Piperidinyloxy radical derivatives, methods of preparation, and use in flow batteries

Abstract

This invention provides a piperidine oxidative radical derivative, its preparation method, and its application in a flow battery, relating to the field of flow battery technology. The preparation method includes adding triacetoneamine, cyclohexanone, ammonium chloride, and dimethyl sulfoxide to container A, reacting at 68°C for 24 hours, cooling to room temperature, extracting with ethyl acetate, purifying by column chromatography, and recrystallizing from ethanol to obtain a yellow needle-like solid; adding the obtained yellow needle-like solid, sodium borohydride, and ethanol to container B, reacting at room temperature for three hours, diluting with deionized water, extracting with dichloromethane, and drying by rotary evaporation to obtain a white flaky solid; adding the obtained white flaky solid, m-chloroperoxybenzoic acid, and ethanol to container C, reacting in an ice bath for three hours, washing with sodium carbonate solution, extracting with dichloromethane, and purifying by column chromatography to obtain the target product. The piperidine oxidative radical derivative obtained by this invention has strong stability, avoiding the easy degradation defects of ferrocene and other existing technologies.

Description

Technical Field

[0001] This invention relates to the field of flow battery technology, specifically to a piperidine oxidase radical derivative, its preparation method, and its application in flow batteries. Background Technology

[0002] The surge in population and rapid economic development have led to a huge demand for energy. Fossil fuels are typical non-renewable energy sources, and their consumption generates large amounts of greenhouse gases, resulting in an increasingly prominent environmental crisis.

[0003] To reduce dependence on fossil fuels, developing renewable energy sources has gradually become a consensus. Examples include solar, wind, and tidal energy. However, renewable energy generally depends heavily on natural conditions, exhibiting significant intermittency and instability. Unstable power input can easily impact the power grid, potentially leading to grid accidents, which is a major factor restricting the large-scale deployment and application of renewable energy.

[0004] Redox flow batteries (RFBs) have become one of the main ways to address the intermittency and instability of renewable energy sources due to their ability to independently scale energy and power, high safety and high efficiency.

[0005] However, current research on organic electrolytes in flow batteries mostly focuses on negative electrode materials, while the development of positive electrode materials is relatively lacking. The types that have been developed are mostly ferrocene and TEMPO, but both of these positive electrode electrolytes are prone to degradation and cannot meet the needs of practical applications.

[0006] Therefore, there is an urgent need to provide a cathode material for aqueous organic flow batteries to solve the technical problem of easy degradation of ferrocene, TEMPO and other materials in the existing technology. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a piperidine oxidative radical derivative, its preparation method, and its application in flow batteries, solving the technical problem of easy degradation of ferrocene, TEMPO, and other materials used as positive electrode materials in flow batteries.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] In a first aspect, the present invention provides a piperidine oxidative radical derivative having the following structural formula:

[0010]

[0011] A second aspect of the present invention provides a method for preparing the above-mentioned piperidine oxidative radical derivative, the method comprising:

[0012] Triacetone amine, cyclohexanone, and ammonium chloride in a molar ratio of 1:3:6 were added to container A, and a target amount of dimethyl sulfoxide was added as a solvent to obtain a mixture. The mixture was reacted at 68°C for 24 hours under an inert gas atmosphere. After cooling to room temperature, it was extracted with ethyl acetate, purified by column chromatography, and recrystallized from ethanol to obtain a yellow needle-like solid.

[0013] The obtained yellow needle-like solid, sodium borohydride, and ethanol were added to container B and reacted at room temperature for three hours. After dilution with deionized water, the mixture was extracted with dichloromethane and dried by rotary evaporation to obtain a white scaly solid. The molar ratio of the yellow needle-like solid to sodium borohydride was 1:1.

[0014] The obtained white flaky solid, m-chloroperoxybenzoic acid, and ethanol were added to container C. The mixture was reacted in an ice bath for three hours, washed with sodium carbonate solution, extracted with dichloromethane, and purified by column chromatography to obtain the target product. The molar ratio of the white flaky solid to m-chloroperoxybenzoic acid was 1:2.

