Application of hydrogenated ring derivative as negative electrode active material of flow battery
By hydrogenating aromatic compounds to form hydrogenated cyclic derivatives, the problem of poor stability of the negative electrode material of the flow battery in a neutral or acidic environment is solved, and a large negative shift of the potential and the improvement of the flow battery performance is achieved.
Patent Information
- Application Number
- CN202510305921.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-05-23
Smart Images
Figure CN120033284A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of liquid flow battery preparation, and in particular relates to the use of a hydrogenated cyclic derivative as a negative electrode active material for a liquid flow battery. Background Art
[0002] Liquid flow batteries have great potential in the field of renewable energy storage due to their long life, high safety and scalability, but their performance and cost are still subject to the selection of key materials. As the core of determining the energy density and economy of the battery, the negative electrode material must have high redox activity, stability and cost-effectiveness.
[0003] At present, the research on negative electrode materials for flow batteries faces two major bottlenecks: First, although high electronegative materials in traditional alkaline systems (such as phenazine or quinone compounds) have relatively negative redox potentials (such as -0.9V vs. SHE), their synthesis process is complex and costly, and they have poor stability in neutral or acidic environments, which limits their practical applications; second, in alkaline electrolyte systems, the redox potential of positive electrode materials (such as ferrocyanide) is relatively low (+0.37V vs. SHE), resulting in insufficient potential difference between the positive and negative electrodes, which restricts the improvement of the overall voltage and energy density of the battery.
[0004] In order to break through the limitations of alkaline systems, the existing method is to optimize the existing negative electrode materials. For example, introducing electron donor groups into quinoxaline molecules to regulate the redox potential. However, this method has a limited regulation range and is highly dependent on complex molecular design, making it difficult to achieve a large negative shift in potential. In addition, existing research has mostly focused on alkaline systems, and there is insufficient research on the compatibility of neutral or acidic electrolytes, resulting in poor matching between negative electrode materials and high-potential positive electrode materials, further limiting the overall performance improvement of flow batteries. Summary of the invention
[0005] In response to the above problems, the present invention studies the core structure of aromatic compounds (such as quinoxaline or 1,4-benzoquinone) and finds that by precisely regulating the electron distribution through hydrogenation, the hydrogenated cyclic derivatives after hydrogenation can significantly reduce the redox potential in a neutral or acidic system and increase the battery voltage.
[0006] In order to achieve the above object, the present invention can adopt the following technical solutions:
[0007] On the one hand, the present invention provides a negative electrode electrolyte for a liquid flow battery, which includes at least one hydrogenated cyclic derivative, which can be selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or the hydrogenated cyclic derivative can be selected from substituted or unsubstituted 1,4-cyclohexanedione.
[0008] Preferably, when the hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, the substituent groups can be independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
[0009] More preferably, when the above-mentioned hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline, the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline may be one or more of the 5th, 6th, 7th or 8th positions; or when the above-mentioned hydrogenated cyclic derivative is selected from substituted 1,4-cyclohexanedione, the substitution position of the substituted 1,4-cyclohexanedione may be the 3rd and / or 6th positions.
[0010] Preferably, the pH of the negative electrode electrolyte of the above-mentioned liquid flow battery is ≤7.
[0011] Another aspect of the present invention provides a liquid flow battery, which includes the liquid flow battery negative electrode electrolyte of the present invention.
[0012] Preferably, the above-mentioned liquid flow battery further comprises a positive electrode electrolyte, and the positive electrode electrolyte may comprise quinone compounds and / or TEMPO derivatives.
[0013] In another aspect, the present invention provides a use of a hydrogenated cyclic derivative as a negative electrode active material for a liquid flow battery, wherein the hydrogenated cyclic derivative is selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or substituted or unsubstituted 1,4-cyclohexanedione.
