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CN-122025717-A - All-vanadium redox flow battery composite electrolyte containing multiple electron additives and preparation method thereof

CN122025717ACN 122025717 ACN122025717 ACN 122025717ACN-122025717-A

Abstract

The invention discloses a composite electrolyte of an all-vanadium redox flow battery containing a multi-electron additive and a preparation method thereof, and belongs to the technical field of redox flow batteries, wherein the composite electrolyte comprises vanadium main active substances (1.6-2.0 mol/l), positive multi-electron additives, negative multi-electron additives, a nitrogen-containing organic phosphonic acid compound (0.05-0.15 mol/l) and a preparation method thereof, the vanadium main active substances comprise ferricyanide (0.2-0.5 mol/l) containing [ Fe (CN) 6 ] 4‑ ], the temperature stabilizer is added into the positive electrolyte, the ferricyanide is controlled to be less than or equal to 0.1ppm in a dissolving process, the energy density and the temperature stability of the all-vanadium redox flow battery are improved through the synergistic effect of the multi-electron additives and the temperature stabilizer, and the technical problems of low energy density and low temperature adaptability of the traditional all-vanadium redox flow battery are solved.

Inventors

  • GAO MENGMENG
  • LUO SAINAN
  • WANG SHUO
  • GUI BIN
  • CHEN JINKUN
  • LIANG XIAOLONG

Assignees

  • 宿迁盛瑞新材料有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (8)

  1. 1. The all-vanadium redox flow battery composite electrolyte containing the multi-electron additive is characterized by comprising an anode electrolyte and a cathode electrolyte, wherein the anode electrolyte comprises 1.6-2.0mol/l of vanadium main active material, 0.2-0.5mol/l of ferricyanide and 0.05-0.15mol/l of nitrogen-containing organic phosphonic acid compound, and the cathode electrolyte comprises 1.6-2.0mol/l of vanadium main active material, 0.1-0.3mol/l of soluble titanium salt and 0.05-0.15mol/l of nitrogen-containing organic phosphonic acid compound.
  2. 2. The multi-electron additive-containing all-vanadium redox flow battery composite electrolyte of claim 1, wherein the ferricyanide is [ Fe (CN) 6 ] 4- -containing ferricyanide.
  3. 3. The multi-electron additive-containing all-vanadium redox flow battery composite electrolyte of claim 2, wherein the ferricyanide is K 4 [Fe(CN) 6 or Na 4 [Fe(CN) 6 .
  4. 4. The multi-electron additive-containing all-vanadium redox flow battery composite electrolyte according to claim 1, wherein the soluble titanium salt is (NH 4 ) 2 [TiO(SO 4 ) 2 ) or TiOSO 4 .
  5. 5. The multi-electron additive-containing all-vanadium redox flow battery composite electrolyte according to claim 1, wherein the nitrogen-containing organic phosphonic acid compound is one of aminotrimethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid and diethylenetriamine pentamethylene phosphonic acid.
  6. 6. The multi-electron additive-containing all-vanadium redox flow battery composite electrolyte according to claim 1 is characterized in that vanadium main active materials in the positive electrode electrolyte comprise VO 2+ 、VO 2 + and vanadium main active materials in the negative electrode electrolyte comprise V 2+ 、V 3+ .
  7. 7. The method for preparing the composite electrolyte of the all-vanadium redox flow battery containing the multi-electron additive according to any one of claims 1 to 6, which is characterized by comprising the steps of injecting a soluble titanium salt solution into a negative electrolyte containing vanadium main active materials under an inert atmosphere according to the concentration of claim 1, injecting ferricyanide solution into a positive electrolyte containing vanadium main active materials, respectively adding nitrogen-containing organic phosphonic acid compounds, and performing ultrasonic treatment for 30 to 60 minutes.
  8. 8. The method for preparing the composite electrolyte of the all-vanadium redox flow battery containing the multi-electron additive, which is disclosed in claim 6, is characterized in that the dissolution process of the soluble titanium salt is controlled to be less than or equal to 0.1ppm of dissolved oxygen, and the mixing temperature is 35-45 ℃.

