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CN-122025720-A - Zinc-bromine flow battery electrolyte, zinc-bromine flow battery and application

CN122025720ACN 122025720 ACN122025720 ACN 122025720ACN-122025720-A

Abstract

The invention relates to the technical field of zinc-bromine flow battery preparation, in particular to zinc-bromine flow battery electrolyte, a zinc-bromine flow battery and application thereof, and the zinc-bromine flow battery electrolyte comprises water, zinc bromide, supporting electrolyte and 1-propyl-3-methylimidazole bromide, wherein the concentration of the 1-propyl-3-methylimidazole bromide in the zinc-bromine flow battery electrolyte is 0.2-2mol/L. In the aspect of the cathode, the 1-propyl-3-methylimidazole bromide can regulate and control the solvation structure of Zn 2+ , effectively improve the uniformity of zinc deposition and inhibit the formation of zinc dendrites. Meanwhile, in the aspect of the anode, a 1-propyl-3-methylimidazole bromine salt complex is formed between imidazole cations and Br 2 molecules, free bromine is immobilized through pi-pi bond interaction and hydrogen bond interaction, so that the concentration of Br 3 ‑ in the electrolyte is improved, and the problems of dendrite growth of a zinc anode of a zinc-bromine flow battery and high activity and volatility of a positive bromine simple substance are solved.

Inventors

  • LI JUNWAN
  • WANG YAMENG
  • WANG DEJUN
  • WANG HAORAN
  • Tan Guangdao
  • LI TIANLUN
  • ZHAO WEILU
  • LI HONG
  • YUAN XIAO

Assignees

  • 西安热工研究院有限公司
  • 华能赫章风力发电有限公司

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The zinc-bromine flow battery electrolyte is characterized by comprising water, zinc bromide, supporting electrolyte and 1-propyl-3-methylimidazole bromide, wherein the concentration of the 1-propyl-3-methylimidazole bromide in the zinc-bromine flow battery electrolyte is 0.2-2mol/L.
  2. 2. The zinc-bromine flow battery electrolyte of claim 1 wherein the concentration of zinc bromide in the zinc-bromine flow battery electrolyte is 2-2.5mol/L.
  3. 3. The zinc-bromine flow battery electrolyte of claim 1 wherein the supporting electrolyte comprises one or both of KCl, naCl, and NH 4 Cl.
  4. 4. The zinc-bromine flow battery electrolyte of claim 1 wherein the concentration of supporting electrolyte in the zinc-bromine flow battery electrolyte is 1-2mol/L.
  5. 5. The zinc-bromine flow battery electrolyte according to claim 1, wherein the preparation method of the 1-propyl-3-methylimidazole bromide is as follows: Uniformly mixing 1-methylimidazole and 1-bromopropane to obtain a mixed solution; Adding ethyl acetate into the mixed solution for reaction, standing, and taking out the lower layer liquid to obtain the 1-propyl-3-methylimidazole bromide.
  6. 6. The zinc-bromine flow battery electrolyte according to claim 5, wherein the volume ratio of the 1-methylimidazole to the 1-bromopropane is (1-2): (1-2), and the volume ratio of the mixed solution to the ethyl acetate is (2-4): 1.
  7. 7. A zinc-bromine flow battery, comprising a positive electrode, a negative electrode, a diaphragm and the zinc-bromine flow battery electrolyte of any one of claims 1-6; The positive electrode, the negative electrode and the diaphragm are immersed in the electrolyte of the zinc-bromine flow battery, and the positive electrode and the negative electrode are physically isolated through the diaphragm.
  8. 8. The zinc-bromine flow battery of claim 7, wherein the separator is a microporous membrane or a Nafion membrane.
  9. 9. The zinc-bromine flow battery of claim 7 wherein the positive electrode and the negative electrode are each based on carbon felt.
  10. 10. Use of the zinc-bromine flow battery electrolyte of any one of claims 1-6 in the field of energy storage.