[0014] Preferably, when the hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, the substituent groups can be independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
[0015] More preferably, when the above-mentioned hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline, the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline may be one or more of the 5th, 6th, 7th or 8th positions; or when the above-mentioned hydrogenated cyclic derivative is selected from substituted 1,4-cyclohexanedione, the substitution position of the substituted 1,4-cyclohexanedione may be the 3rd and / or 6th positions.
[0016] The beneficial effects of the present invention include:
[0017] (1) When 5,6,7,8-tetrahydroquinoxaline (substituted or unsubstituted) and 1,4-cyclohexanedione (substituted or unsubstituted) are used in the negative electrode electrolyte of liquid flow batteries, they can both show excellent electrochemical properties. For example, the redox potential of 5,6,7,8-tetrahydroquinoxaline (unsubstituted) in neutral electrolyte can be as low as -1.06 V vs. SHE, which has significant advantages over traditional negative electrode materials. For another example, the redox potential of 1,4-cyclohexanedione (unsubstituted) in acidic electrolyte is -0.22 V vs. SHE, which also shows an extremely high negative potential.
[0018] (2) When 5,6,7,8-tetrahydroquinoxaline (substituted or unsubstituted) and 1,4-cyclohexanedione (substituted or unsubstituted) are used in the negative electrode electrolyte of a flow battery and matched with a positive electrode material (such as 4-OH-TEMPO), the theoretical battery voltage of the flow battery based on the material of the present invention can reach 1.88V, and the energy density potential can reach up to 175Wh L -1 , significantly better than the performance of traditional flow batteries.
[0019] (3) 5,6,7,8-Tetrahydroquinoxaline (substituted or unsubstituted) and 1,4-cyclohexanedione (substituted or unsubstituted) have high solubility and good diffusivity in the electrolyte, which can significantly improve the efficiency of their electrochemical reactions. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is the cyclic voltammetry curve of 1,4-benzoquinone in an acidic environment;
[0021] Figure 2 This is the cyclic voltammetry curve of 1,4-cyclohexanedione in an acidic environment;
[0022] Figure 3 This is the cyclic voltammetry curve of quinoxaline in a neutral environment;
[0023] Figure 4 The cyclic voltammetry curve of 5,6,7,8-tetrahydroquinoxaline in a neutral environment;
[0024] Figure 5 This is the cyclic voltammetry curve of 4-OH-TEMPO in a neutral environment;
[0025] Figure 6 This is the charge and discharge test of 1,4-benzoquinone in acidic electrolyte;
[0026] Figure 7 This is the charge and discharge test of 1,4-cyclohexanedione in acidic electrolyte;
[0027] Figure 8 The charge and discharge test results of quinoxaline in neutral electrolyte;
[0028] Fig. 9 This is the charge-discharge test of 5,6,7,8-tetrahydroquinoxaline in a neutral electrolyte solution. Specific Embodiments
[0029] The embodiments are provided to better illustrate the present invention, but the content of the present invention is not limited to the embodiments provided. Therefore, those skilled in the art can make non-essential improvements and adjustments to the implementation manners according to the above-mentioned inventive content, which still fall within the protection scope of the present invention.
[0030] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. Unless having significantly different meanings in the context, the expressions in the singular form include the plural form. As used herein, it should be understood that terms such as "comprising", "having", "including" are intended to indicate the existence of features, numbers, operations, components, parts, elements, materials or combinations thereof. The terms of the present invention are disclosed in the specification, and are not intended to exclude the possibility of the existence or addition of one or more other features, numbers, operations, components, parts, elements, materials or combinations thereof.
[0031] An embodiment of the present invention provides a negative electrolyte solution for a flow battery, which includes at least one hydrogenated cyclic derivative. The hydrogenated cyclic derivative can be selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or the hydrogenated cyclic derivative can be selected from substituted or unsubstituted 1,4-cyclohexanedione.
