A bio-based flow battery electrolyte material and preparation method thereof

Abstract

This invention discloses a bio-based flow battery electrolyte material and its preparation method, belonging to the field of battery energy storage technology. The invention involves the catalytic oxidation and degradation of lignin using heteropolyacids, followed by extraction and purification of vanillin from the lignin, and then deformylation with hydrogen peroxide in an alkaline environment to obtain 2-methoxyhydroquinone. 2-Methoxyhydroquinone, a quinone compound, can achieve energy storage through redox reactions between quinone and hydroquinone, thus improving electrochemical activity. Using 2-methoxyhydroquinone as the negative electrode electrolyte material in an aqueous flow battery offers advantages over traditional metal electrolytes: abundant sources, environmental friendliness, high capacity, avoidance of metal ion cross-linking, and long service life, making it suitable for large-scale energy storage technologies.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery energy storage, and in particular relates to a bio-based liquid flow battery electrolyte material and a preparation method thereof. Background Art

[0002] Renewable energy is an effective way to solve problems such as energy depletion and environmental pollution. Clean renewable energy includes wind energy, solar energy, hydropower, geothermal energy, ocean energy and bioenergy. However, renewable energy such as solar energy, wind energy and hydropower depends on natural conditions and has defects such as intermittent, volatile and uncontrollable. With the rapid development of renewable energy, energy storage technology has gradually become an important link in the efficient utilization of energy. At present, the developed energy storage technology can be divided into physical energy storage and chemical energy storage according to the different energy storage media. Physical energy storage includes pumped storage, compressed air energy storage, flywheel energy storage, superconducting energy storage and supercapacitor energy storage. Among them, pumped storage, compressed air energy storage and flywheel energy storage are mechanical energy storage methods, which have specific requirements for sites and equipment. The production cost of superconducting energy storage and supercapacitor energy storage is relatively high. Chemical energy storage includes fuel cells, lead-acid batteries, lead-carbon batteries, lithium-ion batteries, sodium-sulfur batteries and flow batteries. Chemical energy storage is not restricted by the geographical environment, has high energy storage efficiency, capacity and power, and low cost, and has a wide range of applications. Among them, flow batteries have the advantages of easy regulation of storage capacity, long cycle life, high operational safety and easy maintenance, which make them the first choice for large-scale energy storage technology.

[0003] With the continuous development of chemical energy storage technology, organic compounds represented by quinones and their derivatives are a potential electrolyte material for liquid flow batteries due to their wide sources and low cost. However, the reserves of natural quinone compounds in nature are relatively small, while the most abundant lignin on earth contains a large number of phenol structures, which are expected to be used as electrolytes for liquid flow batteries and achieve large-scale application through redox conversion to quinone structures.

[0004] Since lignin has a complex and strong three-dimensional network structure, in order to utilize the phenolic hydroxyl groups of lignin to achieve energy storage, lignin needs to be depolymerized. Thermal cracking, hydrogenation reduction depolymerization, oxidative depolymerization and other methods have been widely used in the depolymerization of lignin. Polyoxometalates, also known as heteropolyacids (POM), are highly efficient and recyclable catalysts that have been used to remove residual lignin from unbleached pulp fibers or directly depolymerize lignin into high-value-added chemicals. Summary of the invention

[0005] In view of the above problems existing in the prior art, the technical problem to be solved by the present invention is to provide a bio-based liquid flow battery electrolyte material, which is used as a negative electrode electrolyte material of an alkaline aqueous liquid flow battery; another technical problem to be solved by the present invention is to provide a method for preparing the bio-based liquid flow battery electrolyte material.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a bio-based liquid flow battery electrolyte material comprises the following steps: extracting small molecular weight lignin from wood powder by heteropolyacid catalytic oxidation, and then obtaining vanillin by extraction and purification; in an alkaline environment, treating the vanillin with hydrogen peroxide for deformylation to obtain 2-methoxyhydroquinone, and using 2-methoxyhydroquinone as a negative electrode electrolyte material for an aqueous liquid flow battery.