[0015] A third aspect of the present invention also provides a method for improving the water solubility of the above-mentioned piperidine oxidative radical derivative, the method comprising:

[0016] Piperidine oxidative radical derivatives and cavity coatings in a molar ratio of 1:1 to 10 were added together to deionized water, and after stirring or ultrasonic treatment, a complex with high water solubility was obtained.

[0017] The cavity coating is one or more of α-cyclodextrin, α-cyclodextrin derivatives, β-cyclodextrin, β-cyclodextrin derivatives, γ-cyclodextrin, and γ-cyclodextrin derivatives.

[0018] In a fourth aspect, the present invention also provides the application of the above-mentioned piperidine oxidative radical derivative in a non-aqueous organic flow battery.

[0019] Furthermore, the above applications include using the aforementioned piperidine oxidative radical derivative as a positive electrode electrolyte.

[0020] Furthermore, the negative electrode electrolyte in the non-aqueous organic flow battery is one of N-methylphthalimide, 2,3,6-trimethylquinoxaline, and tetralithium-dinaphthalene-3,4,9,10-tetracarboxylate.

[0021] Furthermore, the electrolyte in the non-aqueous organic flow battery is LiTFSI or LiPF6.

[0022] Furthermore, the solvent in the non-aqueous organic flow battery is acetonitrile or propylene carbonate.

[0023] A fifth aspect of the invention also provides the application of the above-described composite in aqueous or non-aqueous organic flow batteries.

[0024] Furthermore, the above applications include using the above-mentioned composite as a positive electrode electrolyte.

[0025] The present invention provides a piperidine oxidative radical derivative, its preparation method, and its application in a flow battery. Compared with the prior art, it has the following advantages:

[0026] By introducing two six-membered rings on either side of the active site of the TEMPO molecule, replacing the original four methyl groups, the active site of the TEMPO molecule is effectively protected, improving the cycle stability of the resulting flow battery. Furthermore, the molecular size of the resulting derivative is significantly larger than that of the TEMPO molecule, reducing the transmembrane permeability of the positive electrode electrolyte and increasing battery life. The resulting derivative also exhibits a higher electrode potential, which is expected to significantly broaden the operating voltage range of flow batteries. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a CV curve of the electrolyte formed by using 4-OH-DICPO as the positive electrode electrolyte obtained in Example 1 of the present invention at different scan rates.

[0029] Figure 2 This is a CV curve of the electrolyte formed by using the coating 4-OH-DICPO obtained in Example 2 of the present invention as the positive electrode electrolyte, which is continuously scanned 1000 times at 100mV / s.

[0030] Figure 3 The coating obtained in Example 2 of this invention CV curves of the electrolyte formed as the positive electrode electrolyte at different scan rates.

[0031] Figure 4 The coating obtained in Example 2 of this invention The CV curve of the electrolyte formed as the positive electrode electrolyte is continuously scanned 1000 times at 100mV / s.

[0032] Figure 5 This is the 0.1M obtained in Example 2 of the present invention. / BTMAP-Vi Neutral Aqueous Organic Flow Battery Capacity Decay and Efficiency Plots.

[0033] Figure 6 The coating obtained in Example 3 of this invention CV curves of the electrolyte formed as the positive electrode at different scan rates.

[0034] Figure 7 This is the result of Embodiment 3 of the present invention. The CV curve of the electrolyte formed as the positive electrode electrolyte is continuously scanned 1000 times at 100mV / s.