[0032] It should be noted that the present invention discovers that by taking quinoxaline and 1,4-benzoquinone as model molecules and saturating the π bonds in the molecules by introducing hydrogen atoms, the electron cloud distribution of the molecules can be fundamentally changed, and the redox potential can be reduced (for example, the redox potential of quinoxaline after hydrogenation can be reduced from -0.91 V vs. Ag|AgCl (ca. -0.71 V vs. SHE) to -1.27 V vs. Ag|AgCl (ca. -1.07 V vs. SHE), and the redox potential of 1,4-benzoquinone after hydrogenation can be reduced from +0.39 V vs. Ag|AgCl (ca. +0.59 V vs. SHE) to -0.43 V vs. Ag|AgCl (ca. -0.23 V vs. SHE)). Specifically, in the unhydrogenated state, the π electron delocalization effect of aromatic molecules will form a high electron density attraction center, restricting the stability of the molecules in the reduced state, thus resulting in a relatively high redox potential; through selective hydrogenation, the π electron delocalization effect is significantly weakened, and the stability of the molecules in the reduced state is improved, thereby achieving a negative shift of the redox potential. In addition, this method is more direct and efficient than peripheral group modification, and at the same time avoids the problems of stability and solubility caused by complex structures in traditional designs.
[0033] It should also be noted that the derivatives of 5,6,7,8-tetrahydroquinoxaline and 1,4-cyclohexanedione based on the hydrogenation of quinoxaline and 1,4-benzoquinone (i.e., 5,6,7,8-tetrahydroquinoxaline substituted with different substituents and 1,4-cyclohexanedione substituted with different substituents) also have lower redox potentials.
[0034] It should also be noted that the negative electrode electrolyte of the liquid flow battery in the present invention includes at least one hydrogenated cyclic derivative, which means that the negative electrode electrolyte of the liquid flow battery can include 5,6,7,8-tetrahydroquinoxaline or 1,4-cyclohexanedione alone, or can include 5,6,7,8-tetrahydroquinoxaline and 1,4-cyclohexanedione at the same time; it can also include one of the derivatives of 5,6,7,8-tetrahydroquinoxaline or 1,4-cyclohexanedione substituted by a substituent alone, or can include two or more of the derivatives of 5,6,7,8-tetrahydroquinoxaline or 1,4-cyclohexanedione substituted by a substituent at the same time.
[0035] In some specific examples, when the hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, the substituent groups can be independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
[0036] It should be noted that, as described above, 5,6,7,8-tetrahydroquinoxaline substituted with different substituents and 1,4-cyclohexanedione substituted with different substituents have lower redox potentials than 5,6,7,8-tetrahydroquinoxaline and 1,4-cyclohexanedione, wherein the type of the substituent may be any one of alkyl, amino, halogen, hydroxyl or nitro; in addition, “respectively independently selected from” means that the substituent of 5,6,7,8-tetrahydroquinoxaline may be any one of alkyl, amino, halogen, hydroxyl or nitro; the substituent of 1,4-cyclohexanedione may also be any one of alkyl, amino, halogen, hydroxyl or nitro.
[0037] In some specific examples, when the above-mentioned hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline, the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline can be one or more of the 5th, 6th, 7th or 8th positions; or when the above-mentioned hydrogenated cyclic derivative is selected from substituted 1,4-cyclohexanedione, the substitution position of the substituted 1,4-cyclohexanedione can be the 3rd and / or 6th positions.
[0038] It should be noted that the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline in the present invention can be one or more of the 5th, 6th, 7th or 8th positions; the substitution position of the substituted 1,4-cyclohexanedione can be the 3rd and / or 6th position; in addition, when there are multiple substitution positions, the types of substituents can be the same or different.
[0039] In some specific examples, the pH of the negative electrode electrolyte of the above-mentioned liquid flow battery is ≤7.
[0040] It should be noted that when 5,6,7,8-tetrahydroquinoxaline (substituted or unsubstituted) or 1,4-cyclohexanedione (substituted or unsubstituted) is used in the negative electrode of a flow battery, it still has a low redox potential in a neutral or acidic electrolyte system.
