Preparation method of ATP (adenosine triphosphate) polymer composite diaphragm for flow battery

Abstract

The invention provides a preparation method of an ATP (Adenosine Triphosphate) polymer composite diaphragm for a flow battery, which comprises the following steps of: preparing a polymer composite diaphragm containing ATP-X by taking sulfonated polyetheretherketone or recycled perfluorosulfonic acid as a base membrane, preparing an ATP-X material at first, then preparing SPEEK (Sulfonated Polyetheretherketone) fiber or recycling a perfluorosulfonic acid membrane, and finally preparing the polymer composite diaphragm. The polymer composite diaphragm prepared by the invention can realize long-time stable cycle operation in a flow battery, and is not limited to a single flow battery system.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid flow batteries, and in particular relates to a method for preparing an ATP polymer composite diaphragm for a liquid flow battery. Background Art

[0002] In recent years, the new energy industry, mainly photovoltaic and wind power, has developed rapidly. However, due to the geographical limitations, discontinuity and instability of wind power and photovoltaic, they cannot be well integrated into the power grid. Liquid flow batteries not only play the role of peak shaving and valley filling, but also have good safety.

[0003] The diaphragm is a key component of flow batteries, preventing cross-contamination between the positive and negative electrolytes and conducting ions to complete the circuit. An ideal composite diaphragm requires the following properties: high proton conductivity, high ion selectivity, high chemical stability, and low cost. Currently, the primary diaphragm material used both domestically and internationally is DuPont's Nafion series membranes. These membranes suffer from significant raw material pollution, severe ion permeation, and high cost, limiting the commercial application of flow batteries in large-scale energy storage. Consequently, numerous researchers have conducted extensive research on composite diaphragms for flow batteries. While these have significantly improved certain aspects of their performance, these diaphragms still suffer from high cost, poor overall performance, complex fabrication processes, and incompatibility with diverse flow battery systems, making them unsuitable for commercial flow battery applications. Therefore, developing a low-cost composite diaphragm with a long service life, excellent overall performance, and compatibility with diverse systems is an urgent challenge to promote the large-scale application of flow batteries. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing an ATP polymer composite membrane for a liquid flow battery, so as to achieve long-term stable cycle operation of the liquid flow battery and solve the problem in the prior art that the membrane can only be used for a single liquid flow battery system.

[0005] The technical solution adopted by the present invention is a method for preparing an ATP polymer composite membrane for a flow battery, and the preparation steps are as follows: Step S1, preparing ATP-X material: S11, adding attapulgite to a solution of sulfuric acid, potassium chloride or sodium chloride, and stirring at room temperature to form a suspension; S12, centrifuging the suspension obtained in S11 and washing it alternately with ultrapure water and ethanol until the supernatant is neutral after the last wash, pouring out the supernatant, and the precipitate below is ionized ATP-X; S13, removing the ionized ATP-X layer, drying, ball milling and sieving to obtain ATP-X material; Step S2, preparing SPEEK fiber or strip-shaped perfluorosulfonic acid membrane; Step S3, preparing a polymer composite membrane containing ATP-X.

[0006] Furthermore, the SPEEK fiber preparation steps described in S2 are as follows: S21, sulfonating the polyetheretherketone powder with concentrated sulfuric acid to obtain a reddish-brown mixed solution; S22, slowly pouring the reddish-brown mixed solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing with deionized water until neutral, and then drying in the shade at room temperature to obtain dry SPEEK fiber. For non-proton conducting liquid flow battery systems, proceed to S23, and for proton conducting liquid flow battery systems, directly proceed to S3; S23, ionizing the prepared SPEEK fiber with one of a KOH solution or a NaOH solution, then immersing and washing the fiber in deionized water until the fiber becomes neutral, and then drying the fiber in the shade at room temperature to obtain the ionized SPEEK fiber.