[0008] The specific steps include:

[0009] 1) adding wood powder, heteropoly acid and methanol / water mixture into a high temperature and high pressure reactor according to the usage ratio, introducing oxygen into the reactor to remove the air in the reactor, and then extracting the reaction liquid containing small molecular weight lignin through heteropoly acid catalytic oxidation reaction;

[0010] 2) evaporating and concentrating the reaction solution containing small molecular weight lignin to remove methanol in the reaction solution, and extracting with dichloromethane and separating with a chromatography column filled with G10-dextran to obtain vanillin;

[0011] 3) Weigh vanillin and place it in a reaction bottle, and add NaOH aqueous solution and hydrogen peroxide to react at room temperature. After the reaction is completed, add hydrochloric acid to quench and terminate the reaction; extract the reaction solution with ethyl acetate and remove moisture in the organic phase with anhydrous sodium sulfate, and obtain 2-methoxyhydroquinone after vacuum drying;

[0012] 4) 2-Methoxyhydroquinone is used as negative electrode electrolyte material for aqueous liquid flow batteries.

[0013] Furthermore, in step 1), the usage ratio of wood powder, heteropoly acid and methanol / water mixture is 1.0 g:1.8 g:40 mL.

[0014] Furthermore, in step 1), the heteropoly acid is phosphomolybdic acid; and the volume ratio of methanol to water in the methanol / water mixture is 9:1.

[0015] Furthermore, in step 1), the heteropolyacid catalytic oxidation reaction temperature is 130-190° C., and the heteropolyacid catalytic oxidation reaction time is 1-4 h.

[0016] Furthermore, in step 1), after oxygen is introduced into the reactor to remove the air in the reactor, 10.0 bar of oxygen is filled in, the speed is set to 500 rpm, and the reaction liquid containing small molecular weight lignin is extracted through heteropolyacid catalytic oxidation reaction. The heteropolyacid catalytic oxidation reaction temperature is 150°C and the heteropolyacid catalytic oxidation reaction time is 2 hours.

[0017] Furthermore, in step 2), the reaction solution containing small molecular weight lignin is evaporated and concentrated to remove methanol in the reaction solution, and the organic phase product is extracted by dichloromethane, and then the vanillin with a molecular weight of 200-500 is separated by a chromatography column filled with G10-dextran filler.

[0018] The chromatography column filled with G10-dextran had a length of 100.0 cm and a diameter of 1.0 cm.

[0019] Furthermore, in step 3), the usage ratio of vanillin, NaOH aqueous solution, hydrogen peroxide and hydrochloric acid is 0.1 g: 20 mL: 2 mL: 5 mL.

[0020] Furthermore, in step 3), the concentration of the NaOH aqueous solution is 1 mol / L, the mass percentage of the hydrogen peroxide is 30%, and the concentration of the hydrochloric acid is 2 mol / L.

[0021] The bio-based liquid flow battery electrolyte material prepared by the above method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention uses heteropolyacid to catalyze the oxidation and degradation of lignin, which can achieve selective catalytic oxidation and increase the yield of vanillin;

[0024] (2) The present invention deformylates vanillin to obtain 2-methoxyhydroquinone, which can achieve energy storage through the redox reaction between quinone and hydroquinone, thereby improving its electrochemical activity;

[0025] (3) The present invention uses 2-methoxyhydroquinone as an aqueous liquid flow battery electrolyte material, which has high capacitance, high energy density and long service life, and can be widely used in large-scale energy storage technology;

[0026] (4) Compared with traditional metal electrolytes, the bio-based liquid flow battery electrolyte material of the present invention is abundant in source, environmentally friendly, and avoids the cross-talk of metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the two-dimensional NMR spectrum of lignin after heteropolyacid catalytic oxidation in Example 1;

[0028] Figure 2 is the mass spectrum of 2-methoxyhydroquinone prepared in Example 1;

[0029] Figure 3 The constant voltage charge-discharge curve and constant current charge-discharge curve are shown when the 2-methoxyhydroquinone prepared in Example 1 is used as the negative electrode electrolyte material of the aqueous liquid flow battery. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments. These embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and substance of the present invention, the modification or replacement of the inventive method, step or condition, all belong to the scope of the present invention. In the following examples, if there is no special explanation, the technical means used in the examples are conventional means well known to those skilled in the art.

