Ferrocene-cyclic nitroxide free radical positive electrode electrolyte, preparation method thereof and aqueous flow battery

Abstract

The invention discloses a ferrocene-cyclic nitroxide free radical positive electrode electrolyte, a preparation method thereof and an aqueous flow battery, and belongs to the technical field of energy storage batteries. The positive electrode electrolyte of the flow battery takes ferrocene (Fc) and a derivative thereof as a positive electrode main body material, takes a cyclic nitroxide free radical organic active molecule and a derivative thereof as an active additive material, and is added with the Fc derivative of the cyclic nitroxide free radical organic active molecule; compared with a single Fc electrolyte before addition, the electrolyte has higher oxidation-reduction potential and better stability, and can be matched with a proper negative electrode electrolyte to form a high-voltage and stable aqueous flow battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of large-scale energy storage, and in particular relates to a ferrocene-cyclic nitroxide free radical cathode electrolyte, a preparation method thereof, and an aqueous liquid flow battery. Background Art

[0002] With the continuous development of new energy technologies, the supply of new energy sources such as solar energy, hydropower, wind power and tidal power is increasing. However, these technologies are easily affected by the outside world, have weak risk resistance, and are more susceptible to impact in extreme situations. In addition, the production of new energy sources is highly volatile and the continuous production capacity is insufficient, so new energy storage technologies have become a potential best choice. Electrochemical energy storage has the advantages of high energy efficiency, easy maintenance and good cycle performance, and has been more favored. Compared with lithium-ion batteries, flow batteries have more advantages in safety and design flexibility. They can store energy on a large scale when wind and solar energy are at their peak, and release it when demand is low, providing good support for the promotion of new energy technologies.

[0003] Active substances are important components of flow battery electrolytes, and their usage and stability determine the battery's capacity and service life, respectively. Ferrocene (Fc) molecules are composed of two cyclopentadiene ligands and an iron atom center, and the two rings can rotate freely in the solution. Fc molecules have high redox potential, good reversibility, and abundant sources, making them one of the commonly used active substances in the positive electrolyte of flow batteries. However, Fc molecules have low solubility in water and were used in non-aqueous flow batteries in the early days. With the development of functional group modification and other methods, hydrophilic groups can be introduced on cyclopentadiene, thereby effectively improving its solubility in aqueous solution, which expands the application range of Fc to the molecular system of aqueous flow battery electrolytes. Despite this, water-soluble Fc derivatives still face the problem of frequent side reactions during the charge and discharge process, which leads to molecular inactivation and causes a series of problems such as low battery energy density and rapid capacity decay, thus restricting the development of its large-scale application. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a ferrocene-cyclic nitroxide free radical cathode electrolyte and its preparation method and aqueous liquid flow battery to solve the problem that ferrocene substances are easily degraded and inactivated in water and have low electrochemical stability.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides a ferrocene-cyclic nitroxide free radical positive electrode electrolyte, comprising a positive electrode main body material, an active additive material and a supporting electrolyte; The main material of the positive electrode is ferrocene or a ferrocene derivative; The active additive material is a cyclic nitroxide free radical or a cyclic nitroxide free radical derivative.

[0006] Preferably, the ferrocene derivative is: or

[0007] Wherein, R and R' are both one or a combination of quaternary ammonium salt cation group, phosphate anion group, and sulfonate anion group.

[0008] Preferably, the cyclic nitroxide free radical derivative and the cyclic nitroxide free radical derivative are:

[0009] Wherein, n=0, 1 or 2; R'' is one or a combination of H, halogen, hydroxyl, amino, quaternary ammonium salt cation group, phosphate anion group, sulfonate anion group.

[0010] Preferably, the concentration of the positive electrode main material and the active additive material in the positive electrode electrolyte is 0.001-10 mol / L.

[0011] Preferably, the molar ratio of the positive electrode main material to the active additive material is (1-9):1.

[0012] Preferably, the supporting electrolyte is a salt substance.

[0013] Preferably, the salt substance includes anions and cations: The anion is one or a combination of halide ion, phosphate ion, sulfate ion, perchlorate ion, hexafluorophosphate ion or tetrafluoroborate ion; the cation is one or a combination of alkali metal, alkaline earth metal or quaternary ammonium salt cation.