[0007] Furthermore, the steps for preparing the strip-shaped perfluorosulfonic acid membrane described in S2 are as follows: : The recovered perfluorosulfonic acid proton exchange membrane is fully washed with sulfuric acid, washed with ultrapure water and dried, and then cut into strips to obtain strip perfluorosulfonic acid membrane. For the non-proton conductive flow battery system, continue to , proton-conducting flow battery system, directly conducts S3; The strip-shaped perfluorosulfonic acid membrane is ionized with one of a KOH solution or a NaOH solution, then immersed and cleaned in deionized water until neutral, and then dried in the shade at room temperature to obtain an ionized strip-shaped perfluorosulfonic acid membrane.

[0008] Furthermore, if SPEEK fiber is prepared in S2, the preparation steps of S3 are as follows: S31, adding SPEEK fiber to the dimethyl sulfoxide solution and stirring continuously until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, adding ATP-X to the SPEEK dimethyl sulfoxide diaphragm casting solution of S31 to prepare an ATP-X / SPEEK mixed solution; S33, pouring the mixed solution obtained in S32 onto a glass plate, and drying it twice to obtain an ATP-X / SPEEK polymer composite membrane.

[0009] Furthermore, if a strip-shaped perfluorosulfonic acid membrane is prepared in S2, the preparation steps of S3 are as follows: , adding the strip-shaped perfluorosulfonic acid membrane into the dimethylacetamide solution and stirring continuously until a perfluorosulfonic acid dimethylacetamide diaphragm casting solution without any solid phase residue is obtained; ATP-X was added to the perfluorosulfonic acid dimethylacetamide diaphragm casting solution, stirred until completely dispersed, and then ultrasonically treated to prepare an ATP-X / PFSA mixed solution; ,Will The obtained mixed solution was poured onto a glass plate and dried twice to obtain an ATP-X / PFSA polymer composite membrane.

[0010] Furthermore, the ATP-X material described in S1 is ATP-H + , ATP-K + or ATP-Na + , In S11, 1-10 g of attapulgite is taken, the solution concentration is 0.1-1.0 M, and the stirring time is 12-24 h; In the S12, the centrifugal speed is 6000-8000 rad / min; In the S13, the ball milling speed is 200-400 rad / min, and the ball milling time is 10-20 min.

[0011] Furthermore, in the S21, the mass volume ratio of polyetheretherketone powder to concentrated sulfuric acid is 1:(13-15) g / mL, and the mixture is stirred at a speed of 700-900 r / min for 65-80 min at 50-60°C.

[0012] Furthermore, in said S31, the mass volume ratio of the SPEEK fiber to the dimethyl sulfoxide solution is 1:(17-32) g / mL, and the temperature during stirring is 50-60°C; In the S32, ATP-X is maintained at 1-5 wt% of the SPEEK fiber, the stirring temperature is 50-60°C, and the ultrasonic time is 5-10 min; In the step S33, the product is first dried at 70-80° C. for 12-24 hours, and then dried at 100-120° C. for 5-12 hours.

[0013] Furthermore, the In the experiment, the mass volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution was 1:(26-28) g / mL, and the stirring temperature was 50-60 °C. described In the experiment, ATP-X was maintained at 1-3 wt% of the dried PFSA strip film, the stirring temperature was 50-60 °C, and the ultrasonic time was 5-10 min. described First dry at 70~80℃ for 12~24h, then dry at 100~120℃ for 5~12h.

[0014] Furthermore, after the sulfonation reaction is completed, the sulfonation degree of the sulfonated polyetheretherketone is 55% to 65%.

[0015] The beneficial effects of the present invention are: 1. The present invention performs functionalized ion exchange on attapulgite (ATP) materials. Due to isomorphous substitution, some trivalent cations such as Al (III) and Fe (III) partially replace Mg in the octahedral position. Structural defects on the surface and in the pores of natural attapulgite give it a surface negative charge. The cations exchanged in the pores prevent the penetration of active substances while increasing the transmission rate of cations supporting the electrolyte, effectively improving the selectivity of the diaphragm, and enhancing the efficiency and cycle stability of the flow battery.