Description

Zinc-bromine flow battery electrolyte, zinc-bromine flow battery and application Technical Field The invention relates to the technical field of zinc-bromine flow battery preparation, in particular to zinc-bromine flow battery electrolyte, a zinc-bromine flow battery and application. Background Along with the transformation of global energy structures and the rapid development of renewable energy sources (such as wind energy and solar energy), a large-scale energy storage technology becomes a key link for solving the fluctuation of energy supply and demand and improving the stability of a power grid. Although the traditional lithium ion battery is dominant in the fields of portable electronic equipment and electric automobiles, the problems of resource scarcity, high cost and safety limit the application of the traditional lithium ion battery in a large-scale energy storage scene. In this context, flow batteries are becoming a research hotspot in the field of large-scale energy storage due to their unique structural design (decoupling of energy storage and power output) and long life characteristics. Among them, zinc-bromine flow batteries (Zinc-Bromine Flow Battery, ZBFB) are considered as one of the most commercialized flow batteries by virtue of their advantages of high theoretical energy density, low raw material cost (abundant reserves of Zinc and bromine), environmental friendliness, etc. The core principle of the zinc-bromine flow battery is based on oxidation-reduction reaction of a zinc cathode and bromination/debromination reaction of a bromine anode. During charging, zinc ions are deposited as metallic zinc at the negative electrode, bromine ions are oxidized into bromine simple substance at the positive electrode, and during discharging, zinc is dissolved as zinc ions, and bromine simple substance is reduced into bromine ions. The reversible electrochemical reaction gives the zinc-bromine flow battery the potential of high energy efficiency, long cycle life and low cost operation and maintenance, and is especially suitable for large-scale energy storage scenes such as power grid peak shaving, renewable energy grid connection and the like. However, despite the excellent performance exhibited by zinc-bromine flow batteries in laboratory studies, the commercialization process thereof still faces two major challenges, namely dendrite growth problems of zinc cathodes and high activity and volatility problems of the positive bromine element. Zinc dendrite formation results from uneven deposition of zinc ions on the electrode surface during charging, resulting in the growth of dendritic or mossy structures. Zinc dendrites can not only puncture the separator to cause shorting between the positive and negative electrodes, but also form "dead zinc" (non-reacted zinc deposits) during dissolution, resulting in loss of active material and capacity fade. The high activity and volatility of the bromine simple substance at the positive electrode are mainly caused by the strong migration capability of polybrominated ions (such as Br 3- and Br 5-) generated in the discharging process, and the polybrominated ions can diffuse to the negative electrode side (namely 'bromine shuttling') through the diaphragm, so that irreversible side reaction occurs with the zinc negative electrode, the self-discharging and coulomb efficiency are reduced, and meanwhile, the volatility and strong corrosiveness of the bromine simple substance bring extremely high requirements on the sealing design, the environmental safety and the material compatibility of the battery. These problems not only directly lead to the shortening of the cycle life and the reduction of the coulombic efficiency of the battery, but also can cause potential safety hazards (such as membrane puncture and electrolyte leakage), and become a key technical bottleneck for limiting the large-scale application of the battery. In the prior art, in order to address the above challenges, a "divide-and-conquer" method is generally adopted, namely, functional additives are respectively added into the electrolyte to inhibit zinc dendrite growth or fix bromine simple substance in a targeted manner, so that the battery performance is improved. To inhibit dendrite growth, the prior art modifies the zinc deposition interface by adding metal ions (e.g., pb 2+ and In 3+) or surfactants (e.g., polyethylene glycol and sodium lauryl sulfate). These additives promote uniform deposition by adsorbing on the zinc surface, altering the deposition kinetics of zinc ions, thus retarding dendrite formation. In addition, part of researches further improve the uniformity of zinc deposition by optimizing the composition of the electrolyte (such as adjusting the concentration of zinc salt and adding an organic solvent) or designing a three-dimensional porous electrode structure. Aiming at the problems of high activity and volatility of the positive bromine simple substance, the prior art mainly ad