[0035] Figure 8 The coating obtained in Example 4 of this invention CV curves of the electrolyte formed as the positive electrode electrolyte at different scan rates. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0037] To address the issue of easy degradation when ferrocene, TEMPO, and other materials are used as cathode materials in existing flow batteries, the overall approach of this application is as follows:

[0038] A piperidine oxidase radical derivative is provided, with the following structural formula:

[0039]

[0040] This piperidine oxidative radical derivative replaces the four methyl groups on both sides of the TEMPO active site with a six-membered ring with greater steric hindrance, which plays a protective role for the electrochemical active site (i.e. nitroxide radical). Moreover, the molecular size of this derivative is significantly larger than that of other TEMPO derivative molecules. When used as a positive electrode material in flow batteries, it can reduce the transmembrane permeability of the positive electrode electrolyte, which helps to increase the battery life and can greatly improve the cycle stability of the battery.

[0041] Secondly, the complex formed by the piperidine oxide radical derivative and the cavity coating has high water solubility, and the complex can be used as a positive electrode material for aqueous organic flow batteries; therefore, the piperidine oxide radical derivative is of great significance to the development of flow batteries.

[0042] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0043] Example 1

[0044] Preparation of piperidine oxidative radical derivatives with structural formula 1

[0045]

[0046] Its preparation methods include:

[0047] (1) Add 8.00g of triacetoneamine, 15.20g of cyclohexanone, 53.49g of ammonium chloride and 28.00ml of dimethyl sulfoxide to a 100ml single-necked flask to obtain a mixture;

[0048] The mixture was reacted at 68°C for 24 hours under an inert gas atmosphere (argon or nitrogen, argon in this example). After cooling to room temperature, 50.00 ml of deionized water was added to the system and stirred for 30 minutes. Then, 2.00 ml of concentrated hydrochloric acid was added, and the mixture was washed twice with 100.00 ml of methyl tert-butyl ether. The aqueous phase was collected, and NaOH aqueous solution was added to adjust the pH to >9. A yellow precipitate was formed, which was extracted with ethyl acetate, purified by column chromatography, and recrystallized from ethanol to obtain 1.20 g of yellow needle-like solid.

[0049] (2) Dissolve 0.50g of the above yellow needle-like solid in 40.00ml of ethanol, slowly add 0.50g of sodium borohydride, react at room temperature for 3 hours, dilute with 150.00ml of deionized water, extract twice with 20.00ml of dichloromethane, and obtain a viscous liquid by rotary evaporation. After vacuum drying, obtain 0.41g of white scaly solid.

[0050] (3) Dissolve 0.40g of the above white flake-like solid in a three-necked flask containing 7.00ml of dichloromethane. Place the flask in an ice bath under an inert gas atmosphere. Weigh 0.80g of m-chloroperoxybenzoic acid and dissolve it in 10.00ml of dichloromethane. Add the solution dropwise to the three-necked flask through a dropping funnel. React for 3 hours. After the reaction is complete, wash with sodium carbonate solution. Extract the aqueous phase with dichloromethane and purify by column chromatography to obtain 0.18g of orange solid (target product, piperidine oxidative radical derivative, named 4-OH-DICPO).

[0051] Performance verification

[0052] like Figure 1The figure shows the cyclic voltammetry curves of the electrolyte formed by using 4-OH-DICPO prepared in Example 1 as the positive electrode electrolyte. 4-OH-DICPO was dissolved in acetonitrile solution, the supporting electrolyte was 2.00 M LiTFSI, and the concentration of 4-OH-DICPO was 0.01 mol / L. A three-electrode system was used: a glassy carbon electrode with a diameter of 3 mm as the working electrode, a platinum electrode as the counter electrode, and a silver chloride electrode (2.00 M LiTFSI) as the reference electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, and 100 mV / s, respectively.

[0053] Depend on Figure 1 It can be seen that the electrolyte composed of 0.01 mol / L 4-OH-DICPO, 2.00 mol / L LiTFSI, and acetonitrile exhibits a pair of reversible redox peaks at different scan rates, with good reproducibility at different scan rates. This indicates that the 4-OH-DICPO prepared in Example 1 of this invention has good electrochemical reversibility when used as the positive electrode electrolyte, with an electrode potential of +0.7431 V vs SHE (SHE stands for standard hydrogen electrode), which helps to significantly broaden the operating voltage range of the flow battery.