[0014] The second aspect of the present invention discloses a method for preparing a ferrocene-cyclic nitroxide free radical positive electrode electrolyte, the preparation process comprising: mixing and stirring a positive electrode main body material, an active additive material and a supporting electrolyte to obtain a ferrocene-cyclic nitroxide free radical positive electrode electrolyte; The main material of the positive electrode is ferrocene or a ferrocene derivative; The active additive material is a cyclic nitroxide free radical or a cyclic nitroxide free radical derivative.

[0015] The third aspect of the present invention discloses an aqueous liquid flow battery, comprising a liquid storage tank loaded with a negative electrode electrolyte, a liquid storage tank loaded with the positive electrode electrolyte and a battery stack, wherein an ion exchange membrane is used as a diaphragm in the battery stack; The liquid storage tank loaded with negative electrode electrolyte is connected to the negative electrode, the liquid storage tank loaded with positive electrode electrolyte is connected to the positive electrode, and the diaphragm is arranged between the positive electrode and the negative electrode.

[0016] Preferably, the negative electrode electrolyte is prepared from one or a combination of zinc chloride, viologen, anthraquinone, phenazine, and pteridine materials; the electrode is carbon paper or graphite felt, and the carbon paper or graphite felt is subjected to high-temperature annealing treatment or acid pretreatment; the battery stack is assembled into a copper current collector, a graphite plate flow channel, a carbon paper or graphite felt electrode, a diaphragm, an electrode, a graphite plate flow channel, and a copper current collector.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a positive electrode electrolyte with ferrocene (Fc) or its derivatives as the main positive electrode material and cyclic nitroxide free radical derivatives as active additive materials. The electrolyte adjusts the water environment around the Fc derivative and utilizes the weak interaction between the cyclic nitroxide free radical site and water to inhibit the nucleophilic substitution reaction of water or other species on Fe³⁺ in the molecule, thereby reducing the generation of iron oxides in the degradation product. At the same time, after adding the cyclic nitroxide free radical material, the positive electrode electrolyte of the Fc derivative exhibits a more positive potential and higher stability than when it is not added. Combined with a suitable negative electrode matching, a high-voltage and stable aqueous flow battery can be realized. In addition, since the main components of the cyclic nitroxide free radical active additive materials are carbon, hydrogen, nitrogen, oxygen and other elements, and the sources of these elements are cheap and abundant, the Fc derivative aqueous redox flow battery will significantly reduce the cost in large-scale production compared with the existing heavy metal ion flow batteries such as vanadium, and is suitable for the needs of large-scale energy storage technology.

[0018] The present invention also discloses a method for preparing a ferrocene-cyclic nitroxide free radical cathode electrolyte, which significantly improves the electrochemical stability and redox potential of Fc derivative molecules, and has the advantages of power and energy design flexibility, low cost, simple production process, and scalable assembly and application, and is suitable for large-scale energy storage applications. Compared with other modification methods for the easy degradation of Fc derivatives, this method is simple and flexible to operate and has lower cost. In addition, there is no precedent in the prior art for the assembly and application of aqueous liquid flow batteries using cyclic nitroxide free radical substances as active additives.

[0019] The present invention discloses an aqueous liquid flow battery, which uses one or a combination of zinc chloride, viologen, anthraquinone, phenazine, pteridine and other materials as the negative electrode electrolyte, and uses an Fc derivative added with cyclic nitroxide free radical active additives as the positive electrode electrolyte. In addition, the battery uses an aqueous solution of one or a combination of salt substances as a supporting electrolyte, an anion or cation exchange membrane as a diaphragm, two copper plates as the current collector of the battery, and a graphite plate with a flow channel as the flow field plate of the positive and negative electrodes; finally, carbon paper, graphite felt or metal electrodes are used as electrode materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The cyclic voltammetry test results of FcNCl and TMA-TEMPO solution obtained in Example 1 of the present invention are shown. The cyclic voltammetry test is performed with silver / silver chloride as the reference electrode at a concentration ratio of 9:1, 8:2, 7:3, 6:4, and 5:5 and a scan rate of 100 mV / s.