[0016] 2. When the present invention is implemented in a neutral or alkaline system, the base material sulfonated polyetheretherketone (SPEEK) or perfluorosulfonic acid (PFSA) is subjected to alkali treatment to prepare a composite membrane that is a sodium ion type or potassium ion type composite membrane, which can provide abundant ion-carrying groups, improve the ion conductivity, significantly reduce the active ion permeability, and improve the performance of the flow battery. The prepared composite membrane can adapt to various systems of redox flow batteries and has very wide applicability to flow batteries, which will help promote the commercial development of various types of flow batteries.

[0017] 3. The composite membrane preparation process of the present invention uses raw materials with abundant reserves in my country, low cost and green environmental protection. The equipment used is easy to operate and the preparation process is very simple, which will help promote the development of commercial composite membrane materials for liquid flow batteries and promote the commercial production of liquid flow batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is the SEM image of attapulgite without ionization treatment.

[0020] Figure 2 These are the XRD patterns of attapulgite before and after modification and the composite films prepared with different addition percentages.

[0021] Figure 3 This is a SEM image of the composite membrane prepared in Example 3.

[0022] Figure 4 These are the charge and discharge curves of Examples 1 to 6, wherein (a) and (c) are the charge and discharge curves of Example 1 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (b) and (d) are the charge and discharge curves of Example 2 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (e) and (f) are the charge and discharge curves of Example 3 and Example 4 in iron liquid flow batteries, respectively; and (g) and (h) are the charge and discharge curves of Example 5 and Example 6 in zinc-iron liquid flow batteries, respectively.

[0023] Figure 5 3 and 4 are capacity retention rate comparison diagrams of Examples 1 to 2 and 5 to 6 of the present invention, wherein (a) and (c) are capacity retention rate comparison diagrams of Example 1 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (b) and (d) are capacity retention rate comparison diagrams of Example 2 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (e) and (f) are capacity retention rate comparison diagrams of Example 5 and Example 6 in zinc-iron liquid flow batteries, respectively.

[0024] Figure 6 1 is a comparison chart of the coulombic efficiencies of Examples 1 to 2 and 5 to 6 of the present invention, wherein (a) and (c) are comparison charts of the coulombic efficiencies of Example 1 in all-vanadium and vanadium-titanium flow batteries, respectively; (b) and (d) are comparison charts of the coulombic efficiencies of Example 2 in all-vanadium and vanadium-titanium flow batteries, respectively; and (e) and (f) are comparison charts of the coulombic efficiencies of Examples 5 and 6 in zinc-iron flow batteries, respectively.

[0025] Figure 7 3 are energy efficiency comparison diagrams of Examples 1 to 2 and 5 to 6 of the present invention, wherein (a) and (c) are energy efficiency comparison diagrams of Example 1 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (b) and (d) are energy efficiency comparison diagrams of Example 2 in all-vanadium and vanadium-titanium liquid flow batteries, respectively; (e) and (f) are energy efficiency comparison diagrams of Example 5 and Example 6 in zinc-iron liquid flow batteries, respectively.

[0026] Figure 8It is a comparison diagram of the long-cycle efficiencies of Example 3, Example 4, Comparative Example 1, Comparative Example 2, Example 10, Comparative Example 10, Comparative Example 11, and Comparative Example 13 of the present invention, wherein (a) is a comparison diagram of the long-cycle efficiencies of Example 3 in an iron-flow liquid battery, (b) is a comparison diagram of the long-cycle efficiencies of Example 4 in an iron-flow liquid battery, (c) is a comparison diagram of the long-cycle efficiencies of Comparative Example 1 in an iron-flow liquid battery, (d) is a comparison diagram of the long-cycle efficiencies of Comparative Example 2 in an iron-flow liquid battery, (e) is a comparison diagram of the long-cycle efficiencies of Example 10 in an iron-flow liquid battery, (f) is a comparison diagram of the long-cycle efficiencies of Comparative Example 10 in an iron-flow liquid battery, (g) is a comparison diagram of the long-cycle efficiencies of Comparative Example 11 in an iron-flow liquid battery, and (h) is a comparison diagram of the long-cycle efficiencies of Comparative Example 13 in an iron-flow liquid battery; in the figure, CE represents coulombic efficiency, EE represents energy retention rate, and DC represents discharge capacity.

