Liquid flow battery diaphragm material, activation method thereof, and liquid flow battery

Abstract

The present invention relates to the field of flow battery diaphragm technology, disclosing a flow battery diaphragm material, an activation method thereof, and a flow battery. The activation method comprises contacting the flow battery diaphragm material with an acid solution at room temperature in the presence of ultrasound for activation. This activation method, performed at room temperature, avoids the drawbacks of using hot sulfuric acid and effectively improves the performance of the flow battery diaphragm material.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid flow battery diaphragms, and in particular to a liquid flow battery diaphragm material, an activation method thereof, and a liquid flow battery. Background Art

[0002] Flow batteries are a type of electrochemical energy storage technology that generally utilizes the changes in the valence state of active substances in the liquid phases of the positive and negative electrodes during charge and discharge to store and release energy. Currently successfully developed technologies include all-vanadium flow batteries, iron-chromium flow batteries, and zinc-bromine flow batteries. Flow batteries are primarily suitable for large-scale energy storage applications, including renewable energy grid integration, power plant peak regulation, smart microgrids, uninterruptible power supplies, and standalone power supplies. Due to the rapid development of the new energy industry and the energy-saving and environmental protection industries, demand for large-scale energy storage technologies such as flow batteries is rapidly increasing.

[0003] Diaphragm material is the core component of liquid flow battery. Processing the diaphragm material of liquid flow battery can effectively improve the electrochemical properties of the diaphragm material, thereby increasing the output power of the liquid flow battery.

[0004] In 2016, Xi Jingyu et al. published an article titled "Insights into the Impact of the Nafion Membrane Pretreatment Process on Vanadium Flow Battery Performance" in the journal Applied Materials & Interfaces. The article compared and analyzed the performance of membrane materials treated under different conditions in liquid flow batteries and found that the performance of the membrane material was optimal when the membrane was treated with boiling hot sulfuric acid.

[0005] In a 2016 article published in the Journal of Membrane Science, Rafael Kuwertz et al., titled "Influence of acid pretreatment on ionic conductivity of nafion membranes," analyzed the performance of acid-treated membrane materials under different conditions and found that higher temperatures led to higher membrane moisture content. Acid concentration and acid type had less influence on membrane conductivity than temperature.

[0006] Existing methods for activating membrane materials primarily rely on hot sulfuric acid treatment. This method consumes a lot of energy and, due to the use of highly concentrated sulfuric acid, the highly acidic and corrosive nature of the sulfuric acid increases the requirements for membrane treatment vessels, equipment, and materials, leading to higher costs.

[0007] Therefore, it is of great significance to study and develop a method for activating diaphragm materials. Summary of the Invention

[0008] The purpose of the present invention is to overcome the defects of the prior art that the use of hot sulfuric acid treatment leads to high energy consumption and high cost of the diaphragm material, and to provide a liquid flow battery diaphragm material and its activation method and a liquid flow battery. The activation method is carried out at room temperature, and the activation method can avoid the defects of using hot sulfuric acid, and can effectively improve the battery performance of the liquid flow battery diaphragm material.

[0009] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a method for activating a flow battery diaphragm material, wherein the activation method comprises: contacting the flow battery diaphragm material with an acid solution for activation treatment at room temperature in the presence of ultrasound.

[0010] The second aspect of the present invention provides a flow battery diaphragm material activated by the aforementioned activation method.

[0011] A third aspect of the present invention provides a liquid flow battery, wherein the liquid flow battery contains the liquid flow battery diaphragm material described above.

[0012] Through the above technical solution, the technical solution of the present invention has the following advantages:

[0013] (1) The activation method is different and can be operated at room temperature.

[0014] (2) The performance of the membrane material activated by this method is better than that of the material treated with acid at room temperature.

[0015] (3) Flow batteries have higher power density, current efficiency (CE), voltage efficiency (VE) and energy efficiency (EE). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic diagram comparing the change in power density of a flow battery containing the activated flow battery diaphragm material of Example 1 of the present invention and the unactivated diaphragm material of Comparative Example 1 with the change in current density;

[0017] Figure 2 This is a comparison chart of the current efficiency (CE), voltage efficiency (VE) and energy efficiency (EE) of a flow battery containing the activated flow battery diaphragm material of Example 1 of the present invention and the unactivated diaphragm material of Comparative Example 1.

[0018] Description of Reference Numerals

[0019] 1- Activated flow battery diaphragm material according to Example 1;

[0020] 2-Comparative Example 1: the diaphragm material without activation treatment. DETAILED DESCRIPTION

[0021] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0022] A first aspect of the present invention provides a method for activating a flow battery diaphragm material, wherein the activation method comprises: contacting the flow battery diaphragm material with an acid solution for activation treatment at room temperature in the presence of ultrasound.