[0054] Figure 2 The figure shows the cyclic voltammogram of an electrolyte consisting of 0.01 mol / L 4-OH-DICPO, 2.00 mol / L LiTFSI, and acetonitrile, scanned for 1000 cycles at a scan rate of 100 mV / s. All curves in the figure show good overlap, indicating that the 4-OH-DICPO prepared in Example 1 has good electrochemical stability when used as a positive electrode electrolyte.

[0055] Example 2

[0056] Weigh 0.13 g of 4-OH-DICPO and add it to a beaker. Weigh 3.64 g of hydroxypropyl-β-cyclodextrin (HP-β-CD) and add it to the beaker. Add 5 ml of deionized water and stir until completely dissolved. This will prepare a 0.01 M 4-OH-DICPO coating with 3 times the amount of HP-β-CD. Weigh out another 0.58g of NaCl and add it to the beaker, stirring until completely dissolved to prepare a solution of 0.01mol / L NaCl. An electrolyte consisting of 2.00 mol / L NaCl and deionized water.

[0057] Performance verification

[0058] Figure 3 The image shown is of the product prepared in Example 2 of this invention. Cyclic voltammetry curves of an electrolyte composed of NaCl and deionized water, where the positive electrode electrolyte is... It dissolves in an aqueous sodium chloride solution with a sodium chloride concentration of 2.00 mol / L. The concentration was 0.01 mol / L. A three-electrode system was used, with a 3 mm diameter glassy carbon electrode as the working electrode, a platinum electrode as the counter electrode, and a silver chloride electrode (3.50 M KCl solution, reference electrode potential +0.2046 V) as the reference electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, and 100 mV / s. Figure 3 It can be seen that the prepared 0.01M The electrolyte composed of 2.00M NaCl and deionized water exhibited a pair of reversible redox peaks at different scan rates, demonstrating good reproducibility at different scan rates. This indicates that the electrolyte prepared in Example 2 of this invention... When used as a positive electrode electrolyte, it exhibits good electrochemical reversibility, with an electrode potential of +0.8236V vs SHE, which is an improvement over the electrode potential of 4-OH-DICPO.

[0059] Figure 4 The image shows the preparation of 0.01 mol / L Cyclic voltammetry was performed on an electrolyte consisting of 2.00 mol / L NaCl and deionized water at a scan rate of 100 mV / s for 1000 cycles. All curves in the figure showed good overlap, indicating that the electrolyte obtained in Example 2... It exhibits good stability when used as a positive electrode electrolyte.

[0060] Figure 5 The value shown is 0.10 mol / L Cyclic stability diagram of a neutral aqueous organic flow battery, wherein the positive electrode electrolyte composition is 5 mL 0.01 mol / L The negative electrode electrolyte consisted of 10 mL of 0.01 mol / L BTMAP-Vi and 1.00 mol / L NaCl solution in deionized water. The battery separator was a DSV membrane. The test conditions were constant current mode with a current density of 40 mA cm⁻¹. -2 The charge / discharge cutoff voltage range is 1.5V to 0.5V. The obtained data is shown in Table 1. This indicates that the battery operates at 40mA / cm. -2 After 100 consecutive charge-discharge cycles at a current density, the battery's coulombic efficiency remained close to 100%, and the battery capacity retained 96.631% of the initial capacity, i.e., a capacity retention rate of 99.966 per cycle. This represents a 0.007% improvement in capacity retention per cycle compared to the previously reported 0.1 mol / L 4-OH-TEMPO / BTMAP-Vi.

