Ion crossing prevention asymmetric diaphragm for iron-sulfur flow battery as well as preparation method and application of asymmetric diaphragm

Abstract

The invention relates to the technical field of electrochemistry, and provides an anti-ion crossing asymmetric diaphragm for an iron-sulfur flow battery as well as a preparation method and application of the anti-ion crossing asymmetric diaphragm. The asymmetric diaphragm comprises a base membrane and a graphdiyne coating covering the base membrane, the graphdiyne coating is prepared from the following raw materials in percentage by weight: 90%-98.5% of graphdiyne, 1%-9.5% of a binder and 0.5% of a wetting agent. According to the present invention, the graphdiyne coating layer covers the base membrane, and the coating layer comprises the graphdiyne, the binder and the wetting agent, such that when the flow battery stack is assembled, the side coated with the graphdiyne coating layer faces the negative electrode side, and the large specific surface area of the graphdiyne can adsorb the polysulfide ions going to penetrate through the diaphragm to shuttle towards the positive electrode side so as to achieve the liquid flow battery stack assembly; and after adsorption, due to the fact that the surface carries charges of the same kind as the polysulfide ions, a certain electrostatic shielding effect can be achieved, shuttling and crossing of the polysulfide ions are hindered, and the selectivity of the diaphragm is improved. The modification of the graphdiyne coating also helps to improve the stability of the diaphragm and reduce swelling.

Description

Technical Field

[0001] The present disclosure relates to the field of electrochemical technology, and in particular to an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, and a preparation method and application thereof. Background Art

[0002] Long-duration energy storage systems have the potential to enhance the capacity to absorb new energy and replace traditional power generation methods. They can provide the power grid with ample flexible regulation resources, reduce grid operating costs, and offer greater peak-valley arbitrage and market profit potential. With the increasing penetration of renewable energy generation, the demand for long-duration energy storage systems is also growing. Long-duration energy storage includes pumped hydro, compressed air energy storage, and flow batteries. Flow batteries can achieve amplitude and frequency modulation and smooth output through large-capacity energy storage devices. Energy and power can be decoupled for control, improving the continuity, stability, and controllability of renewable energy generation and reducing the impact of large-scale renewable energy generation on the power grid. Under the guidance of relevant policies in the long-duration energy storage field, demonstration projects have performed well and are considered one of the most suitable battery technologies for long-duration energy storage.

[0003] Currently, the most technologically mature and industrialized all-vanadium flow battery faces problems such as expensive vanadium electrolytes, limited room for cost reduction, large fluctuations in vanadium resource prices, and the corrosiveness of strong acid electrolytes, which to a certain extent restrict its development. In contrast, neutral iron-sulfur flow batteries have great development potential due to the abundant and stable sources of positive and negative active materials, low cost, and low corrosiveness, and are expected to become one of the main development directions of the new generation of flow batteries. However, since different ions are used as active materials on the positive and negative sides, there is a hidden danger of cross-miscibility of active ions in the positive and negative electrolytes. In particular, there is the notorious shuttle effect of polysulfide pairs in the negative electrode electrolyte. Due to the cross-pollination of polysulfide pairs, the battery cycle life is poor, which hinders its successful commercialization.

[0004] Therefore, it is crucial to develop iron-sulfur flow battery separators that prevent electrolyte cross-miscibility. Summary of the Invention

[0005] The present disclosure aims to solve at least one of the problems existing in the prior art and provide an asymmetric diaphragm for iron-sulfur liquid flow batteries that prevents ion crossover, and a preparation method and application thereof.

[0006] In one aspect of the present disclosure, an asymmetric diaphragm for an iron-sulfur flow battery that prevents ion crossover is provided, wherein the asymmetric diaphragm comprises a base membrane and a graphyne coating covering the base membrane; wherein

[0007] The graphyne coating is made of the following raw materials in percentage by weight: 90% to 98.5% graphyne, 1% to 9.5% binder, and 0.5% wetting agent.

[0008] Optionally, the binder is polyvinylidene fluoride (PVDF).

[0009] Optionally, the wetting agent is a silanol nonionic surfactant.

[0010] Optionally, the base membrane is one of a sulfonated polyetheretherketone (SPEEK) membrane, a perfluorosulfonic acid membrane (Nafion) membrane, and a polybenzimidazole (PBI) membrane.

