A positive electrode material of a flow battery and a preparation method and application thereof

Abstract

The application discloses a kind of positive electrode material of liquid flow battery and its preparation method and application.The positive electrode material of the liquid flow battery is TEMPO free radical derivative, the TEMPO free radical derivative has structure shown in formula I, it is prepared by being reacted by being dissolved in solvent with 4-(N,N-dimethylamino)-TEMPO and organic halide.The positive electrode material of the liquid flow battery is adopted in the application, methyl viologen or its derivative is used as the negative electrode material of the liquid flow battery, can obtain the liquid flow battery with the outstanding advantages such as strong stability, good security, flexible configuration, fast response, green environmental protection, high capacity, stable charge-discharge performance, etc., provides powerful support for the application of large-scale energy storage technology.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a positive electrode material for flow batteries, its preparation method, and its application. Background Technology

[0002] Flow batteries are a novel green energy storage technology, favored for their high energy conversion efficiency, long lifespan, adjustable capacity for different applications, high safety, and environmental friendliness. These batteries show great potential for application in wind, solar, and power systems.

[0003] There are many types of flow batteries, but the most mature type currently is the vanadium-based flow battery. It utilizes the redox reactions of vanadium ions in different valence states on the electrode surface to store and release electrical energy. However, vanadium-based flow batteries have some drawbacks, such as lower energy density, higher operating temperature requirements, and higher cost. These limitations restrict their wider application.

[0004] To address the shortcomings of vanadium-based flow batteries, researchers have developed a TEMPO-based flow battery. TEMPO (2,2,6,6-tetramethylpiperidine-1-oxo radical), an organic molecule, is used as a cathode material in flow batteries due to its stability in aqueous solution and reversible redox properties. TEMPO-based flow batteries demonstrate potential as a replacement for traditional vanadium-based flow batteries due to their lower cost and environmental friendliness. However, TEMPO-based flow batteries also face some challenges in practical applications. For example, water-soluble TEMPO molecules are prone to autocatalytic oxidation and ring-opening side reactions during charge and discharge. These side reactions can lead to degradation or deactivation of the TEMPO molecular structure, thus affecting battery performance and lifespan. Capacity decay and shortened lifespan have become one of the main bottlenecks for the large-scale application of TEMPO-based flow batteries.

[0005] Therefore, developing novel TEMPO-based flow battery cathode materials and their preparation methods to improve their capacity, stability, and cycle life is of great significance for promoting the development of flow battery technology. Summary of the Invention

[0006] To overcome the above-mentioned prior art, the present invention discloses a positive electrode material for flow batteries, its preparation method and application.

[0007] In a first aspect, the present invention provides a TEMPO radical derivative having the structure shown in Formula I:

[0008]

[0009] Where X is a halogen (such as F, Cl, Br, I);

[0010] The number of n varies with the structure of A;

[0011] A is selected from the following structure:

[0012]

[0013] Where R is C1-C 10 alkyl;

[0014] a is an integer from 0 to 60 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60);

[0015] b is an integer from 0 to 60 (e.g., 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60);

[0016] a+b is greater than or equal to 1.

[0017] Furthermore, X is Cl, Br, or I.

[0018] Furthermore, n is an integer from 2 to 4 (e.g., 2, 3, 4); preferably, when A is... When n is 3; preferably, when A is When n is 4; preferably, when A is When n is 3; preferably, when A is When n is 2.

[0019] Further, R is a C1-C6 alkyl group; preferably, R is a C1-C4 alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl; more preferably, R is methyl.

[0020] Further, a is an integer from 0 to 30; preferably, a is an integer from 1 to 10; more preferably, a is 5.

[0021] Further, b is an integer from 0 to 30; preferably, b is an integer from 1 to 10; preferably, b is 6.

[0022] Furthermore, the TEMPO radical derivative has the following structure:

[0023]

[0024] In some embodiments of the present invention, the TEMPO radical derivative has the following structure:

[0025]

[0026]

[0027] A second aspect of the present invention provides a method for preparing the TEMPO radical derivative described in the first aspect of the present invention, the method comprising the following steps: reacting 4-(N,N-dimethylamino)-TEMPO and an organohalide in a solvent to obtain the TEMPO radical derivative;

[0028] The organohalides are selected from the following structures:

[0029]

[0030] Wherein, X, R, a, and b have the definitions described in the first aspect of the present invention.

