CN-122000399-A - Positive electrode electrolyte and titanium cerium flow battery

Abstract

The invention belongs to the technical field of flow batteries, and relates to an anode electrolyte and a titanium cerium flow battery, wherein the anode electrolyte is formed by mixing an initial electrolyte and a hydrogen peroxide solution, and the initial electrolyte is an acidic aqueous solution containing a supporting electrolyte and cerium ions. According to the invention, the hydrogen peroxide solution is mixed into the initial electrolyte to serve as a reducing additive, so that the efficiency and the cycle life of the titanium-cerium flow battery are effectively improved.

Inventors

• ZHANG HUI
• LIU RUOCHEN
• XIE YANGYANG
• Fu Shangwan
• WU YATING
• QI TAO

Assignees

• 中国科学院赣江创新研究院

Dates

Publication Date

20260508

Application Date

20260204

Claims (6)

1. 1. The positive electrode electrolyte is characterized by being prepared by mixing an initial electrolyte and a hydrogen peroxide solution, wherein the initial electrolyte is an acidic aqueous solution containing a supporting electrolyte and cerium ions.
2. 2. The positive electrode electrolyte according to claim 1, wherein the concentration of cerium ions in the positive electrode electrolyte is 0.1 to 2mol/L and the concentration of hydrogen ions is 0.5 to 8mol/L.
3. 3. The positive electrode electrolyte according to claim 1 or 2, wherein the amount of H 2 O 2 in the hydrogen peroxide solution is 0.5-1.5 times m 0 , preferably 1.0-1.2 times m 0 ; Wherein m 0 is calculated by the following formula (1): In the above formula, M 0 is the theoretical dosage of H 2 O 2 , the unit is g, C v is the concentration of cerium ions in the initial electrolyte, the unit is mol/L, V is the volume of the initial electrolyte, the unit is L, Q 'is the charging capacity of the titanium cerium flow battery assembled by using the initial electrolyte with the volume of V' after the first charge and discharge cycle, the unit is C, k is the ratio of V to V ', namely k=V/V', and M is the relative molecular mass of H 2 O 2 , and the value is 34.
4. 4. The positive electrode electrolyte according to any one of claims 1 to 3, wherein the supporting electrolyte comprises at least one of methanesulfonic acid, sulfuric acid, or sulfamic acid.
5. 5. The positive electrode electrolyte according to claim 4, wherein the supporting electrolyte is a combination of methanesulfonic acid and sulfuric acid, and the molar concentration ratio of methanesulfonic acid to sulfuric acid is (0.1 to 10): 1, preferably (1 to 5): 1.
6. 6. The titanium cerium flow battery is characterized in that an electrolyte system of the titanium cerium flow battery is composed of a negative electrode electrolyte and the positive electrode electrolyte according to any one of claims 1-5, wherein the negative electrode electrolyte is an acidic aqueous solution containing a supporting electrolyte and titanium ions.

Description

Positive electrode electrolyte and titanium cerium flow battery Technical Field The invention belongs to the technical field of flow batteries, and relates to an anode electrolyte, in particular to an anode electrolyte and a titanium cerium flow battery. Background The titanium cerium flow battery is a novel flow battery, and cerium ions in positive electrolyte and titanium ions in negative electrolyte are used as active substances. The method has the advantages of high theoretical energy density, high battery voltage, low cost, safety, environmental protection and the like, and has wide application prospect in the field of large-scale energy storage. The titanium cerium flow battery takes a Ce 4+/Ce3+ anode and a Ti 3+/Ti4+ cathode as redox pairs, has the advantages of high potential window, environmental protection and low cost in theory, and has been studied more and more in the field of distributed energy storage in recent years. Around the optimization of the positive electrode electrolyte, researches mainly focus on the cooperative regulation and control of cerium ion concentration, acid medium type and additives. In the early stage, a sulfuric acid system of 0.1-0.5 mol/L Ce3+ is adopted, the hydrolysis of Ce 4+ is inhibited by increasing the acidity to more than 4mol/L, but the corrosion to sealing materials is aggravated by a concentrated acid environment, in addition, organic acids such as methanesulfonic acid, sulfamic acid and the like are introduced, the solubility of cerium is improved by utilizing the weak coordination effect of the organic acids, the hydrogen evolution side reaction is reduced, and the energy efficiency of 110 cycles of 50mA/cm 2 is maintained to be more than 80 percent. In order to further improve the reaction kinetics, researches are carried out on adding complexing agents such as sulfosalicylic acid, EDTA and the like, reducing the charge transfer impedance of Ce 4+/Ce3+ by adjusting the coordination environment, and still maintaining the voltage efficiency of more than 90% at 100mA/cm 2. However, the conventional positive electrode electrolyte still faces various bottlenecks, namely, ce 4+ is easy to hydrolyze under low acidity to generate CeO 2·xH2 O colloid which gradually blocks an electrode pore canal and a pipeline along with electrolyte circulation to cause rapid rise of polarization internal resistance and short cycle life, and secondly, tetravalent cerium ions have a certain oxidative decomposition effect on organic components, a complexing additive is continuously consumed in long-period operation, the electrolyte composition is changed to further cause capacity attenuation, and furthermore, the titanium cerium flow battery can cause continuous accumulation of tetravalent cerium ions in the positive electrode electrolyte, namely, the trivalent titanium ions in the negative electrode electrolyte are insufficient, the valence state of active ions of the electrolyte is unbalanced, so that the capacity and the cycle life of the battery are reduced. Therefore, how to reduce the side reaction during the operation of the titanium cerium flow battery, delay the decrease of the battery capacity and the decrease of the battery life caused by the accumulation of tetravalent cerium ions has become a urgent problem for those skilled in the art. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide an anode electrolyte and a titanium cerium flow battery, and improve the efficiency and the cycle life of the titanium cerium flow battery. In order to achieve the aim of the invention, the invention adopts the following technical scheme: In a first aspect, the invention provides a positive electrode electrolyte, which is formed by mixing an initial electrolyte and a hydrogen peroxide solution, wherein the initial electrolyte is an acidic aqueous solution containing a supporting electrolyte and cerium ions. According to the invention, the hydrogen peroxide solution is mixed into the initial electrolyte, and as hydrogen peroxide has good reduction performance under an acidic condition, the hydrogen peroxide is used as a reducing agent to react with tetravalent cerium ions generated by the positive electrode in the charging process, so that the tetravalent cerium ions are reduced into trivalent cerium ions, and the continuous accumulation of the tetravalent cerium ions in the positive electrode electrolyte under long circulation is avoided, thereby improving the efficiency and the cycle life of the titanium-cerium flow battery. When the cycle is attenuated to a certain degree, a proper amount of hydrogen peroxide solution can be added into the positive electrode electrolyte to reduce excessive tetravalent cerium ions, so that the purposes of capacity improvement and long-cycle stability are realized. In addition, the decomposition products of the hydrogen peroxide are oxygen and water, other impurities are not introduced in the reactio