[0011] Another aspect of the present disclosure provides a method for preparing an asymmetric diaphragm for an iron-sulfur flow battery that prevents ion crossover, the method comprising:

[0012] According to weight percentage, 90% to 98.5% of graphyne, 1% to 9.5% of binder, and 0.5% of wetting agent are weighed respectively;

[0013] The graphyne, binder and wetting agent are continuously stirred in N-methylpyrrolidone (NMP), and vacuum degassed at a speed of 200 rpm / min to 400 rpm / min for 1 h to 3 h to prepare a uniform coating slurry;

[0014] The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

[0015] Optionally, the binder is polyvinylidene fluoride (PVDF).

[0016] Optionally, the wetting agent is a silanol nonionic surfactant.

[0017] Optionally, the base membrane is one of a sulfonated polyetheretherketone (SPEEK) membrane, a perfluorosulfonic acid membrane (Nafion) membrane, and a polybenzimidazole (PBI) membrane.

[0018] Optionally, the graphyne, binder and wetting agent are continuously stirred in N-methylpyrrolidone (NMP), and vacuum degassed at a speed of 200 rpm / min to 400 rpm / min for 1 h to 3 h to prepare a uniform coating slurry, comprising:

[0019] The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 200 rpm / min for 3 h to prepare a uniform coating slurry.

[0020] Another aspect of the present disclosure provides an application of an asymmetric diaphragm that prevents ion crossover in a liquid flow battery, wherein the asymmetric diaphragm is the asymmetric diaphragm described above; or, the asymmetric diaphragm is prepared using the method described above.

[0021] Compared to the prior art, the present invention covers the base membrane with a Graphdene coating, which is composed of Graphdene, a binder, and a wetting agent. When assembling the flow battery stack, the side coated with the Graphdene coating faces the negative electrode. The larger specific surface area of ​​Graphdene can adsorb polysulfide ions that attempt to pass through the diaphragm to the positive electrode. After adsorption, the surface carries the same charge as the polysulfide ions, which can play a certain electrostatic shielding role, hindering the cross-transmission of polysulfide ions and improving the selectivity of the diaphragm. In addition, the modification of the Graphdene coating also helps to improve the stability of the diaphragm and reduce swelling. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0023] Figure 1 The present invention provides a flowchart of a method for preparing an asymmetric diaphragm for iron-sulfur liquid flow batteries that prevents ion crossover, according to one embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present disclosure, many technical details are provided to enable readers to better understand the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present disclosure can be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present disclosure. The various embodiments can be combined and referenced with each other under the premise that there is no contradiction.

[0025] One embodiment of the present disclosure relates to an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover. The asymmetric diaphragm includes a base membrane and a graphyne coating covering the base membrane; wherein the graphyne coating is made of the following raw materials in percentage by weight: 90% to 98.5% graphyne, 1% to 9.5% binder, and 0.5% wetting agent.

[0026] The asymmetric diaphragm for the iron-sulfur liquid flow battery with ion crossover prevention of the disclosed embodiment is coated with a Graphdene coating on the base membrane. The coating is composed of Graphdene, a binder and a wetting agent. When assembling the liquid flow battery stack, the side coated with the Graphdene coating faces the negative electrode side. The larger specific surface area of ​​Graphdene can adsorb polysulfide ions that want to pass through the diaphragm to the positive electrode side. After adsorption, the surface carries the same charge as the polysulfide ions, which can play a certain electrostatic shielding role, hindering the crossover of polysulfide ions and improving the selectivity of the diaphragm. In addition, the modification of the Graphdene coating also helps to improve the stability of the diaphragm and reduce swelling.

[0027] Optionally, the binder is polyvinylidene fluoride (PVDF), the wetting agent is a silanol-based nonionic surfactant, and the base membrane is one of a sulfonated polyetheretherketone (SPEEK) membrane, a perfluorosulfonic acid membrane (Nafion) membrane, and a polybenzimidazole (PBI) membrane.

[0028] The following will illustrate the asymmetric diaphragm for the iron-sulfur liquid flow battery with ion crossover prevention disclosed in the present invention in several embodiments.