[0031] Furthermore, the solvent is selected from one or more of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, methanol, and ethanol, preferably N,N-dimethylformamide or ethanol.

[0032] Furthermore, a catalyst may be added to the reaction.

[0033] Furthermore, the catalyst is selected from one or more of sodium iodide, potassium iodide, cesium iodide, cuprous iodide, tetrabutylammonium iodide, aluminum iodide, zinc iodide, hydrogen iodide and sodium periodate, preferably sodium iodide or potassium iodide.

[0034] Further, the molar ratio of 4-(N,N-dimethylamino)-TEMPO to halogen in the organohalide is (0.8-1.2):1, such as 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, preferably (0.95-1.05):1.

[0035] Further, the molar ratio of 4-(N,N-dimethylamino)-TEMPO to the catalyst is (5-1000):1, such as 5:1, 10:1, 20:1, 50:1, 100:1, 200:1, 500:1, 1000:1, preferably (50-100):1.

[0036] Further, the reaction temperature is 60-180℃, such as 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180℃, preferably 60-150℃, and more preferably 60-90℃.

[0037] Further, the reaction time is 6-36 hours, such as 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 hours, preferably 6-24 hours, and more preferably 12-24 hours.

[0038] A third aspect of the present invention provides an application of the TEMPO radical derivative described in the first aspect of the present invention or the TEMPO radical derivative prepared by the preparation method described in the second aspect of the present invention as a positive electrode material for a flow battery.

[0039] In a fourth aspect, the present invention provides a flow battery system comprising a positive electrode reservoir, a negative electrode reservoir, and a flow battery stack; the two ends of the flow battery stack are respectively connected to the positive electrode reservoir and the negative electrode reservoir.

[0040] Furthermore, the positive electrode storage tank is a storage tank containing positive electrode electrolyte, and the negative electrode storage tank is a storage tank containing negative electrode electrolyte.

[0041] Furthermore, the positive electrode electrolyte contains a positive electrode material and a supporting electrolyte, and the negative electrode electrolyte contains a negative electrode material and a supporting electrolyte.

[0042] Furthermore, the positive electrode material and the negative electrode material are respectively dissolved or dispersed directly in a system using water as a solvent in bulk form.

[0043] Furthermore, the cathode material is the TEMPO radical derivative described in the first aspect of the present invention or the TEMPO radical derivative prepared by the preparation method described in the second aspect of the present invention.

[0044] Furthermore, the negative electrode material is methyl viologen and / or a derivative of methyl viologen.

[0045] Further, the concentrations of the positive electrode material and the negative electrode material are 0.05-3 mol / L, such as 0.05, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, and 3 mol / L; preferably, the concentrations of both the positive electrode material and the negative electrode material are 0.1 mol / L.

[0046] Further, the supporting electrolyte is selected from one or more of NaCl aqueous solution, KCl aqueous solution, Na2SO4 aqueous solution, K2SO4 aqueous solution, MgCl2 aqueous solution, MgSO4 aqueous solution, CaCl2 aqueous solution and NH4Cl aqueous solution; preferably, the supporting electrolyte is NaCl aqueous solution or KCl aqueous solution.

[0047] Further, the concentration of the supporting electrolyte is 0.1-8 mol / L, such as 0.1, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8 mol / L; preferably, the concentration of the supporting electrolyte is 1 mol / L.

[0048] Furthermore, the positive electrode storage tank and the negative electrode storage tank are pressurized sealed containers with a pressure of 0.1-0.5 MPa.

[0049] Furthermore, inert gas (such as argon) is introduced into the positive electrode storage tank and the negative electrode storage tank for purging and pressure maintenance.