[0021] Figure 2 The cyclic voltammetry test results of FcNCl and 4-OH-TEMPO solution obtained in Example 1 of the present invention are shown in Figure 1. The cyclic voltammetry test was performed with silver / silver chloride as the reference electrode at concentration ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 and a scan rate of 100 mV / s.

[0022] Figure 3 The aqueous liquid flow battery assembled in Example 2 of the present invention is 50 mA / cm 2 The battery discharge capacity, coulombic efficiency and energy efficiency are shown in the graph after 400 cycles of charge and discharge at a current density of .

[0023] Figure 4 The assembled battery in Example 2 of the present invention is 50 mA / cm 2 Capacity-voltage diagram for different number of charge and discharge cycles at current density.

[0024] Figure 5 The assembled battery in Example 3 of the present invention is 50 mA / cm 2 The battery discharge capacity, coulombic efficiency and energy efficiency are shown in the graph after 400 cycles of charge and discharge at a current density of .

[0025] Figure 6 The assembled battery in Example 3 of the present invention is 50 mA / cm 2 Capacity-voltage diagram for different number of charge and discharge cycles at current density. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings: In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0027] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0028] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0029] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0030] As described in the background technology, in existing aqueous flow batteries, when Fc or Fc derivatives are used as the main material of the positive electrode electrolyte, these substances are easily attacked by water molecules and other species, undergoing nucleophilic reactions, leading to degradation and the production of iron oxide-containing byproducts, thereby making Fc or Fc derivatives less stable. In order to solve the above problems, the present invention introduces cyclic nitroxide free radicals and their derivatives into the positive electrode electrolyte of Fc or Fc derivatives as active additive materials.

[0031] The first aspect of the present invention provides a ferrocene-cyclic nitroxide free radical positive electrode electrolyte, which includes a positive electrode main body material, an active additive material and a supporting electrolyte.

[0032] The main material of the positive electrode is ferrocene (Fc) or a ferrocene derivative, and ferrocene is biscyclopentadienyl iron.

[0033] The active additive material is a water-soluble cyclic nitroxide free radical or a cyclic nitroxide free radical derivative.

[0034] The structural formula of biscyclopentadienyl iron is:

[0035] The structural formula of the ferrocene derivative is: or

[0036] Wherein, R and R' are respectively one or a combination of quaternary ammonium salt cation group, phosphate anion group, and sulfonate anion group.

[0037] The structural formula of the cyclic nitroxide free radical and the cyclic nitroxide free radical derivative is:

[0038] Wherein n=0, 1 or 2; R'' is one or a combination of H, halogen, hydroxyl, amino, quaternary ammonium salt cation group, phosphate anion group, and sulfonate anion group; in this structure, the four ortho-methyl groups next to the nitroxide free radical can stabilize the structure, and the nitroxide free radical can undergo redox reaction.

[0039] Fc is an organic compound containing iron, with the chemical formula Fe(C 5 H 5 ) 2 In aqueous flow batteries, Fc is used as the main material of the positive electrode. Through the redox reaction of iron in the molecular structure, electrical energy can be stored and released. During the charging process, the positive electrode Fc is oxidized, releasing electrons and flowing to the negative electrode through the external circuit. At the same time, the active material of the negative electrode accepts electrons and is reduced, thereby realizing the storage of electrical energy. The discharge process is the opposite of the above-mentioned charging process, thereby realizing the release of electrical energy.

[0040] In the above electrolyte, a positive electrode electrolyte of an Fc derivative containing a cyclic nitroxide free radical molecule is added, and the water environment around the Fc derivative molecule is regulated based on the weak interaction between the nitroxide free radical site in the cyclic nitroxide free radical and water, thereby inhibiting the water molecules or other species from reacting with the Fe in the Fc. 3+ The nucleophilic substitution reaction reduces the generation of degradation products, such as iron oxides. This makes the positive electrode electrolyte of the Fc derivative with the addition of cyclic nitroxide free radical molecules show a more positive potential and higher stability than before mixing. When matched with a suitable negative electrode, a high-voltage and stable aqueous flow battery can be constructed.