[0029] Example 1

[0030] An asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the asymmetric diaphragm comprising a base membrane and a graphyne coating covering the base membrane; wherein the graphyne coating is made of the following raw materials in percentage by weight: 90% graphyne, 9.5% binder, and 0.5% wetting agent.

[0031] Example 2

[0032] An asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the asymmetric diaphragm comprising a base membrane and a graphyne coating covering the base membrane; wherein the graphyne coating is made of the following raw materials in percentage by weight: 98.5% graphyne, 1% binder, and 0.5% wetting agent.

[0033] Example 3

[0034] An asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the asymmetric diaphragm comprising a base membrane and a graphyne coating covering the base membrane; wherein the graphyne coating is made of the following raw materials in percentage by weight: 95% graphyne, 4.5% binder, and 0.5% wetting agent.

[0035] Example 4

[0036] An asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the asymmetric diaphragm comprising a base membrane and a graphyne coating covering the base membrane; wherein the graphyne coating is made of the following raw materials in percentage by weight: 94.5% graphyne, 5% binder, and 0.5% wetting agent.

[0037] Another aspect of the present disclosure provides a method for preparing an asymmetric diaphragm for an iron-sulfur flow battery that prevents ion crossover, such as Figure 1 As shown, the method includes:

[0038] Step S110 , weighing 90% to 98.5% of graphyne, 1% to 9.5% of a binder, and 0.5% of a wetting agent respectively by weight percentage.

[0039] Step S120, continuously stirring the graphyne, binder and wetting agent in N-methylpyrrolidone (NMP), and vacuum degassing at a speed of 200 rpm / min to 400 rpm / min for 1 hour to 3 hours to prepare a uniform coating slurry;

[0040] Step S130: evenly coating the slurry on the base film, and obtaining an asymmetric diaphragm after drying.

[0041] The method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover according to the embodiment of the present disclosure is to cover the base membrane with a graphene coating, which is composed of graphene, a binder, and a wetting agent. When assembling the liquid flow battery stack, the side coated with the graphene coating faces the negative electrode side, and the larger specific surface area of ​​graphene can be used to adsorb polysulfide ions that want to pass through the diaphragm to the positive electrode side. After adsorption, the surface carries the same charge as the polysulfide ions, which can play a certain electrostatic shielding role, hinder the crossover of polysulfide ions, and improve the selectivity of the diaphragm. In addition, the modification of the graphene coating also helps to improve the stability of the diaphragm and reduce swelling.

[0042] Optionally, the binder is polyvinylidene fluoride (PVDF).

[0043] Optionally, the wetting agent is a silanol nonionic surfactant.

[0044] Optionally, the base membrane is one of a sulfonated polyetheretherketone (SPEEK) membrane, a perfluorosulfonic acid membrane (Nafion) membrane, and a polybenzimidazole (PBI) membrane.

[0045] Optionally, the graphyne, binder and wetting agent are continuously stirred in N-methylpyrrolidone NMP, and vacuum degassing is performed at a rotation speed of 200 rpm / min to 400 rpm / min, and the stirring time is 1 hour to 3 hours, to prepare a uniform coating slurry, comprising: continuously stirring the graphyne, binder and wetting agent in N-methylpyrrolidone NMP, and vacuum degassing is performed at a rotation speed of 200 rpm / min, and the stirring time is 3 hours, to prepare a uniform coating slurry.

[0046] The following will describe in detail the method for preparing the asymmetric diaphragm for iron-sulfur liquid flow battery with ion crossover prevention disclosed in the present invention in several embodiments.

[0047] Example 5

[0048] A method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the method comprising:

[0049] Calculated by weight percentage, 90% of graphyne, 9.5% of binder, and 0.5% of wetting agent were weighed respectively.

[0050] The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 200 rpm / min for 3 h to prepare a uniform coating slurry.

[0051] The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

[0052] Example 6

[0053] A method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the method comprising:

[0054] Calculated by weight percentage, 98.5% of graphyne, 1% of binder, and 0.5% of wetting agent were weighed respectively.

[0055] The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 400 rpm / min for 1 h to prepare a uniform coating slurry.

[0056] The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

[0057] Example 7

[0058] A method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the method comprising:

[0059] Calculated by weight percentage, 98.5% of graphyne, 1% of binder, and 0.5% of wetting agent were weighed respectively.