[0050] Furthermore, the flow battery stack includes a battery separator; the battery separator divides the flow battery stack into a positive electrode region and a negative electrode region; the positive electrode region is connected to a positive electrode storage tank, and the negative electrode region is connected to a negative electrode storage tank; a positive electrode current collector is installed in the positive electrode region, and a negative electrode current collector is installed in the negative electrode region.

[0051] Furthermore, the positive electrode region is connected to the positive electrode storage tank via a positive electrode circulation pipeline, and the negative electrode region is connected to the negative electrode storage tank via a negative electrode circulation pipeline.

[0052] Furthermore, the battery separator is a cation exchange membrane, an anion exchange membrane, a selectively permeable membrane, or a polymer porous membrane.

[0053] Furthermore, the battery separator can allow the supporting electrolyte to pass through while preventing the positive and negative active materials from passing through.

[0054] Furthermore, the current collector can collect and conduct the current generated by the active material of the flow battery stack to external wires.

[0055] Furthermore, the current collector is a conductive metal plate, a graphite plate, or a carbon-plastic composite plate.

[0056] Furthermore, the conductive metal plate contains at least one metal selected from copper, nickel, and aluminum.

[0057] Furthermore, electrodes are respectively provided in the positive electrode region and the negative electrode region. The electrodes are carbon material electrodes, which are selected from one or more of carbon felt, carbon paper, carbon cloth, carbon black, activated carbon fiber, activated carbon particles, graphene, graphite felt and glassy carbon materials.

[0058] Furthermore, the electrode is formed as an electrode plate.

[0059] Furthermore, the flow battery system also includes a pump system for delivering the electrolyte.

[0060] Furthermore, the pump set is a peristaltic pump, a mechanical pump, or a magnetic pump.

[0061] The present invention has the following beneficial effects:

[0062] The TEMPO radical derivative of this invention can be used as the positive electrode material of a flow battery. This TEMPO radical derivative is characterized by low cost and ease of synthesis. By using the TEMPO radical derivative as the positive electrode material and methyl viologen or its derivatives as the negative electrode material in this invention, a flow battery with outstanding advantages such as high stability, good safety, flexible configuration, fast response, environmental friendliness, high capacity, and stable charge-discharge performance can be obtained, providing strong support for the application of large-scale energy storage technology. Detailed Implementation

[0063] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0064] The term "alkyl" refers to a straight-chain or branched hydrocarbon radical that does not contain unsaturated bonds and is connected to the rest of the molecule by single bonds. Typical alkyl groups contain 1 to 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) carbon atoms, preferably 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, isohexyl, etc. In this invention, CO alkyl refers to H, i.e., C 0-10 Alkyl (or C0-C) 10 Alkyl groups include H and C.1-10 Alkyl (or C1-C) 10 alkyl).

[0065] The term "halogen" refers to fluorine, chlorine, bromine, or iodine.

[0066] In this article, the term "4-(N,N-dimethylamino)-TEMPO" is short for 4-(N,N-dimethylamino)-2,2,6,6-tetramethylpiperidine-1-oxy, and its chemical formula is […].

[0067] All publications, patents, and published patent specifications cited in this article are incorporated herein in their entirety through citation.

[0068] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] Preparation example:

[0070] Ingredient 1:

[0071] Ingredient 2:

[0072] Add 1 mol of raw material 1 to a high-pressure reactor, purge with nitrogen three times, add 200 mL of methanol, control the reactor temperature at 10°C, add 1% by weight of Raney-Ni catalyst (based on raw material 1), introduce 2 mol of raw material 2, raise the temperature to 60°C, control the pressure at 4 MPa-4.5 MPa, after the hydrogen absorption interval of the system is greater than 15 min, raise the temperature to 70°C until the final reaction temperature reaches 95°C, stop hydrogen addition, cool down, and discharge to obtain intermediate 1.

[0073] Intermediate 1 was transferred to a four-necked flask, and 2% sodium tungstate (based on intermediate 1) was added and dispersed evenly. The temperature was raised to 60°C, and 8% hydrogen peroxide (based on intermediate 1) was slowly added. The mixture was kept at this temperature for 8 hours. Excess hydrogen peroxide was reduced with sodium sulfite aqueous solution. After the reaction was complete, compound A1 was obtained.