[0027] Figure 9 This is a comparison chart of the magnifications tested in Example 3 of the present invention.

[0028] Figure 10 This is a comparison chart of peak power density tested in Example 3 of the present invention.

[0029] Figure 11 This is the SEM image of Example 3.

[0030] Figure 12 This is the SEM image of Comparative Example 3.

[0031] Figure 13 These are the capacity retention rate and coulombic efficiency diagrams of Comparative Example 3, Comparative Example 4, and Example 7, wherein (a) is the capacity retention rate and coulombic efficiency diagram of Comparative Example 3 in the iron flow liquid battery, (b) is the capacity retention rate and coulombic efficiency diagram of Comparative Example 3 in the iron flow liquid battery, and (c) is the capacity retention rate and coulombic efficiency diagram of Example 7 in the iron flow liquid battery.

[0032] Figure 14 This is the SEM image of Comparative Example 4.

[0033] Figure 15 This is the SEM image of Example 7.

[0034] Figure 16 This is the capacity-voltage diagram of Comparative Example 1.

[0035] Figure 17 This is a graph of the capacity retention rate of Comparative Example 2.

[0036] Figure 18 This is a TEM image of the modified attapulgite according to Example 3 of the present invention.

[0037] Figure 19This is a charge and discharge test curve diagram of Example 8 of the present invention.

[0038] Figure 20 This is a diagram of the capacity retention rate of Example 8 of the present invention.

[0039] Figure 21 This is a Coulomb efficiency diagram of Example 8 of the present invention.

[0040] Figure 22 This is an energy efficiency diagram of Example 8 of the present invention.

[0041] Figure 23 This is a charge and discharge test curve diagram of Example 9 of the present invention.

[0042] Figure 24 This is a diagram of the capacity retention rate of Example 9 of the present invention.

[0043] Figure 25 4 is a Coulomb efficiency diagram of Example 9 of the present invention.

[0044] Figure 26 This is an energy efficiency diagram of Example 9 of the present invention. DETAILED DESCRIPTION

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] The embodiment of the present invention provides a method for preparing an ATP polymer composite membrane for a flow battery. The specific preparation steps are as follows: Step S1, prepare ATP-X material (ATP-X material is ATP-H + , ATP-K + or ATP-Na + ), the specific preparation steps are as follows: S11, weigh 1-10 g of attapulgite, add it to a solution of sulfuric acid, potassium chloride or sodium chloride with a concentration of 0.1-1.0 M, and magnetically stir it at room temperature for 12-24 hours to form a suspension. During the stirring process, the cations in the solution and the metal ions of the attapulgite are fully exchanged, so that the metal ions inside the crystal structure of the attapulgite are exchanged for the cations in the solution. The SEM image of the attapulgite without ionization treatment is shown in FIG. Figure 1 As shown; S12, centrifuge the suspension obtained in S11 at a speed of 6000-8000 rad / min, and wash it alternately with ultrapure water and ethanol until the supernatant is neutral after washing. Pour off the supernatant, and the precipitate below is ionized ATP; S13, remove the ionized ATP layer, place it in a vacuum drying oven to dry, then ball mill (dry mill) at a speed of 200-400 rad / min for 10-20 minutes, and then sieve it with a sieve to obtain ATP-X material.

