基于双电荷中心溴络合剂的高容量锌溴液流电池的研究

doi:10.19799/j.cnki.2095-4239.2025.0646

摘要/Abstract

摘要：

针对锌溴液流电池中聚溴阴离子(Br_2n+1^-)在高浓度下的跨膜穿梭效应导致电池容量与循环稳定性下降的关键问题，本工作开展了双电荷中心季铵盐溴络合剂对锌溴液流电池聚溴阴离子穿梭效应的抑制机制与电化学性能提升的研究。通过霍夫曼烷基化反应设计合成具有高亲水性的双电荷中心季铵盐溴络合剂，N₁, N₅-二甲基-N₁, N₁, N₅, N₅-四(2-羟乙基)-1, 5-二溴化戊二铵(N₂MDA)，采用密度泛函理论计算以及核磁共振氢谱分析，阐明其与聚溴阴离子的静电力组装结构和过程。研究表明：“双电荷中心组装”策略使得N₂MDA与聚溴阴离子之间的静电作用增强，较强的静电相互作用使得N₂MDA与聚溴阴离子在高浓度条件下形成大体积离子聚集体，该离子聚集体有效抑制了聚溴阴离子的跨膜穿梭。将双电荷中心溴络合剂N₂MDA应用于锌溴液流电池测试中，仅需添加0.10 mol/L N₂MDA即可实现90%的库伦效率，所制备的液流电池容量可以达到57.0 Ah/L，且表现出优异的循环稳定性。该研究为发展高效溴管理策略与高性能锌溴液流电池提供了新材料设计与机理支持。

关键词: 均相溴络合剂, 双电荷中心季铵盐, 高容量, 锌溴液流电池

Abstract:

To address the critical issues of capacity decay and cycling instability caused by the crossover of polybromide anions (Br_2n+1^-) under high concentration conditions in zinc-bromine flow batteries (ZBFBs), this work investigates the suppression mechanism of shuttle effect and the enhancement of electrochemical performance using a dual-charge-center quaternary ammonium bromine complexing agent. A highly hydrophilic dual-positive charges quaternary ammonium bromine complexing agent, N₁,N₅-dimethyl-N₁,N₁,N₅,N₅-tetrakis(2-hydroxyethyl)-1,5-pentanediammonium dibromide (N₂MDA), was developed by Hoffmann alkylation reaction. The electrostatic assembly structure and process between N₂MDA and polybromide anions were elucidated using density functional theory calculations and ¹H NMR spectroscopy analysis. The results show that the "dual-positive charges assembly" strategy significantly enhances the binding capability of N₂MDA to polybromide anions. The strong electrostatic interaction facilitates the formation of large-volume ionic aggregates under high concentration conditions, thereby effectively inhibiting the transmembrane shuttle of polybromide anions. By applying the dual-positive charges complexing agent N₂MDA to ZBFBs, only 0.10 mol/L of N₂MDA additive can achieve a Coulombic efficiency exceeding 90%, and the capacity of the prepared flow batteries can reach 57.0 Ah/L, with excellent cycling stability (capacity retention of 100.0% over 300 cycles). This research provide a novel material design and mechanistic support for developing efficient bromine management strategy and high-performance ZBFBs.

Key words: homogeneous bromine complexing agent, dual-positive charges quaternary ammonium salt, high capacity, zinc-bromine flow battery

中图分类号:

陈俊卫, 黄国治, 彭思然, 文贤馗, 范强, 李朝杰, 胡全, 李伟平, 郝国豪, 李文津, 王超. 基于双电荷中心溴络合剂的高容量锌溴液流电池的研究[J]. 储能科学与技术, doi: 10.19799/j.cnki.2095-4239.2025.0646.

Junwei CHEN, Guozhi HUANG, Siran PENG, Xiankui WEN, Qiang FAN, Chaojie LI, Quan HU, Weiping LI, Guohao HAO, Wenjin LI, Chao WANG. A Dual-Positive Charges Strategy to Manage Bromine for High-Capacity Zinc-Bromine Flow Battery[J]. Energy Storage Science and Technology, doi: 10.19799/j.cnki.2095-4239.2025.0646.

图/表 13

图1

图2

表1

络合剂N2MDA与聚溴阴离子的相互作用能量分解"

Unit: kcal/mol	N₂MDABr₃	N₂MDABr₅	N₂MDA(Br₃)₂	N₂MDA(Br₅)₂
$∆ E e l s$	-125.10	-142.22	-201.97	-206.90
$∆ E x r e p$	27.37	54.54	77.71	100.67
$∆ E o r b$	-14.56	-20.68	-31.84	-30.71
$∆ E d i s p$	-19.93	38.84	-48.90	-68.69
$∆ E t a t t$	-159.59	-201.74	-282.71	-306.30

表1

图3

图4(a)

图5(a)

图6

图7

图8

图9

图S1

图S2

图S3

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