[0061]

[0062] BTMAP-Vi is a viologen derivative used as the negative electrode electrolyte in an aqueous organic flow battery, and its structural formula is as follows:

[0063]

[0064] Example 3

[0065] Weigh 0.13 g of 4-OH-DICPO and add it to a beaker. Weigh 3.93 g of methyl-β-cyclodextrin (M-β-CD) and add it to the beaker. Add 5 ml of deionized water and stir until completely dissolved. This will prepare a 0.01 mol / L 4-OH-DICPO coating with 3 times the amount of HP-β-CD. Weigh out another 0.58g of NaCl and add it to the beaker, stirring until completely dissolved to prepare a solution of 0.01mol / L NaCl. An electrolyte consisting of 2.00 mol / L NaCl and deionized water.

[0066] Performance verification

[0067] Figure 6 The image shown is of the product prepared in Example 3 of this invention. Cyclic voltammetry curves of an electrolyte composed of NaCl and deionized water, where the positive electrode electrolyte is... Dissolved in an aqueous solution of sodium chloride with a sodium chloride concentration of 2.00 mol / L, the resulting... The concentration was 0.01 mol / L. A three-electrode system was used, with a 3 mm diameter glassy carbon electrode as the working electrode, a platinum electrode as the counter electrode, and a silver chloride electrode (3.5 M KCl solution, standard electrode potential +0.2046 V) as the reference electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, and 100 mV / s. As shown in the figure, the prepared electrolyte exhibited a pair of reversible redox peaks at different scan rates, demonstrating good reproducibility at different scan rates. This indicates that the electrolyte prepared in Example 3 of this invention... When used as a positive electrode electrolyte, it exhibits good electrochemical reversibility. After conversion, the electrode potential is +0.8551V vs SHE, which is an improvement over the electrode potentials in Examples 1 and 2.

[0068] Figure 7 The image shows the 0.01 mol / L solution prepared in Example 3 of this invention. Cyclic voltammetry was performed on an electrolyte consisting of 2.00 mol / L NaCl and deionized water at a scan rate of 100 mV / s for 1000 consecutive scans. All curves in the figure showed good overlap, indicating that the electrolyte prepared in Example 3... It exhibits good electrochemical stability when used as a positive electrode electrolyte.

[0069] Example 4

[0070] Weigh 0.025 g of 4-OH-DICPO and add it to a beaker. Weigh 0.39 g of γ-cyclodextrin (γ-CD) and add it to the beaker. Add 5 ml of deionized water and stir until 4-OH-DICPO is completely dissolved. This prepares the γ-CD-coated 4-OH-DICPO compound. Weigh out 0.58g of NaCl and add it to the beaker, stirring until completely dissolved. This will prepare the product made from... An electrolyte consisting of NaCl and deionized water.

[0071] Performance verification

[0072] Figure 8 The image shown is of the product prepared in Example 3 of this invention. Cyclic voltammetry curves of an electrolyte composed of NaCl and deionized water, where the positive electrode electrolyte is... The electrolyte was dissolved in an aqueous sodium chloride solution with a sodium chloride concentration of 2.00 mol / L. A three-electrode system was used, with a 3 mm diameter glassy carbon electrode as the working electrode, a platinum electrode as the counter electrode, and a silver chloride electrode (3.5 M KCl solution, standard electrode potential +0.2046 V) as the reference electrode. Scan rates were 10 mV / s, 20 mV / s, 50 mV / s, and 100 mV / s. As shown in the figure, the prepared electrolyte exhibited a pair of reversible redox peaks at different scan rates, demonstrating good reproducibility at different scan rates. This indicates that the electrolyte prepared in Example 4 of this invention... When used as a positive electrode electrolyte, it exhibits good electrochemical reversibility, and the calculated electrode potential is +0.7971V vs SHE.

[0073] In summary, the 4-OH-DiCPO provided by this invention, by introducing two six-membered rings on both sides of the active site of the TEMPO molecule to replace the original four methyl groups, provides better steric protection for the active site of the TEMPO molecule, thereby improving the cycle stability of the flow battery. Furthermore, the molecular size of this compound is significantly larger than that of the TEMPO molecule, reducing the transmembrane permeability of the positive electrode electrolyte and increasing the battery life. The 4-OH-DiCPO compound of this invention has a high electrode potential, which is expected to significantly broaden the operating voltage range of flow batteries.

