111282577.2, filed on Nov. 1, 2021 in the China National Intellectual Property Administration, the disclosures of all of which are hereby incorporated by reference. TECHNICAL FIELD The present disclosure relates to the field of organic electrode material technologies, and in particular to a conjugation-fused bipolar redox-active molecule, a preparation method, and an application thereof. BACKGROUND Redox flow batteries (RFBs) are considered as one of the most promising electrochemical energy storage technologies for grid-scale energy storage, with significant advantages such as safety, long life, flexible configuration, and their power and energy density can be independently configured. RFBs currently under development have shown significant improvements in various aspects, but still have limitations such as low output voltage, cross-contamination between cathode and anode electrolytes, and low solubility of active materials. Unlike conventional redox-active organic molecules (ROMs), organic bipolar redox-active molecules (BRMs) can either lose electrons first and undergo an oxidation reaction or gain electrons first and undergo a reduction reaction, and the two redox reactions can proceed independently and are reversible. Therefore, the same redox-active molecules and electrolyte can be utilized in each half-cell component of formed symmetric redox flow batteries (SRFBs). This configuration can effectively reduce the chemical concentration gradient on both sides of the membrane of the flow batteries, which can mitigate the cross-contamination. Even if some of the active materials on both sides permeate during charging and discharging, the SRFBs can return to their initial state by self-discharge without irreversible effects. This is theoretically beneficial to improve the utilization efficiency of the BRMs and extend the lifetime of the RFBs, and these remarkable properties make the SRFBs promising for storage technology. Currently, the research on BRMs is mainly focused on screening and exploring new molecules with multiple redox reactions, as well as modifying existing BRMs to improve their solubility and stability. The modification strategies include forming bipolar eutectic mixtures, combining different types of redox-active molecules through covalent bonding or improving solubility or stability by introducing functionalized functional groups. These strategies extend the application of BRMs in RFBs and improve the solubility or structural stability of the materials. However, the current research on BRMs does not go beyond the traditional pairing of cathode and anode materials for organic flow batteries, and lacks the regulation of chemical/electrochemical properties of BRMs, such as the regulation of redox potential or redox reversibility. In particular, it does not change the lower output voltage of SRFBs, i.e., the voltage gap between the two redox reactions of BRMs is small, which cannot better exploit the advantages of all-organic-phase flow batteries. SUMMARY OF THE DISCLOSURE In order to solve the above technical problems, the present disclosure provides a conjugation-fused bipolar redox-active molecule and its preparation method and application. The present disclosure conjugately fuses two redox-active centers into one molecular unit, which may realize the regulation of redox potential of bipolar redox-active molecules and increase the output voltage of redox flow battery. Specific technical solution proposed are as followed. In a first aspect, the present disclosure provides a conjugation-fused bipolar redox-active molecule, comprising a p-type redox active center and an n-type redox active center; wherein the p-type redox active center and the n-type redox active center are fused in a molecular unit by conjugation. The bipolar redox-active molecules can be used in symmetric redox flow batteries (SRFBs) as active materials in both cathode and anode electrolytes of the batteries, which can effectively reduce the chemical concentration gradient on both sides of the membrane of the flow batteries, mitigating the cross-contamination. Even if some of the active materials on both sides permeate during charging and discharging, the SRFBs can return to their initial state by self-discharge without irreversible effects. This is theoretically beneficial to improve the utilization efficiency of the BRMs and extend the lifetime of the RFBs. Moreover, the present disclosure fuses different types (p-type and n-type) of redox-active centers into one molecular unit by conjugation, and achieves the regulation of redox potential of BRMs by the intra-molecular charge transfer effect. The specific mechanism is shown in FIG. 1: after conjugate fusion of two redox-active centers, the electron cloud around the p-type active center (e.g., quaternary nitrogen) is attracted by the n-type active center (e