[0074] Example 1:

[0075] Ingredient 1-1: (i.e., compound A1 in the preparation example)

[0076] Raw materials 1-2:

[0077] Product 1:

[0078] Take 1.05 mol of raw material 1-1, disperse it in 500 mL of ethanol, add 0.3 mol of raw material 1-2, add 10% molar potassium iodide (based on raw material 1-1), heat to 70 °C, react for 12 h, concentrate, and obtain target product 1.

[0079] Molecular weight: 953;

[0080] Yield: 94.4%.

[0081] Example 2:

[0082] Raw material 2-1: (i.e., compound A1 in the preparation example)

[0083] Raw material 2-2:

[0084] Product 2:

[0085] Take 1.2 mol of raw material 2-1, disperse it in 600 mL of ethanol, add 0.31 mol of raw material 2-2, add 10% molar sodium iodide (based on raw material 2-1), heat to 60 °C, react for 16 h, concentrate, and obtain target product 2.

[0086] Molecular weight: 1213;

[0087] Yield: 95.7%.

[0088] Example 3:

[0089] Ingredient 3-1: (i.e., compound A1 in the preparation example)

[0090] Raw material 3-2:

[0091] Product 3:

[0092] Take 1.2 mol of raw material 3-1, disperse it in 600 mL of ethanol, add 0.4 mol of raw material 3-2, heat to 60 °C, react for 24 h, concentrate, and obtain the target product 3.

[0093] Molecular weight: 1134;

[0094] Yield: 96.9%.

[0095] Example 4:

[0096] Raw material 4-1: (i.e., compound A1 in the preparation example)

[0097] Raw material 4-2:

[0098] Product 4:

[0099] Take 1.2 mol of raw material 4-1, disperse it in 600 mL of N,N-dimethylformamide, add 0.7 mol of raw material 4-2, heat to 90 °C, react for 16 h, concentrate, and obtain the target product 4.

[0100] Molecular weight: 1049;

[0101] Yield: 92.1%.

[0102] Comparative Example 1:

[0103] The following compound was prepared according to the preparation method in Example 7 of patent document CN115732731A:

[0104]

[0105] Tempo (CAS No. 2226-96-2, 20 g), 1-bromo-3-chloropropane (21.94 g), tetrabutylammonium bromide (37.43 g), and sodium hydroxide aqueous solution (15.5 g, 30%) were added to xylene (400 mL). The reaction mixture was reacted at 25 °C for 48 hours. After the reaction was completed, the reaction mixture was washed with water, and the organic layer was dried over anhydrous sodium sulfate and the solvent was removed by vacuum distillation. The intermediate 4-[3-chloro-propoxy]-2,2,6,6-tetramethylpiperidine-1-oxy was obtained after purification.

[0106] Intermediate 4-[3-chloro-propoxy]-2,2,6,6-tetramethylpiperidin-1-oxy (5 g) and 4-(N,N-dimethylamino)-2,2,6,6-tetramethylpiperidin-1-oxy (4.21 g) were added to ethanol (50 mL) and refluxed for 5 h. After the reaction was completed, the solvent was removed, recrystallized, and dried to obtain the product N-(3-Tempooxypropyl)-N,N-dimethyl-N-Tempoammonium chloride.

[0107] Test Example 1: Electrochemical Performance Test

[0108] This experiment tests electrochemical performance by assembling single-cell batteries, where the measured geometric area of ​​the battery is 2*2cm². 2 The battery separator uses HoAM G-1204 anion exchange membrane, which is directly immersed in 1 mol / L NaCl aqueous solution for 1 hour before use; the battery test mold is provided by Wuhan Chuxin Technology Co., Ltd.; the positive electrode electrolyte is 0.1 mol / L positive electrode active material + 1 mol / L NaCl aqueous solution; the negative electrode electrolyte is methyl viologen + 1 mol / L NaCl aqueous solution.

[0109] The assembled flow batteries were subjected to cycle stability tests at room temperature (25℃). The testing equipment was a Shenzhen Xinwei Battery Tester, with the test voltage set to 0.1-1.7V and the flow rate to 25mL / min.