[0041] The supporting electrolyte includes any one or a combination of halogen ions, phosphate ions, sulfate ions, hexafluorophosphate ions or tetrafluoroborate ions and compounds selected from alkali metal or alkaline earth metal cations and substituted and unsubstituted ammonium cations.

[0042] As a preferred embodiment, the solubility of the positive electrode main material in water is 0.001-10 mol / L, and the active additive material is not limited in solubility, which can meet the high concentration requirements of the positive electrode main material, thereby increasing the battery capacity.

[0043] As a preferred embodiment, the molar ratio of the positive electrode main material to the active additive material is (1-9):1.

[0044] Compared with other active material modification methods, the active additive material strategy has the following advantages: the properties of the active additive material, such as size and water solubility, can be regulated according to demand, with flexible design and a wide range of choices. It can greatly improve the electrochemical stability of the main cathode material and increase the redox potential, thereby promoting the working performance of aqueous flow batteries and increasing life and power. Active additive materials can also contribute charge storage sites, avoid the introduction of inactive mass increases, and improve the energy density of aqueous flow batteries. Compared with the molecular engineering transformation strategy of functional group modification, the active additive material strategy is simpler and more convenient, has low maintenance costs, and is easier to mass produce and apply.

[0045] The second aspect of the present invention discloses a method for preparing a ferrocene-cyclic nitroxide free radical positive electrode electrolyte. The preparation process of the positive electrode electrolyte is: mixing and stirring the positive electrode main material, active additive material and supporting electrolyte to obtain the ferrocene-cyclic nitroxide free radical positive electrode electrolyte.

[0046] Preferably, the Fc derivative, the cyclic nitroxide free radical or its derivative are weighed and placed in a round-bottom flask, and then a potassium chloride solution is added, mixed and stirred at room temperature to obtain a mixed positive electrode electrolyte.

[0047] The third aspect of the present invention discloses an aqueous flow battery, wherein zinc chloride is used as the negative electrode electrolyte and an Fc derivative to which an active cyclic nitroxide free radical material is added is used as the positive electrode electrolyte, and the weak interaction between the nitroxide free radical site in the cyclic nitroxide free radical derivative and water is used to adjust the water environment around the Fc derivative, thereby inhibiting the activity of water or other species on Fe 3+ nucleophilic substitution reaction to reduce the formation of degradation product iron oxide; one or several combinations of salt substances in aqueous solution are used as electrolyte; anion exchange membrane is used as ion exchange membrane diaphragm; two copper plates are used as current collectors of the battery; graphite plates with flow channels are used as flow field plates for positive and negative electrodes; carbon paper, graphite felt or metal electrodes are used as electrodes of the battery.

[0048] The aqueous liquid flow battery specifically comprises two electrolyte storage tanks, and the two electrolyte storage tanks are isolated and arranged by a liquid flow battery stack; wherein the electrolyte storage tank is a storage tank storing electrolyte.

[0049] A zinc chloride electrolyte is used as the negative electrode, and a positive electrode electrolyte to which an Fc derivative with an active cyclic nitroxide free radical material is added is used as the positive electrode; the battery is assembled in the order of a copper current collector, a graphite plate flow channel, a carbon paper / graphite felt electrode, a zinc sheet, a carbon paper / graphite felt electrode, a diaphragm, an electrode, a graphite plate flow channel, and a copper current collector; the graphite plates of the positive and negative electrodes are respectively connected to two electrolyte storage tanks, and a peristaltic pump is used to deliver the electrolyte in the storage tank into the battery, so that an oxidation-reduction reaction occurs on the electrode, thereby realizing charging and discharging.

[0050] Preferably, the electrode is graphite felt, carbon paper or a metal electrode; the metal electrode is one or a combination of gold electrode, platinum electrode and silver electrode.

[0051] As a preferred embodiment, the electrode material is graphite felt, carbon paper or metal electrode that has been subjected to high temperature insulation annealing or acid pretreatment; the metal electrode is a combination of one or more of a gold electrode, a platinum electrode and a silver electrode.

[0052] The aqueous flow battery is charged and discharged by using a positive electrode electrolyte to which an Fc derivative having an active cyclic nitroxide radical material is added as a positive electrode active material to undergo a redox reaction.