[0031] Example 1

[0032] 1.0 g of eucalyptus powder, 1.8 g of phosphomolybdic acid and 40 mL of methanol / water mixture (volume ratio 9:1) were placed in a 100 mL high temperature and high pressure reactor (KZF, China). After oxygen was introduced into the reactor to remove the air in the reactor, 10.0 bar of oxygen was filled, the speed was set to 500 rpm, the reaction temperature was 150 ° C, and the reaction time was 2 h. After the reaction was completed, the reactor was quickly cooled to room temperature in an ice water bath. The reaction mixture was filtered through qualitative filter paper and washed three times with deionized water. The methanol in the reaction solution was removed by evaporation and concentration, and the organic phase product was extracted with dichloromethane, and then the product with a molecular weight of 200-500 was separated by a chromatography column (length 100.0 cm, diameter 1.0 cm) filled with G10-dextran filler. The yield of vanillin was 16.4%.

[0033] Weigh 0.1g of vanillin into a 100mL reaction bottle, add 20mL of NaOH aqueous solution (1M) and 2mL of hydrogen peroxide, react at room temperature for 20min, and after the reaction is completed, add 5mL of hydrochloric acid (2M) to quench and terminate the reaction. The reaction solution is extracted with ethyl acetate and the water in the organic phase is removed with anhydrous sodium sulfate. After vacuum drying, 2-methoxyhydroquinone is obtained. The yield of 2-methoxyhydroquinone is 76.6%.

[0034] Attached Figure 1 The two-dimensional NMR spectrum of lignin after heteropolyacid-catalyzed oxidation reaction shows that the connecting bonds of lignin are destroyed and lignin is effectively degraded.

[0035] Attached Figure 2 It shows the GC-MS spectrum of 2-methoxyhydroquinone after deformylation.

[0036] The cyclic voltammetry curve was tested using a CHI 660e electrochemical workstation (660e, China). A certain amount of 2-methoxyhydroquinone was weighed and dissolved in 40 mL of KOH aqueous solution (pH = 13) to prepare a saturated electrolyte, which was placed in an electrolytic cell and passed through nitrogen for 20 minutes to avoid the influence of oxygen on the redox reaction. The electrolyte was subjected to a cyclic voltammetry test using a three-electrode system to determine the redox potential of 2-methoxyhydroquinone. The oxidation potential was measured to be 0.535 V vs. SHE, and the reduction potential was -0.415 V vs. SHE.

[0037] For the cyclic charge and discharge test of the full battery, the electrolyte was assembled in a fully discharged state. Positive electrolyte: 0.683g K4Fe(CN)6 was weighed and dissolved in 40mL KOH aqueous solution (1mol / L) to prepare 0.04mol / L K4Fe(CN)6 positive electrolyte; Negative electrolyte: 0.056g 2-methoxyhydroquinone was dissolved in 40mL KOH aqueous solution (1mol / L) to prepare 0.01mol / L lignin anthraquinone negative electrolyte. Serpertine flow-type pyro-sealed POCO graphite flow plates were used as collector electrodes on both sides of the flow battery, Nafion-212 membrane was used as ion exchange membrane, and polytetrafluoroethylene sheets were used to seal between the graphite plates. The electrolyte was controlled by a peristaltic pump at a rate of 50mL / min. Constant current charge and discharge tests and constant voltage charge and discharge tests were performed using a CHI 660e electrochemical workstation (660e, China).

[0038] Attached Figure 3 The constant voltage charge and discharge curve and the constant current charge and discharge curve of Example 1 are shown. The open circuit voltage of the battery can reach 1.0V, and the capacity is 108.0mAh·L -1 , energy density is 17.0Wh·L -1 , after 200 cycles of charge and discharge, it can still retain 87.4% of the specific capacitance.

[0039] Example 2

[0040] 1.0 g of eucalyptus powder, 1.8 g of phosphomolybdic acid and 40 mL of methanol / water mixture (volume ratio 9:1) were placed in a 100 mL high temperature and high pressure reactor (KZF, China). After oxygen was introduced into the reactor to remove the air in the reactor, 10.0 bar of oxygen was filled, the speed was set to 500 rpm, the reaction temperature was 130 ° C, and the reaction time was 1 h. After the reaction was completed, the reactor was quickly cooled to room temperature in an ice water bath. The reaction mixture was filtered through qualitative filter paper and washed three times with deionized water. The methanol in the reaction solution was removed by evaporation and concentration, and the organic phase product was extracted by dichloromethane, and then the product with a molecular weight of 200-500 was separated by a chromatography column (length 100.0 cm, diameter 1.0 cm) filled with G10-dextran filler. The yield of vanillin was 10.2%.