[0023] The inventors of the present invention unexpectedly discovered that in the prior art, the use of hot sulfuric acid treatment leads to the defect of high energy consumption and high cost of the diaphragm material. The inventors of the present invention, under room temperature conditions, that is, without heating the acid solution, and using the ultrasonic field generated by ultrasound, caused the molecules, ions, bubbles, etc. in the liquid to continuously vibrate and transfer, thereby accelerating the transfer of protons in the diaphragm, which is beneficial to improving the performance of the diaphragm in the battery.

[0024] According to the present invention, preferably, the activation treatment conditions include: a temperature of 20-40°C for 5-30 minutes; more preferably, the activation treatment conditions include: a temperature of 25-35°C for 10-20 minutes. In the present invention, limiting the activation treatment conditions to the aforementioned ranges can maximize the performance of the diaphragm while reducing energy consumption and saving the time and cost of diaphragm treatment.

[0025] According to the present invention, the ultrasonic frequency of the ultrasonic wave is 1-8 kHz, preferably 2-7 kHz, and more preferably 3-6 kHz. In the present invention, the ultrasonic frequency of the ultrasonic wave is limited to the aforementioned range. The proton transfer constant of the flow battery diaphragm material is increased by ultrasonic action. The increase in this constant helps to promote the ion conductivity rate of the diaphragm material, thereby improving the performance of the diaphragm material in the flow battery, and further making the performance of the battery assembled with the activated diaphragm material better than that of the battery assembled with the untreated diaphragm material.

[0026] In the present invention, the ultrasonic instrument used is not specifically limited. For example, it can be an ultrasonic instrument purchased from Kunshan Ultrasonic Instrument Co., Ltd. with a model number of KQ3200DE.

[0027] According to the present invention, the acid solution is selected from one or more of sulfuric acid, hydrochloric acid, phosphoric acid and acetic acid; preferably, the acid solution is selected from one or more of hydrochloric acid, phosphoric acid and acetic acid; in the present invention, the aforementioned acid solution is used, which has relatively weak corrosiveness and low equipment requirements.

[0028] According to the present invention, the mass fraction of the acid solution is 5-15%, preferably 5-10%. In the present invention, the mass fraction of the acid solution is relatively low, and the corrosiveness and acidity are low, thereby reducing the equipment requirements.

[0029] According to the present invention, the flow battery membrane material is selected from one or more of perfluorosulfonic acid ion exchange membrane material, sulfonated polyetheretherketone membrane material and polyethersulfone membrane material; preferably, the flow battery membrane material is perfluorosulfonic acid ion exchange membrane material. In the present invention, the perfluorosulfonic acid ion exchange membrane material can be purchased from DuPont manufacturer, the model is Nafion series membrane, the parameters of the Nafion series membrane are 30m 2 / piece, width is 100cm.

[0030] The second aspect of the present invention provides a flow battery diaphragm material activated by the aforementioned activation method.

[0031] According to the present invention, the proton transfer constant of the flow battery membrane material is 55-66m 2 / s, and the ion conduction rate is (2.2-3.6)×10 -9 mS -1 .

[0032] A third aspect of the present invention provides a liquid flow battery, wherein the liquid flow battery contains the liquid flow battery diaphragm material described above.

[0033] According to the present invention, the power density of the flow battery is 410-500 mW / cm 2 , energy efficiency is 72-80%.

[0034] The present invention will be described in detail below through examples.

[0035] In the following examples and comparative examples:

[0036] The proton transfer constant and ion conduction rate were calculated from the electrochemical impedance spectroscopy test results, and the power density, current efficiency (CE), voltage efficiency (VE) and energy efficiency (EE) parameters were calculated from the constant current charge and discharge method test results.

[0037] The electrochemical impedance spectroscopy method uses an electrochemical workstation; the constant current charge and discharge method uses a charge and discharge tester;

[0038] The raw material of the perfluorosulfonic acid ion exchange membrane is a commercial product of DuPont with the brand name Nafion 115.

[0039] Example 1

[0040] This embodiment is intended to illustrate the activation treatment of a flow battery diaphragm material using the method of the present invention.

[0041] (1) Flow battery membrane material: Cut a piece of perfluorosulfonic acid ion exchange membrane material with a size of 10cm*10cm;

[0042] (2) In the presence of ultrasound, the flow battery diaphragm material cut in step (1) is placed in a 7% by mass sulfuric acid solution for activation treatment, wherein the temperature is 30° C., the ultrasonic frequency is 5 kHz, and the activation treatment time is 15 minutes.