[0053] For aqueous flow batteries, there are the following advantages: Energy and power decoupling design: The energy density of the battery depends on the amount of electrolyte and the concentration of active substances, while the power is related to the effective working area of ​​the battery. This separation design enhances the designability and flexibility of the battery, making it possible to adjust the battery structure according to demand. Environmental friendliness and economy: The new aqueous flow battery mainly uses common elements such as carbon, hydrogen, oxygen, and nitrogen. These elements are naturally abundant and there is basically no environmental pollution after leakage. In theory, they have better economy and environmental protection. Safety: Compared with organic solvents, water pollutes the environment less and does not burn under high temperature or collision conditions. Therefore, aqueous flow batteries have intrinsic safety characteristics. Easy structural adjustment: Organic matter has rich structures and is easier to adjust. By simply adding or modifying functional groups, the electrochemical properties of active substances can be effectively improved, thereby adjusting the working performance of the battery. These characteristics make aqueous flow batteries have advantages in many aspects and are suitable for customized design and application in various scenarios.

[0054] The following is further described in conjunction with the embodiments: Example 1 Taking the ferrocene derivative FcNCl as the basic active substance, different masses of cyclic nitroxide free radical active additive materials TMA-TEMPO and 4-OH-TEMPO were weighed and mixed with it, and the molar ratio of active additive materials to FcNCl was 9:1, 8:2, 7:3, 6:4, and 5:5, respectively. The above mixtures were dissolved in 20 mL of 1 mol / L potassium chloride solution, oscillated and stirred for 0.5 hours, and after forming a uniform solution, a mixed solution with a concentration of 0.05 mol / L was prepared. The positive electrolyte prepared above was subjected to cyclic voltammetry test using a three-electrode system, in which silver / silver chloride was used as the reference electrode, platinum electrode was used as the counter electrode, and glassy carbon electrode was used as the working electrode, and the scan rate was 100 mV / s.

[0055] The structural formulas of the ferrocene derivative FcNCl, the cyclic nitroxide free radical active additive materials TMA-TEMPO and 4-OH-TEMPO are respectively: , ,

[0056] With silver / silver chloride as reference electrode, in the condition of neutral potassium chloride supporting electrolyte, Figure 1 From the cyclic voltammetry curve, it can be seen that the FcNCl electrolyte with TMA-TEMPO added exhibits two pairs of obvious reversible redox peaks, with average redox potentials of about 0.38 V and 0.71 V, respectively. The current response values ​​of the oxidation peak and the reduction peak of the electrolyte molecule are close, indicating good electrochemical reversibility. Figure 2 From the cyclic voltammetry curve, it can be seen that the FcNCl electrolyte with the addition of 4-OH-TEMPO also exhibits similar redox behavior, and the potentials are 0.38 V and 0.59 V, respectively. The above test results show that the positive electrode electrolyte with the addition of active cyclic nitroxide free radical materials has a relatively positive redox potential.

[0057] Example 2 Weigh 0.36 mmol of ferrocene derivative FcNCl and 0.04 mmol of TMA-TEMPO in 8 mL of 1 mol / L potassium chloride solution. The molar ratio of the two is 9:1, and the molar concentrations are 0.045 mol / L and 0.005 mol / L, respectively. Stir and shake until a uniform solution is formed as the positive electrolyte. Take 1 mol / L potassium chloride solution of zinc chloride as the negative electrolyte. After nitrogen is passed through the above electrolyte for deoxygenation for 0.5 hours, add it to the liquid storage tank to form a liquid flow battery device system. Place graphite felt or carbon paper in a muffle furnace at 500 o C for 10 hours, and then taken out after cooling to room temperature for direct use.2 )-anion exchange membrane-carbon paper / graphite felt electrode-graphite plate flow channel-copper current collector in the order and position, and the battery performance test was carried out using a peristaltic pump to drive the electrolyte.