[0041] Weigh 0.1g of vanillin into a 100mL reaction bottle, add 20mL of NaOH aqueous solution (1M) and 2mL of hydrogen peroxide, react at room temperature for 10min, and after the reaction is completed, add 5mL of hydrochloric acid (2M) to quench and terminate the reaction. The reaction solution is extracted with ethyl acetate and the water in the organic phase is removed with anhydrous sodium sulfate. After vacuum drying, 2-methoxyhydroquinone is obtained. The yield of 2-methoxyhydroquinone is 69.5%.

[0042] The cyclic voltammetry test and the cyclic charge-discharge test are the same as those in Example 1.

Claims

1. A method for preparing a bio-based flow battery electrolyte material, characterized in that: The following steps are involved: The small molecular weight lignin is extracted from wood powder by heteropolyacid catalytic oxidation, and then vanillin is obtained by extraction and purification; under an alkaline environment, the vanillin is deformylated by hydrogen peroxide to obtain 2-methoxyhydroquinone, and the 2-methoxyhydroquinone is used as the negative electrode electrolyte material of the aqueous liquid flow battery; specifically, the following steps are included: 1) adding wood powder, heteropoly acid and methanol / water mixture into a high temperature and high pressure reactor according to the dosage ratio, introducing oxygen into the reactor to remove the air in the reactor, and then extracting the reaction liquid containing small molecular weight lignin through heteropoly acid catalytic oxidation reaction; 2) The reaction solution containing small molecular weight lignin is evaporated and concentrated to remove methanol in the reaction solution, and vanillin is obtained by extraction with dichloromethane and separation with a chromatography column filled with G10-dextran; 3) Weigh vanillin and place it in a reaction bottle, add NaOH aqueous solution and hydrogen peroxide, react at room temperature, and after the reaction is completed, add hydrochloric acid to quench and terminate the reaction; extract the reaction solution with ethyl acetate and remove moisture in the organic phase with anhydrous sodium sulfate, and obtain 2-methoxyhydroquinone after vacuum drying; 4) Using 2-methoxyhydroquinone as negative electrode electrolyte material for aqueous liquid flow batteries; Wherein, in step 1), the amount ratio of wood powder, heteropoly acid and methanol / water mixture is 1.0g:1.8g:40mL; the heteropoly acid catalytic oxidation reaction temperature is 130-190°C, and the heteropoly acid catalytic oxidation reaction time is 1-4h; the heteropoly acid is phosphomolybdic acid; In step 3), the usage ratio of vanillin, NaOH aqueous solution, hydrogen peroxide and hydrochloric acid is 0.1 g: 20 mL: 2 mL: 5 mL.

2. The method for preparing a bio-based flow battery electrolyte material according to claim 1, characterized in that: In step 1), the volume ratio of methanol to water in the methanol / water mixture is 9:

1.

3. The method for preparing a bio-based flow battery electrolyte material according to claim 1, characterized in that: In step 1), the heteropolyacid catalytic oxidation reaction temperature is 150° C., and the heteropolyacid catalytic oxidation reaction time is 2 h.

4. The method for preparing a bio-based flow battery electrolyte material according to claim 1, characterized in that: In step 2), the reaction solution containing small molecular weight lignin is evaporated and concentrated to remove methanol in the reaction solution, and the organic phase product is extracted by dichloromethane, and then the vanillin with a molecular weight of 200-500 is separated by a chromatography column filled with G10-dextran filler.

5. The method for preparing a bio-based flow battery electrolyte material according to claim 1, characterized in that: In step 3), the concentration of the NaOH aqueous solution is 1 mol / L, the mass percentage of the hydrogen peroxide is 30%, and the concentration of the hydrochloric acid is 2 mol / L.

6. The bio-based liquid flow battery electrolyte material prepared by the method according to any one of claims 1 to 5.

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