[0041] An embodiment of the present invention further provides a liquid flow battery, which includes the liquid flow battery negative electrode electrolyte of the present invention.
[0042] It should be noted that the negative electrode electrolyte of the flow battery containing 5,6,7,8-tetrahydroquinoxaline (substituted or unsubstituted) and 1,4-cyclohexanedione (substituted or unsubstituted) can be prepared into a flow battery; of course, it should be understood that the flow battery also includes other structures known in the art, such as positive electrode electrolyte, battery separator, battery stack, electrolyte circulation system, battery management system, power conversion system and thermal management system, etc.
[0043] In some specific examples, the liquid flow battery further includes a positive electrode electrolyte, and the positive electrode electrolyte may include quinone compounds and / or TEMPO derivatives.
[0044] It should be noted that the negative electrode electrolyte of the flow battery constructed by the present invention has a low redox potential, so it is preferably matched with high-potential positive electrode molecules (such as quinones and TEMPO derivatives, such as 4-OH-TEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical)), so as to achieve the optimized design of high-voltage flow batteries under a wider range of operating conditions. For example, after the negative electrode electrolyte (5,6,7,8-tetrahydroquinoxaline) of the flow battery in the present invention is matched with the positive electrode material (such as 4-OH-TEMPO), the theoretical battery voltage of the flow battery based on the material of the present invention can reach 1.88V, and the energy density potential is as high as 175Wh L -1 , significantly better than the performance of traditional flow batteries.
[0045] The embodiment of the present invention also provides a use of a hydrogenated cyclic derivative as a negative electrode active material for a liquid flow battery. The hydrogenated cyclic derivative can be selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or the hydrogenated cyclic derivative can be selected from substituted or unsubstituted 1,4-cyclohexanedione.
[0046] It should be noted that, as mentioned above, both 5,6,7,8-tetrahydroquinoxaline (substituted or unsubstituted) and 1,4-cyclohexanedione (substituted or unsubstituted) can reduce the redox potential, so they can be used as active materials for the negative electrode electrolyte of liquid flow batteries.
[0047] In some specific examples, when the hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, the substituent groups can be independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
[0048] In some specific examples, when the above-mentioned hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline, the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline can be one or more of the 5-position, 6-position, 7-position or 8-position; or when the above-mentioned hydrogenated cyclic derivative can be selected from substituted 1,4-cyclohexanedione, the substitution position of the substituted 1,4-cyclohexanedione can be the 3-position and / or the 6-position.
[0049] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific examples, but the content of the present invention is not limited to the following examples.
[0051] 1. Cyclic voltammetry test of different negative electrode active materials
[0052] Example 11 Cyclic voltammetry test of 4-benzoquinone and 1,4-cyclohexanedione in acidic electrolyte
[0053] This example aims to test the redox behavior of 1,4-benzoquinone and its hydrogenated derivative 1,4-cyclohexanedione in an acidic electrolyte; specifically, 10 ml of electrolyte was prepared (the electrolyte contained 1 M NaCl and 10 mM active substances, and the pH was adjusted to 2 by HCl), the experiment was carried out at a constant temperature of 25 ° C, and a cyclic voltammetry test was performed using a classic three-electrode system (the working electrode was a glassy carbon electrode, the reference electrode was an Ag|AgCl electrode, and the counter electrode was a platinum electrode); the active substances were 1,4-benzoquinone and 1,4-cyclohexanedione, respectively, and the constructed electrolytes were tested separately.