[0043] As a result, the activated flow battery membrane material S1 was obtained, and the performance parameters are shown in Table 1.

[0044] Example 2

[0045] This embodiment is intended to illustrate the activation treatment of a flow battery diaphragm material using the method of the present invention.

[0046] An activated flow battery diaphragm material was prepared according to the same activation treatment method as in Example 1, except that: in step (2), the flow battery diaphragm material cut in step (1) was placed in a 5% by mass sulfuric acid solution for activation treatment, wherein the temperature was 25°C, the ultrasonic frequency was 3kHz, and the activation treatment time was 20 minutes.

[0047] As a result, the activated flow battery membrane material S2 was obtained, and the performance parameters are shown in Table 1.

[0048] Example 3

[0049] This embodiment is intended to illustrate the activation treatment of a flow battery diaphragm material using the method of the present invention.

[0050] An activated flow battery diaphragm material was prepared according to the same activation treatment method as in Example 1, except that: in step (2), the flow battery diaphragm material cut in step (1) was placed in a 10% by mass sulfuric acid solution for activation treatment, wherein the temperature was 35°C, the ultrasonic frequency was 6 kHz, and the activation treatment time was 10 minutes.

[0051] As a result, the activated flow battery membrane material S3 was obtained, and the performance parameters are shown in Table 1.

[0052] Example 4

[0053] This embodiment is intended to illustrate the activation treatment of a flow battery diaphragm material using the method of the present invention.

[0054] An activated flow battery diaphragm material was prepared according to the same activation treatment method as in Example 1, except that: in step (2), the flow battery diaphragm material cut in step (1) was placed in a 5% by mass sulfuric acid solution for activation treatment, wherein the temperature was 20°C, the ultrasonic frequency was 2kHz, and the activation treatment time was 30 minutes.

[0055] As a result, the activated flow battery membrane material S4 was obtained, and the performance parameters are shown in Table 1.

[0056] Example 5

[0057] This embodiment is intended to illustrate the activation treatment of a flow battery diaphragm material using the method of the present invention.

[0058] An activated flow battery diaphragm material was prepared according to the same activation treatment method as in Example 1, except that: in step (2), the flow battery diaphragm material cut in step (1) was placed in a 15% by mass sulfuric acid solution for activation treatment, wherein the temperature was 40°C, the ultrasonic frequency was 7 kHz, and the activation treatment time was 5 minutes.

[0059] As a result, the activated flow battery membrane material S5 was obtained, and the performance parameters are shown in Table 1.

[0060] Comparative Example 1

[0061] The flow battery diaphragm material used in the same step (1) as in Example 1, that is, without activation treatment, is marked as DS1, and the performance parameters are shown in Table 1.

[0062] Comparative Example 2

[0063] An activated flow battery diaphragm material was prepared according to the same activation treatment method as in Example 1, except that: Comparative Example 2 used the "hot sulfuric acid" method in the prior art, without ultrasound, and at a higher temperature. The specific method includes:

[0064] In step (2), the flow battery diaphragm material cut in step (1) is placed in a 15% by mass sulfuric acid solution for activation treatment, wherein the temperature is 80° C. and the activation treatment time is 30 minutes.

[0065] The results showed that the flow battery separator material DS2 was obtained, and the performance parameters are shown in Table 1.

[0066] Comparative Example 3

[0067] The activated flow battery diaphragm material was prepared by the same activation treatment method as in Example 1, except that:

[0068] In step (2), the flow battery diaphragm material cut in step (1) is placed in a 1% by mass sulfuric acid solution for activation treatment, wherein the temperature is 15° C., the ultrasonic frequency is 0.5 kHz, and the activation treatment time is 1 min.

[0069] As a result, the activated flow battery membrane material DS3 was obtained, and the performance parameters are shown in Table 1.

[0070] Comparative Example 4

[0071] The activated flow battery diaphragm material was prepared by the same activation treatment method as in Example 1, except that:

[0072] In step (2), the flow battery diaphragm material cut in step (1) is placed in a 20% by mass sulfuric acid solution for activation treatment, wherein the temperature is 45° C., the ultrasonic frequency is 10 kHz, and the activation treatment time is 35 minutes.

[0073] As a result, the activated flow battery membrane material DS4 was obtained, and the performance parameters are shown in Table 1.

[0074] Table 1

[0075] Example No. <![CDATA[Proton transfer constant (m 2 / s)]]> <![CDATA[Ionic conduction rate (10 -9 mS cm -1 )]]> Example 1 66 3.6 Example 2 60 3.0 Example 3 60 2.9 Example 4 55 2.5 Example 5 55 2.2 Comparative Example 1 39.8 1.59 Comparative Example 2 50 2.1 Comparative Example 3 30 1.3 Comparative Example 4 20 0.8

[0076] Application Example 1

[0077] The battery separator materials prepared in Examples 1-5 and Comparative Examples 1-4 were applied to flow batteries, and their (peak) power densities were tested. The results are shown in Table 2.

