利用尿素类似物提升4-OH-TEMPO正极液容量及其在液流电池中的应用

冯啟冰; 李喆珺

doi:10.19799/j.cnki.2095-4239.2026.0315

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利用尿素类似物提升4-OH-TEMPO正极液容量及其在液流电池中的应用

储能材料与器件 | 更新时间：2026-08-26

- 利用尿素类似物提升4-OH-TEMPO正极液容量及其在液流电池中的应用
- Urea analogues as functional additives for high-capacity 4-OH-TEMPO posolyte for redox flow batteries
- 储能科学与技术 2026年15卷第8期页码：3009-3017
- 作者机构：
  
  1.武汉大学物理科学与技术学院，湖北武汉 430072
  2.武汉大学苏州研究院，江苏苏州 215123
- 作者简介：
  
  冯啟冰（2002—），男，硕士研究生，研究方向为水系有机液流电池，E-mail：fqbing0513@163.com；
  李喆珺，教授，研究方向为电化学储能，E-mail：zhejunli@whu.edu.cn。
- 基金信息：
  
  国家自然科学基金(22378319);江苏省自然科学基金(BK20230269)
- DOI：10.19799/j.cnki.2095-4239.2026.0315
  中图分类号： TM 912
- 收稿：2026-04-14，
  
  修回：2026-06-18，
  
  网络首发：2026-08-26，
  
  纸质出版：2026-08-28
- 稿件说明：
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冯啟冰, 李喆珺. 利用尿素类似物提升4-OH-TEMPO正极液容量及其在液流电池中的应用[J]. 储能科学与技术, 2026, 15(8): 3009-3017.

FENG Qibing, LI Zhejun. Urea analogues as functional additives for high-capacity 4-OH-TEMPO posolyte for redox flow batteries[J]. Energy Storage Science and Technology, 2026, 15(8): 3009-3017.
冯啟冰, 李喆珺. 利用尿素类似物提升4-OH-TEMPO正极液容量及其在液流电池中的应用[J]. 储能科学与技术, 2026, 15(8): 3009-3017. DOI： 10.19799/j.cnki.2095-4239.2026.0315.

FENG Qibing, LI Zhejun. Urea analogues as functional additives for high-capacity 4-OH-TEMPO posolyte for redox flow batteries[J]. Energy Storage Science and Technology, 2026, 15(8): 3009-3017. DOI： 10.19799/j.cnki.2095-4239.2026.0315.

摘要

4-羟基-2

6-四甲基哌啶-1-氧自由基（4-OH-TEMPO，4-HT）作为水系有机液流电池阴极电解液材料表现出良好的氧化还原可逆性，但其在中性水溶液中的本征溶解度仅约2.1 mol/L，严重限制了电池的能量密度。针对这一问题，选用尿素类似物甲基脲（MU）和乙基脲（EU）作为氢键供体/受体添加剂，通过分子间相互作用提升4-HT在水相中的表观溶解度，在不改变其分子结构的前提下实现物理增溶。通过紫外-可见分光光度法（UV-vis）系统测定了不同浓度添加剂条件下4-HT的饱和溶解度，利用核磁共振氢谱（

H NMR）分析了添加剂与4-HT之间的氢键相互作用机制，并结合循环伏安测试、旋转圆盘电极测试、电化学阻抗谱及全电池充放电测试，评估了增溶后电解液的理化性质、电化学可逆性及在实际液流电池中的循环稳定性。结果表明，EU性能更优，可将4-HT的饱和溶解度提升至4.9 mol/L。核磁共振结果显示，添加剂与4-HT之间通过氢键形成深共晶溶液，其中EU与4-HT的氢键作用更强，与其更高的增溶效果一致。增溶后电解液的扩散系数略有下降，但电化学可逆性保持良好，氧化还原峰电位差维持在81 mV。组装的全电池在20 mA/cm

电流密度下循环100圈后，添加MU和EU的体系平均库仑效率均达96.5%，高于空白组的96%，容量保持率分别提升至76%和86%，远高于空白组的17%。本研究提出并验证了一种基于尿素类似物的物理增溶策略，在不破坏4-HT电化学性能的前提下显著提升其溶解度与能量密度，为开发高能量密度水系有机液流电池提供了一条简便有效的技术路径。

Abstract

4-Hydroxy-2

6-tetramethylpiperidine-1-oxyl (4-OH-TEMPO

4-HT) exhibits favorable redox reversibility as a catholyte material for aqueous organic flow batteries. However

its intrinsic solubility in neutral aqueous solutions is only about 2.1 mol/L

which severely limits the energy density of the battery. To address this issue

this study proposes the use of urea analogues

namely methylurea (MU) and ethylurea (EU)

as hydrogen bond donor/acceptor additives to enhance the apparent solubility of 4-HT in the aqueous phase through intermolecular interactions

achieving physical solubilization without altering its molecular structure. The saturated solubility of 4-HT under different additive concentrations was systematically determined using ultraviolet-visible (UV-vis) spectropho

tometry. The hydrogen bonding interaction mechanism between the additives and 4-HT was analyzed by proton nuclear magnetic resonance (

H NMR) spectroscopy. Combined with cyclic voltammetry

rotating disk electrode

electrochemical impedance spectroscopy

and single-cell charge-discharge tests

the physicochemical properties

electrochemical reversibility

and cycling stability of the solubilized electrolytes in actual flow batteries were comprehensively evaluated. The results showed that EU exhibited superior performance and could increase the solubility of 4-HT to 4.9 mol/L. NMR results indicated the formation of deep eutectic solution through hydrogen bonding between the additives and 4-HT

with EU showing stronger hydrogen bonding interactions than MU

which is consistent with its better solubilization effect. After solubilization

the diffusion coefficient of the electrolyte decreased slightly

but the electrochemical reversibility remained good

with the redox peak potential difference maintained at 81 mV. In full-cell tests at a current density of 20 mA/cm² over 100 cycles

the average Coulombic efficiencies of the systems with MU and EU both reached 96.5%

higher than the 96% of the blank group

while the capacity retention rates increased to 76% and 86%

respectively

significantly higher than the 17% of the blank group. This study proposes and validates a physical solubilization strategy based on urea analogues

which significantly enhances the solubility and energy density of 4-HT without compromising its electrochemical performance

providing a simple and effective technical pathway for the development of high-energy-density aqueous organic flow batteries.

关键词

Keywords

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