[0110] in,

[0111] 1# is I-1 of a TEMPO radical cathode material I (prepared from Example 1);

[0112] 2# is I-2 of a TEMPO radical cathode material I (prepared from Example 2);

[0113] 3# is I-3 of a TEMPO radical cathode material I (prepared from Example 3);

[0114] 4# is I-4 of a TEMPO radical cathode material I (prepared from Example 4);

[0115] 5# is I-5 of a TEMPO radical cathode material I (prepared from Comparative Example 1);

[0116] Its electrochemical properties are as follows:

[0117] Table 1: Comparison of Electrochemical Performance

[0118]

[0119] 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, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0120] The foregoing embodiments and methods described in this invention may vary based on the capabilities, experience, and preferences of those skilled in the art.

[0121] Listing the steps of the method in a certain order in this invention does not constitute any restriction on the order of the method steps.

Claims

1. A TEMPO radical derivative, characterized in that, The TEMPO radical derivative has the structure shown in Formula I: Where X is a halogen; The number of n varies with the structure of A; A is selected from the following structure: Where R is C1-C 10 alkyl; a is an integer between 0 and 60; b is an integer between 0 and 60; a+b is greater than or equal to 1.

2. The TEMPO radical derivative according to claim 1, characterized in that, X is Cl, Br, or I; Preferably, when A is When n is 3; Preferably, when A is When n is 4; Preferably, when A is When n is 3; Preferably, when A is When n is 2.

3. The TEMPO radical derivative according to claim 1, characterized in that, R is a C1-C6 alkyl group; preferably, R is a C1-C4 alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl; more preferably, R is methyl. Preferably, a is an integer from 0 to 30; more preferably, a is an integer from 1 to 10. Preferably, b is an integer from 0 to 30, and more preferably, b is an integer from 1 to 10.

4. The TEMPO radical derivative according to any one of claims 1-3, characterized in that, The TEMPO radical derivative has the following structure:

5. The TEMPO radical derivative according to claim 1, characterized in that, The TEMPO radical derivative has the following structure:

6. A method for preparing the TEMPO radical derivative as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: dissolving 4-(N,N-dimethylamino)-TEMPO and an organic halide in a solvent and reacting them to obtain the TEMPO radical derivative; The organohalides are selected from the following structures: Wherein, X, R, a, and b have the definitions as described in any one of claims 1-5.

7. The preparation method according to claim 6, characterized in that, The solvent is selected from one or more of N,N-dimethylformamide, acetonitrile, dimethyl sulfoxide, methanol and ethanol, preferably N,N-dimethylformamide or ethanol; Preferably, a catalyst is also added to the reaction; Preferably, the catalyst is selected from one or more of sodium iodide, potassium iodide, cesium iodide, cuprous iodide, tetrabutylammonium iodide, aluminum iodide, zinc iodide, hydrogen iodide and sodium periodate, and is preferably sodium iodide or potassium iodide.

8. The preparation method according to claim 6, characterized in that, The molar ratio of 4-(N,N-dimethylamino)-TEMPO to halogen in the organohalide is (0.8-1.2):1, preferably (0.95-1.05):1; Preferably, the molar ratio of 4-(N,N-dimethylamino)-TEMPO to the catalyst is (5-1000):1, more preferably (50-100):1; Preferably, the reaction temperature is 60-180℃, more preferably 60-150℃; Preferably, the reaction time is 6-36 hours, more preferably 6-24 hours.

9. The application of a TEMPO radical derivative as described in any one of claims 1-5 or a TEMPO radical derivative prepared by the preparation method as described in any one of claims 6-8 as a positive electrode material for a flow battery.

10. A flow battery system, the flow battery system comprising a positive electrode reservoir, a negative electrode reservoir, and a flow battery stack; the two ends of the flow battery stack are respectively connected to the positive electrode reservoir and the negative electrode reservoir; the positive electrode reservoir contains a positive electrode material, the positive electrode material being a TEMPO radical derivative as described in any one of claims 1-5 or a TEMPO radical derivative prepared by the preparation method as described in any one of claims 6-8.

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