[0058] The aqueous flow battery was tested at 50 mA / cm 2 Long-term cycle performance test was carried out at a current density of Figure 3 , Figure 4 As shown in the figure, the assembled TMA-TEMPO&FcNCl / / Zn full battery exhibited a coulombic efficiency of more than 99% and an energy efficiency of more than 78% within 400 cycles. Figure 3 The relationship between discharge capacity and cycle number shows that the charge and discharge capacity decays slightly in 400 charge and discharge cycles, and the capacity retention rate is 99.94% / cycle. Figure 4 The relationship between discharge capacity and voltage under different numbers of cycles also shows that the battery has a clear charge and discharge voltage platform, but as the number of charge and discharge cycles increases, the charge and discharge platform shortens and changes little, and the battery discharge capacity decreases less.

[0059] Example 3 Weigh 0.3 mmol of ferrocene derivative FcNCl and 0.1 mmol of cyclic nitroxide free radical active additive TMA-TEMPO in 8 ml of 1 mol / L potassium chloride solution. The molar ratio of the two is 3:1, and the molar concentrations are 0.0325 mol / L and 0.0125 mol / L, respectively. Stir for 0.5 hours and use it as the positive electrolyte after forming a uniform solution. Take 1 mol / L potassium chloride solution of zinc chloride as the negative electrolyte. Pass nitrogen gas to deoxygenate the above electrolyte for 0.5 hours, and then add it to the liquid storage tank to form a liquid flow battery device system. Acidify the graphite felt or carbon paper in 300 mL of 1 mol / L dilute hydrochloric acid, stir for 3-5 hours, take it out, wash it with deionized water, and dry it for use. Copper current collector-graphite plate flow channel-carbon paper / graphite felt electrode (5 cm 2 The battery is assembled in the order and position of )-anion exchange membrane-carbon paper / graphite felt electrode-graphite plate flow channel-copper current collector, and the electrolyte is driven by a peristaltic pump for charging and discharging.

[0060] The cell is at 50 mA / cm 2 The long cycle performance test was carried out at a current density of Figure 5 and Figure 6 As shown. Figure 5 It can be seen that the coulombic efficiency of the battery remains above 99%, and the energy efficiency is also relatively stable, remaining at around 84.5%; the curve of discharge capacity changing with the number of cycles shows that the battery capacity retention rate is 99.93% / cycle. Figure 6It represents the relationship between the discharge capacity and voltage of the battery under different cycle numbers. Although the battery has a clear charge and discharge voltage platform, as the number of charge and discharge cycles increases, the charge and discharge platform shortens and accelerates, and the battery discharge capacity decreases.

[0061] Example 4 Take 8 mL of 1 mol / L potassium chloride solution, weigh 0.32 mmol of ferrocene derivative FcNCl and 0.08 mmol of cyclic nitroxide free radical active additive TMA-TEMPO in a beaker, at a molar ratio of 4:1, and molar concentrations of 0.045 mol / L and 0.005 mol / L, respectively, and stir thoroughly to make them uniform. Potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing a battery using the mixed solution is the same as in Example 2.

[0062] Example 5 Take 8 mL of 1 mol / L potassium chloride solution, weigh 0.2 mmol of ferrocene derivative FcNCl and 0.2 mmol of cyclic nitroxide free radical active additive TMA-TEMPO in a beaker. At this time, the molar ratio of the two is 1:1, and the molar concentrations are 0.025 mol / L and 0.025 mol / L respectively. Stir well to make it uniform.

[0063] The potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing the battery using the mixed solution is the same as in Example 2.

[0064] Example 6 Take 8 mL of 1 mol / L potassium chloride solution, weigh 0.36 mmol of ferrocene derivative FcNCl and 0.04 mmol of cyclic nitroxide free radical active additive 4-OH-TEMPO in a beaker. At this time, the molar ratio of the two is 9:1, and the molar concentrations are 0.045 mol / L and 0.005 mol / L respectively. Stir well to make it uniform.

[0065] The potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing the battery using the mixed solution is the same as in Example 2.

[0066] Example 7 Take 8 mL of 1 mol / L potassium chloride solution, weigh 0.2 mmol of ferrocene derivative FcNCl and 0.2 mmol of cyclic nitroxide free radical active additive 4-OH-TEMPO in a beaker. At this time, the molar ratio of the two is 1:1, and the molar concentrations are 0.025 mol / L and 0.025 mol / L respectively. Stir well to make it uniform.