[0074] Since 4-OH-DiCPO is insoluble in water, this invention also provides a method to improve the water solubility of 4-OH-DiCPO through the coating effect of cyclodextrin. In Example 3 of this application, with the help of HP-β-CD coating, the solubility of 4-OH-DICPO in water can reach above 0.50 M, and the electrode potential is significantly improved when the coated material is used as a positive electrode electrolyte. The experimental method is as follows: 4-OH-DICPO and M-β-CD are quantitatively added to 5 mL of deionized water in a 1:3 ratio. When 0.6325 g of 4-OH-DICPO is added, both DICPO and M-β-CD can be completely dissolved, yielding... Its solubility is above 0.5M.

[0075] The 4-OH-DiCPO compound and its cyclodextrin coating of the present invention can be used as positive electrolytes for non-aqueous or aqueous organic flow batteries, and can be assembled with negative electrolytes to form organic flow batteries. They have broad application prospects in the fields of large-scale energy storage of renewable energy and peak shaving of power grids.

[0076] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Use of a piperidinyloxyl radical derivative in a non-aqueous organic flow battery, characterized in that, The application includes the piperidine oxidative radical derivative as a positive electrode electrolyte; Among them, the piperidine oxidase radical derivative has the following structural formula: 。 2. Use according to claim 1, characterized in that, The method for preparing the piperidine oxidative radical derivative includes: Triacetoneamine, cyclohexanone, and ammonium chloride in a molar ratio of 1:3:6 were added to container A, and dimethyl sulfoxide was added as a solvent to obtain a mixture. The mixture was reacted at 68°C for 24 hours under an inert gas atmosphere. After cooling to room temperature, it was extracted with ethyl acetate, purified by column chromatography, and recrystallized from ethanol to obtain a yellow needle-like solid. The obtained yellow needle-like solid, sodium borohydride, and ethanol were added to container B and reacted at room temperature for three hours. After dilution with deionized water, the mixture was extracted with dichloromethane and dried by rotary evaporation to obtain a white scaly solid. The molar ratio of the yellow needle-like solid to sodium borohydride was 1:

1. The obtained white flaky solid, m-chloroperoxybenzoic acid, and ethanol were added to container C. The mixture was reacted in an ice bath for three hours, washed with sodium carbonate solution, extracted with dichloromethane, and purified by column chromatography to obtain the target product. The molar ratio of the white flaky solid to m-chloroperoxybenzoic acid was 1:

2.

3. A method for improving the aqueous solubility of a piperidine radical oxidation derivative, characterized by, Piperidine oxidase radical derivative, its structural formula is: The method for improving the water solubility of the piperidine oxidative radical derivative includes: Piperidine oxidative radical derivatives and cavity coatings in a molar ratio of 1:1 to 10 were added together to deionized water, and after stirring or ultrasonic treatment, a complex with high water solubility was obtained. The cavity coating is one or more of α-cyclodextrin, α-cyclodextrin derivatives, β-cyclodextrin, β-cyclodextrin derivatives, γ-cyclodextrin, and γ-cyclodextrin derivatives.

4. Use according to claim 1, characterized in that, The negative electrode electrolyte in the non-aqueous organic flow battery is one of N-methylphthalimide, 2,3,6-trimethylquinoxaline, and tetralithium-dinaphthalene-3,4,9,10-tetracarboxylate.

5. The application according to claim 1, characterized in that, The electrolyte in the non-aqueous organic flow battery is LiTFSI or LiPF6.

6. The application according to claim 1, characterized in that, The solvent in the non-aqueous organic flow battery is acetonitrile or propylene carbonate.

7. The application of the composite of claim 3 in aqueous or non-aqueous organic flow batteries.

8. The application according to claim 7, characterized in that, The application includes the composite as a positive electrode electrolyte.

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