[0054] The cyclic voltammetry curve shows that 1,4-benzoquinone exhibits a pair of clear redox peaks in the two-electron transfer reaction, which corresponds to the conversion between 1,4-benzoquinone and 1,4-hydroquinone. This behavior has good electrochemical reversibility ( Figure 1 ); In contrast, 1,4-cyclohexanedione exhibits two pairs of distinct redox peaks, corresponding to its stepwise single electron transfer steps, indicating its characteristic reaction pathway after hydrogenation ( Figure 2 ); and, the redox potential shows that the redox potential of 1,4-benzoquinone is +0.39 Vvs.Ag|AgCl (ca.+0.59 Vvs.SHE), while the redox potential of 1,4-cyclohexanedione can be significantly reduced to -0.43 Vvs.Ag|AgCl (ca.-0.23 Vvs.SHE).
[0055] From the above, we can see that the cyclic voltammetry curves of 1,4-benzoquinone and 1,4-cyclohexanedione are symmetrical, and the peak potential difference is small, which further proves their excellent electrochemical reversibility; the above results show that the molecular hydrogenation strategy can effectively reduce the redox potential of 1,4-benzoquinone while maintaining its good electrochemical properties.
[0056] Example 2 Cyclic Voltammetry of Quinoxaline and 5,6,7,8-Tetrahydroquinoxaline in Neutral Electrolyte
[0057] The present embodiment aims to test the redox behavior of quinoxaline and its hydrogenated derivative 5,6,7,8-tetrahydroquinoxaline in a neutral electrolyte; specifically, 10 ml of electrolyte was prepared (the electrolyte contained 1 M NaCl and 50 mM active substances), the experiment was carried out at a constant temperature of 25 ° C, and a cyclic voltammetry test was performed using a classic three-electrode system (the working electrode was a glassy carbon electrode, the reference electrode was an Ag|AgCl electrode, and the counter electrode was a platinum electrode); the active substances were quinoxaline and 5,6,7,8-tetrahydroquinoxaline, respectively, and the constructed electrolytes were tested separately.
[0058] The cyclic voltammetry curve shows that quinoxaline exhibits a redox potential of -0.91 V vs. Ag|AgCl (ca.–0.71 V vs. SHE) in the cyclic voltammetry test, and has a pair of clear redox peaks, showing good electrochemical reversibility ( Figure 3 ); and 5,6,7,8-tetrahydroquinoxaline as a hydrogenated derivative, its redox potential is further reduced to -1.27 V vs. Ag|AgCl (ca.–1.07 V vs. SHE) ( Figure 4 ), and also exhibited good electrochemical stability; the above results indicate that the molecular hydrogenation strategy can effectively reduce the redox potential of quinoxaline while maintaining its good electrochemical properties.
[0059] Comparative Example 1
[0060] This control example is intended to test the redox behavior of 4-OH-TEMPO in a neutral electrolyte; specifically, 10 ml of electrolyte was prepared (the electrolyte contained 1 M NaCl and 50 mM 4-OH-TEMPO), the experiment was carried out at a constant temperature of 25 ° C, and a classic three-electrode system (the working electrode was a glassy carbon electrode, the reference electrode was an Ag|AgCl electrode, and the counter electrode was a platinum electrode) was used for cyclic voltammetry testing.
[0061] The cyclic voltammetry curve shows that 4-OH-TEMPO exhibits a redox potential of +0.61Vvs.Ag / AgCl in the cyclic voltammetry test and has a pair of clear redox peaks, showing good electrochemical reversibility ( Figure 5 ).
[0062] In addition, it can be seen from Example 2 and Comparative Example 1 that after 5,6,7,8-tetrahydroquinoxaline is matched with a cathode material (such as 4-OH-TEMPO), the theoretical battery voltage of the flow battery based on the material of the present invention can reach 1.88V, and the energy density potential is as high as 175WhL -1 , significantly better than the performance of traditional flow batteries; the specific calculation is as follows:
[0063] The theoretical capacity (Cap) of the electrolyte is calculated as follows:
[0064] Capacity(C ap )=nCF / 3600=nC×26.8(Ah / L);
[0065] Wherein, the theoretical capacity (Cap) of the electrolyte refers to the amount of charge stored in a unit volume of electrolyte, n represents the number of electrons transferred in the redox reaction, C represents the concentration of the redox electrolyte (M), and F represents the Faraday constant.