[0078] Table 2

[0079] Example No. <![CDATA[(Peak) power density (mW cm -2 )]]> Example 1 500 Example 2 470 Example 3 460 Example 4 420 Example 5 410 Comparative Example 1 338 Comparative Example 2 404 Comparative Example 3 305 Comparative Example 4 300

[0080] It can be seen from Table 2 that the power density of the flow batteries using the flow battery diaphragm materials of Examples 1-5 treated with the activation treatment method of the present invention is higher than that of Comparative Examples 1-4.

[0081] in addition, Figure 1 It is a comparative diagram showing the change in power density of a flow battery containing the activated flow battery diaphragm material of Example 1 of the present invention and the unactivated diaphragm material of Comparative Example 1 as a function of current density; wherein, "1" represents the activated flow battery diaphragm material of Example 1; and "2" represents the unactivated diaphragm material of Comparative Example 1. Figure 1 It shows that the maximum power of the flow battery containing the flow battery diaphragm material activated in Example 1 of the present invention can reach 500mWcm -2 Under the same conditions, the maximum power of the flow battery containing the unactivated diaphragm material of Comparative Example 1 is only 330mWcm-2 It can be seen from this that the activation treatment method of the present invention can quickly improve the performance of the membrane material at room temperature, thereby improving the performance of the flow battery.

[0082] Application Example 2

[0083] The battery separator materials prepared in Examples 1-5 and Comparative Examples 1-4 were applied to flow batteries, and their current efficiency (CE), voltage efficiency (VE) and energy efficiency (EE) were tested. The results are shown in Table 3.

[0084] Table 3

[0085] Example No. Current efficiency (CE, %) Voltage efficiency (VE,%) Energy efficiency (EE, %) Example 1 99 81 80 Example 2 99 77 76 Example 3 99 76 75 Example 4 97 75 73 Example 5 96 75 72 Comparative Example 1 82 63 52 Comparative Example 2 95 71 67 Comparative Example 3 80 60 48 Comparative Example 4 80 65 52

[0086] It can be seen from Table 3 that the flow battery diaphragm materials of Examples 1-5 treated with the activation method of the present invention are applied to flow batteries, and their current efficiency (CE), voltage efficiency (VE) and energy efficiency (EE) are higher than those of Comparative Examples 1-4.

[0087] in addition, Figure 2 This figure compares the current efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of a flow battery containing the activated flow battery separator material of Example 1 and the unactivated separator material of Comparative Example 1. "1" represents the activated flow battery separator material of Example 1; "2" represents the unactivated separator material of Comparative Example 1. Figure 2 The results show that the current efficiency (CE), voltage efficiency (VE), and energy efficiency (EE) of the flow battery diaphragm material activated in Example 1 of the present invention are all higher than those of the unactivated diaphragm material in Comparative Example 1. This shows that the flow battery diaphragm material activated by the present invention has excellent performance in flow batteries.

[0088] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for activating a flow battery diaphragm material, characterized in that: The activation method comprises: contacting the flow battery diaphragm material with an acid solution in the presence of ultrasonic waves for activation treatment; The activation treatment conditions include: a temperature of 25-35° C. and an activation treatment time of 10-20 minutes; The ultrasonic frequency of the ultrasonic wave is 1-8kHz; The acid solution is sulfuric acid, and the mass fraction of the acid solution is 5-15%; The flow battery diaphragm material is a perfluorosulfonic acid ion exchange membrane material.

2. The activation method according to claim 1, wherein The ultrasonic frequency of the ultrasonic wave is 2-7 kHz.

3. The activation method according to claim 1, wherein The ultrasonic frequency of the ultrasonic wave is 3-6 kHz.

4. The activation method according to claim 1, wherein The mass fraction of the acid solution is 5-10%.

5. A flow battery diaphragm material activated by the activation method according to any one of claims 1 to 4.

6. The flow battery separator material according to claim 5, wherein: The proton transfer constant of the flow battery membrane material is 55-66 m 2 / s, and the ion conduction rate is (2.2-3.6)×10 -9 mS -1 .

7. A flow battery, characterized in that: The flow battery comprises the flow battery separator material according to claim 5 or 6.

8. The flow battery according to claim 7, wherein: The power density of the flow battery is 410-500 mW / cm 2 , energy efficiency is 72-80%.

Images