[0060] The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 200 rpm / min for 3 h to prepare a uniform coating slurry.

[0061] The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

[0062] Example 8

[0063] A method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, the method comprising:

[0064] According to weight percentage, 95% of graphyne, 4.5% of binder and 0.5% of wetting agent were weighed respectively.

[0065] The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 200 rpm / min for 3 h to prepare a uniform coating slurry.

[0066] The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

[0067] Another aspect of the present disclosure provides an application of an asymmetric diaphragm that prevents ion crossover in a liquid flow battery, wherein the asymmetric diaphragm adopts the asymmetric diaphragm described above; or, the asymmetric diaphragm is prepared by the method described above. For details, please refer to the relevant records above and will not be repeated here.

[0068] The application of the asymmetric diaphragm with anti-ion crossover in the liquid flow battery of the embodiment of the present disclosure is that the asymmetric diaphragm is covered with a graphene coating on the base membrane. The coating is composed of graphene, a binder and a wetting agent. When assembling the liquid flow battery stack, the side coated with the graphene coating faces the negative electrode side. The larger specific surface area of ​​graphene can adsorb polysulfide ions that want to pass through the diaphragm to the positive electrode side. After adsorption, because the surface carries the same charge as the polysulfide ions, it can play a certain electrostatic shielding role, hindering the crossover of polysulfide ions and improving the selectivity of the diaphragm. In addition, the modification of the graphene coating also helps to improve the stability of the diaphragm and reduce swelling.

[0069] Those skilled in the art will appreciate that the above-mentioned embodiments are specific embodiments for implementing the present disclosure, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present disclosure.

Claims

1. An asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, characterized in that: The asymmetric diaphragm includes a base film and a graphyne coating covering the base film; wherein, The graphyne coating is made of the following raw materials in percentage by weight: 90% to 98.5% graphyne, 1% to 9.5% binder, and 0.5% wetting agent.

2. The asymmetric diaphragm according to claim 1, characterized in that The binder is polyvinylidene fluoride (PVDF).

3. The asymmetric diaphragm according to claim 1, characterized in that The wetting agent is a silanol nonionic surfactant.

4. The asymmetric diaphragm according to any one of claims 1 to 3, characterized in that The base membrane is one of a sulfonated polyetheretherketone SPEEK membrane, a perfluorosulfonic acid membrane Nafion membrane, and a polybenzimidazole PBI membrane.

5. A method for preparing an asymmetric diaphragm for an iron-sulfur liquid flow battery that prevents ion crossover, characterized in that: The method comprises: According to weight percentage, 90% to 98.5% of graphyne, 1% to 9.5% of binder, and 0.5% of wetting agent are weighed respectively; The graphyne, binder and wetting agent are continuously stirred in N-methylpyrrolidone (NMP), and vacuum degassed at a speed of 200 rpm / min to 400 rpm / min for 1 h to 3 h to prepare a uniform coating slurry; The slurry is evenly coated on a base film, and an asymmetric diaphragm is obtained after drying.

6. The method according to claim 5, characterized in that The binder is polyvinylidene fluoride (PVDF).

7. The method according to claim 5, characterized in that The wetting agent is a silanol nonionic surfactant.

8. The method according to any one of claims 5 to 7, characterized in that The base membrane is one of a sulfonated polyetheretherketone SPEEK membrane, a perfluorosulfonic acid membrane Nafion membrane, and a polybenzimidazole PBI membrane.

9. The method according to any one of claims 5 to 7, characterized in that The graphyne, binder and wetting agent are continuously stirred in N-methylpyrrolidone (NMP), and vacuum degassing is performed at a speed of 200 rpm / min to 400 rpm / min and a stirring time of 1 hour to 3 hours to prepare a uniform coating slurry, comprising: The graphyne, binder and wetting agent were continuously stirred in N-methylpyrrolidone (NMP) and vacuum degassed at a speed of 200 rpm / min for 3 h to prepare a uniform coating slurry.

10. Application of an asymmetric diaphragm for preventing ion crossover in a flow battery, characterized in that: The asymmetric diaphragm is the asymmetric diaphragm according to any one of claims 1 to 4; or, the asymmetric diaphragm is prepared by the method according to any one of claims 5 to 9.

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