[0066] Theoretical energy density E d The calculation of is as follows:
[0067] Energy Density(E d )=C ap V(Wh / L);
[0068] In the formula, C ap Represents the lower theoretical capacity of the positive and negative electrolytes, and V represents the battery voltage (V).
[0069] 2. Charge and discharge test of different negative electrode active materials
[0070] Example 31. Charge and discharge test of 4-benzoquinone and 1,4-cyclohexanedione in acidic electrolyte
[0071] In this embodiment, the charge and discharge performance of 1,4-benzoquinone and 1,4-cyclohexanedione in acidic electrolyte is evaluated respectively; specifically, 10 ml of negative electrode electrolyte (the negative electrode electrolyte contains 1 M NaCl and 10 mM active material, and HCl is used to adjust the pH to 2) and 10 ml of positive electrode electrolyte (the positive electrode electrolyte contains 1 M NaCl, and the pH is adjusted to 2) are prepared respectively; wherein the active materials are 1,4-benzoquinone and 1,4-cyclohexanedione respectively; Nafion 212 membrane is used to separate the positive and negative electrolytes; the charge and discharge performance is tested by constant current cyclic charge and discharge test method, the test is carried out at 25 ° C, and the charge and discharge current density of the test is 20 mA cm -2 .
[0072] Test results such as Figure 6 and Figure 7As shown, the results show that the charge and discharge voltages are consistent with the cyclic voltammetry test results. In the first charge and discharge cycle, the charge voltage of 1,4-benzoquinone is +0.47V vs.Ag / AgCl, and the discharge voltage is +0.34V vs.Ag / AgCl; the charge voltage of 1,4-cyclohexanedione is -0.42V vs.Ag / AgCl, and the discharge voltage is -0.36V vs.Ag / AgCl.
[0073] The charge and discharge curves of the two materials show extremely small overpotentials, demonstrating their excellent electrochemical performance. In addition, the significant reduction in the potential of 1,4-cyclohexanedione provides a technical possibility for increasing the overall voltage of liquid flow batteries, further broadening the range of negative electrode material choices for acidic systems.
[0074] Example 4 Charge and discharge test of quinoxaline and 5,6,7,8-tetrahydroquinoxaline in neutral electrolyte
[0075] This example evaluates the charge and discharge performance of quinoxaline and its hydrogenated derivative 5,6,7,8-tetrahydroquinoxaline in a neutral electrolyte; specifically, 10 ml of negative electrode electrolyte (the negative electrode electrolyte contains 1 M NaCl and 10 mM active material) and 10 ml of positive electrode electrolyte (the positive electrode electrolyte contains 1 M NaCl) are prepared respectively; the active materials are quinoxaline and 5,6,7,8-tetrahydroquinoxaline, respectively; a Nafion 212 membrane is used to separate the positive and negative electrolytes; the charge and discharge performance is tested by a constant current cyclic charge and discharge test method, the test is carried out at 25°C, and the charge and discharge current density of the test is 20 mA cm -2 .
[0076] The test results are as follows Figure 8 and Fig. 9 As shown, the experimental results show that the charge and discharge voltages are consistent with the cyclic voltammetry test results. In the first charge and discharge cycle, the charge voltage of quinoxaline is -0.93V vs.Ag / AgCl, and the discharge voltage is -0.89V vs.Ag / AgCl; the charge voltage of 5,6,7,8-tetrahydroquinoxaline is -1.19V vs.Ag / AgCl, and the discharge voltage is -1.17V vs.Ag / AgCl.
[0077] The charge-discharge curves of the two materials show extremely small overpotentials, indicating good cycle stability. The above results show that 5,6,7,8-tetrahydroquinoxaline can achieve significant potential reduction through the hydrogenation strategy.