[0067] The potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing the battery using the mixed solution is the same as in Example 2.

[0068] Example 8 Take 8 mL of 1 mol / L potassium chloride solution, weigh 0.008 mmol of ferrocene derivative FcNCl and 0.008 mmol of cyclic nitroxide free radical active additive 4-OH-TEMPO in a beaker. At this time, the molar ratio of the two is 1:1, and the molar concentrations are 0.001 mol / L and 0.001 mol / L respectively. Stir well to make it uniform.

[0069] The potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing the battery using the mixed solution is the same as in Example 2.

[0070] Example 9 Take 8 mL of 1 mol / L potassium chloride solution, weigh 80 mmol of ferrocene derivative FcNCl and 80 mmol of cyclic nitroxide free radical active additive 4-OH-TEMPO in a beaker. At this time, the molar ratio of the two is 1:1, and the molar concentrations are 10 mol / L and 10 mol / L, respectively. Stir well to make them uniform.

[0071] The potassium chloride here can also be replaced by other electrolytes of the same concentration, and the process of preparing the battery using the mixed solution is the same as in Example 2.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A ferrocene-cyclic nitroxide free radical cathode electrolyte, characterized in that: Including positive electrode main material, active additive material and supporting electrolyte; The main material of the positive electrode is ferrocene or a ferrocene derivative; The active additive material is a cyclic nitroxide free radical or a cyclic nitroxide free radical derivative.

2. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 1, characterized in that: The ferrocene derivative is: or Wherein, R and R' are both one or a combination of quaternary ammonium salt cation group, phosphate anion group, and sulfonate anion group.

3. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 1, characterized in that: The cyclic nitroxide free radical derivatives and cyclic nitroxide free radical derivatives are: Wherein, n=0, 1 or 2; R'' is one or a combination of H, halogen, hydroxyl, amino, quaternary ammonium salt cation group, phosphate anion group, sulfonate anion group.

4. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 1, characterized in that: The concentrations of the positive electrode main material and the active additive material in the positive electrode electrolyte are both 0.001-10 mol / L.

5. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 1, characterized in that: The molar ratio of the positive electrode main material to the active additive material is (1-9):

1.

6. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 1, characterized in that: The supporting electrolyte is a salt substance.

7. The ferrocene-cyclic nitroxide free radical cathode electrolyte according to claim 6, characterized in that: The salt substances include anions and cations: The anion is one or a combination of halide ion, phosphate ion, sulfate ion, perchlorate ion, hexafluorophosphate ion or tetrafluoroborate ion; the cation is one or a combination of alkali metal, alkaline earth metal or quaternary ammonium salt cation.

8. A method for preparing a ferrocene-cyclic nitroxide free radical cathode electrolyte, characterized in that: The preparation process is as follows: a cathode main material, an active additive material and a supporting electrolyte are mixed and stirred to obtain a ferrocene-cyclic nitroxide free radical cathode electrolyte; The main material of the positive electrode is ferrocene or a ferrocene derivative; The active additive material is a cyclic nitroxide free radical or a cyclic nitroxide free radical derivative.

9. An aqueous liquid flow battery, characterized in that: It comprises a liquid storage tank loaded with a negative electrode electrolyte, a liquid storage tank loaded with the positive electrode electrolyte according to claim 1, and a battery stack, wherein an ion exchange membrane is used as a diaphragm in the battery stack; The liquid storage tank loaded with negative electrode electrolyte is connected to the negative electrode, the liquid storage tank loaded with positive electrode electrolyte is connected to the positive electrode, and the diaphragm is arranged between the positive electrode and the negative electrode.

10. An aqueous liquid flow battery according to claim 9, characterized in that: The negative electrode electrolyte is prepared from one or a combination of zinc chloride, viologen, anthraquinone, phenazine, and pteridine materials; the electrode is carbon paper or graphite felt, and the carbon paper or graphite felt is subjected to high-temperature annealing treatment or acid pretreatment; the battery stack is assembled into a copper current collector, a graphite plate flow channel, a carbon paper or graphite felt electrode, a diaphragm, an electrode, a graphite plate flow channel, and a copper current collector.

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