Description

All-vanadium redox flow battery composite electrolyte containing multiple electron additives and preparation method thereof Technical Field The invention relates to the technical field of electrochemical energy storage, in particular to a vanadium redox flow battery composite electrolyte containing multiple electron additives and a preparation method thereof. Background As a large-scale energy storage technology, the all-vanadium redox flow battery has the advantages of independent energy and power adjustment, long cycle life, high response speed and the like, and has wide application prospects in the fields of renewable energy grid connection, intelligent power grids and long-term energy storage. However, the conventional all-vanadium redox flow battery has the problems of low energy density, poor temperature adaptability, performance attenuation under high current density and the like, and is limited to large-scale commercial application. The energy density of the traditional all-vanadium redox flow battery is mainly limited by the solubility, concentration and single-electron reaction mechanism of vanadium ions in electrolyte. The vanadium ion concentration of the current commercial all-vanadium redox flow battery is generally 1.6-2.0mol/L, the energy density of the system is about 15-30Wh/L, and the energy density is lower. CN118299630B discloses a high-capacity positive electrode electrolyte of an all-vanadium redox flow battery, and the battery capacity is improved by adding a targeted redox solid energy storage substance containing ammonia-rich iron/copper ferrocyanide, but the method increases the complexity of a system, a complex structure which can not only contain the solid energy storage substance but also ensure smooth circulation of the electrolyte is required to be designed, and the fluidity of the solid material is possibly reduced, and the capacity attenuation is irreversible. Temperature adaptability is another key challenge faced by all-vanadium redox flow batteries. Under the high temperature environment (> 40 ℃), VO 2+ in the positive electrode electrolyte is easy to generate precipitation through thermal hydrolysis reaction, flow channels and electrodes are blocked, so that the battery capacity is reduced, and under the low temperature environment (< 10 ℃), V 3+ in the negative electrode electrolyte is easy to crystallize and separate out, a system is possibly blocked, the viscosity of the electrolyte is increased, and the ion transmission efficiency is reduced. CN105762395B proposes an all-vanadium flow battery positive electrode electrolyte containing a phosphate and tungstate composite additive, which can effectively inhibit the capacity fading problem under the high temperature condition, but has limited improvement on low temperature stability. In addition, the traditional all-vanadium redox flow battery has obvious kinetic retardation problem under high current density, serious polarization phenomenon, rapid change of battery voltage and reduced available capacity, and the power performance and energy efficiency of the battery are seriously affected. The improvement scheme in the prior art is mostly optimized for a single problem, such as only improving energy density or only improving temperature adaptability, and lacks a comprehensive solution capable of simultaneously solving multiple problems of energy density bottleneck, poor temperature adaptability, insufficient dynamic performance and the like. In addition, most of the existing additives have single functions, and the synergistic effect of multiple electron transfer reactions and temperature stabilization is difficult to realize, so that the temperature adaptability of the battery is often sacrificed while the energy density is improved, or the energy density of the battery is reduced while the temperature adaptability is improved. Therefore, there is a need to develop an all-vanadium redox flow battery composite electrolyte capable of simultaneously improving energy density, improving temperature adaptability and enhancing electrochemical kinetics. Disclosure of Invention The invention provides an all-vanadium redox flow battery composite electrolyte capable of simultaneously solving the problems in the background art, aiming at the problems of energy density bottleneck, temperature sensitivity, kinetic retardation under high current density and the limitations of the existing improvement scheme of the conventional all-vanadium redox flow battery. In order to achieve the above purpose, the present invention provides the following technical solutions: the invention provides a composite electrolyte of an all-vanadium redox flow battery containing a multi-electron additive, which comprises the following components: Vanadium main active materials, namely V 2+/ V3+ (cathode) and VO 2+/ VO2+ (anode), with the concentration of 1.6-2.0mol/l; A positive electrode multi-electron additive, which is ferricyanide (positive electrode