[0078] 3. Other Redox Potential Tests of 1,4-Benzoquinone
[0079] Comparative Example 1
[0080] The redox potential of the prepared electrolyte was tested using the other 1,4-benzoquinone derivatives in Table 1 below according to the test method of Example 1. The test results are shown in Table 1 below.
[0081] Table 1 Redox potentials of 1,4-benzoquinone substituted with different substituents
[0082]
[0083] It can be seen from Table 1 above that the redox potentials of 1,4-benzoquinone substituted with different substituents are higher than that of 1,4-cyclohexanedione, indicating that the effect of 1,4-cyclohexanedione obtained by hydrogenation is better than that of 1,4-benzoquinone derivatives substituted with other substituents.
[0084] IV. Redox Potential Test of Other Quinoxaline Derivatives
[0085] The redox potential of the electrolyte prepared by testing other quinoxaline derivatives in Table 2 below according to the testing method of Example 2 is shown in Table 2 below.
[0086] Table 2 Redox potentials of quinoxaline substituted with different substituents
[0087]
[0088] It can be seen from Table 2 above that the redox potentials of quinoxaline substituted with different substituents are higher than that of 5,6,7,8-tetrahydroquinoxaline, indicating that the effect of 5,6,7,8-tetrahydroquinoxaline obtained by hydrogenation is better than that of quinoxaline derivatives substituted with other substituents.
[0089] It should be pointed out that the above embodiments are only intended to illustrate the technical solution of the present invention, and are not intended to limit it. Although the present invention has been described in detail through the preferred embodiments, those skilled in the art should recognize that, without departing from the core principle and protection scope of the technical solution of the present invention, the technical solution of the present invention can be appropriately changed or replaced by equivalents, and these changes or replacements should be deemed to be within the protection scope of the claims of the present invention.
Claims
1. A negative electrode electrolyte for a liquid flow battery, characterized in that: The invention comprises at least one hydrogenated cyclic derivative, wherein the hydrogenated cyclic derivative is selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or the hydrogenated cyclic derivative is selected from substituted or unsubstituted 1,4-cyclohexanedione.
2. The negative electrode electrolyte of the flow battery according to claim 1, characterized in that: The hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, and the substituent groups are each independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
3. According to the negative electrode electrolyte of the liquid flow battery according to claim 2, the substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline is one or more of the 5th, 6th, 7th or 8th positions; or the substitution position of the substituted 1,4-cyclohexanedione is the 3rd and / or 6th positions.
4. The negative electrode electrolyte of a flow battery according to any one of claims 1 to 3, characterized in that: The pH of the negative electrode electrolyte of the flow battery is ≤7.
5. A liquid flow battery, characterized in that: A negative electrode electrolyte for a liquid flow battery comprising any one of claims 1 to 4.
6. The liquid flow battery according to claim 5, characterized in that: The liquid flow battery also includes a positive electrode electrolyte, which includes a quinone compound and / or a TEMPO derivative.
7. Use of a hydrogenated cyclic derivative as a negative electrode active material for a liquid flow battery, wherein the hydrogenated cyclic derivative is selected from substituted or unsubstituted 5,6,7,8-tetrahydroquinoxaline; or the hydrogenated cyclic derivative is selected from substituted or unsubstituted 1,4-cyclohexanedione.
8. The use according to claim 7, characterized in that: The hydrogenated cyclic derivative is selected from substituted 5,6,7,8-tetrahydroquinoxaline or substituted 1,4-cyclohexanedione, and the substituent groups are each independently selected from any one of alkyl, amino, halogen, hydroxyl or nitro.
9. The use according to claim 8, characterized in that: The substitution position of the substituted 5,6,7,8-tetrahydroquinoxaline is one or more of the 5th, 6th, 7th or 8th position; or the substitution position of the substituted 1,4-cyclohexanedione is the 3rd and / or 6th position.
10. The use according to any one of claims 7 to 9, characterized in that The pH of the negative electrode electrolyte of the flow battery is ≤7.