[0047] Step 2: Prepare SPEEK fiber or perfluorosulfonic acid membrane. The specific steps are as follows: S21, sulfonating polyetheretherketone (PEEK) powder with 98 wt% concentrated sulfuric acid at a mass volume ratio of PEEK to concentrated sulfuric acid of 1:(13-15) g / mL, stirring at 700-900 rpm for 65-80 min at 50-60°C to obtain a reddish-brown mixed solution of concentrated sulfuric acid and sulfonated polyetheretherketone; S22. Slowly pour the reddish-brown mixed solution of S21 into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly wash it with deionized water until it is neutral. After drying in the shade at room temperature (25°C), place it in an oven to dry to obtain dry SPEEK fiber. The sulfonation degree of SPEEK is measured by existing technology to determine the chain segment ratio of the grafted sulfonic acid group, that is, the degree of introduction of the sulfonate group. If it does not meet expectations, the sulfonation time is adjusted accordingly according to the degree of sulfonation. In the present invention, the sulfonation degree of the sulfonated polyetheretherketone needs to be maintained at 55% to 65%.

[0048] S21-S22 can be replaced by: fully pickling the recovered Nafion212 membrane (perfluorosulfonic acid proton exchange membrane) with sulfuric acid, washing it with ultrapure water and drying it, and then cutting it into strips to obtain strips of perfluorosulfonic acid (PFSA) membrane. For non-proton conducting flow battery systems, proceed to S23; for proton conducting flow battery systems, proceed directly to step S3. S23, for a non-proton conducting flow battery system, the prepared SPEEK fiber or strip-shaped perfluorosulfonic acid membrane is ionized with a KOH solution or a NaOH solution, then washed and soaked in deionized water until neutral, and then dried in the shade at room temperature to obtain an ionized SPEEK fiber or an ionized strip-shaped perfluorosulfonic acid membrane.

[0049] Step S3, preparing a polymer composite membrane containing ATP-X, the specific steps are as follows: S31, taking 1.6-2.95 g of the SPEEK fiber prepared in step S2, adding it to the dimethyl sulfoxide solution, with the mass volume ratio of SPEEK fiber to dimethyl sulfoxide solution being 1:(17-32) g / mL, and then stirring at 50-60 °C until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; Alternatively, 1.78-1.9 g of the prepared perfluorosulfonic acid membrane strip was added to a dimethylacetamide solution at a mass-to-volume ratio of 1:(26-28) g / mL. The mixture was then stirred at 50-60°C until a PFSA dimethylacetamide membrane casting solution with no solid residue was obtained. S32: Add 0.0165-0.1475 g of ATP-X to the SPEEK dimethyl sulfoxide membrane casting solution of S31, or add 0.0178-0.057 g of ATP-X to the PFSA dimethylacetamide membrane casting solution of S31 (ATP-X is maintained at 1-5 wt% of the SPEEK fiber obtained in S2, or 1-3 wt% of the perfluorosulfonic acid strip membrane obtained in S2); stir at 50-60°C until completely dispersed, and ultrasonicate for 5-15 min to prepare an ATP-X / SPEEK or ATP-X / PFSA mixed solution; S33. Pour the ATP-X composite polymer mixed solution (ATP-X / SPEEK or ATP-X / PFSA) obtained in S32 onto a glass plate and dry it at 70-80°C for 12-24 hours, and then dry it at 100-120°C for 5-12 hours to obtain a polymer composite membrane containing ATP-X. The content of ATP-X in the composite membrane is 1-5 wt %, and the thickness of the obtained polymer composite membrane ranges from 50 to 120 μm.

[0050] Example 1 Step 1, preparation of ATP-H + Materials, specific steps are as follows: S11, weigh 10 g of attapulgite and add it to 250 ml of 1.0 M sulfuric acid solution, and stir magnetically at room temperature for 24 h to form a suspension; S12. Centrifuge the suspension obtained in S11 at 8000 rad / min and wash it alternately with ultrapure water and ethanol until the supernatant is neutral. Pour out the supernatant and the precipitate below is the protonated ATP.

[0051] S13, remove the protonated ATP layer, place it in a vacuum drying oven to dry, and ball mill the dried hydrogen ionized ATP at a speed of 400 rad / min for 20 min. After sieving with a sieve, ATP-H + Material.

[0052] Step S2, preparing SPEEK fiber, the specific steps are as follows: S21, sulfonating PEEK powder with 98 wt% concentrated sulfuric acid at a mass volume ratio of PEEK powder to concentrated sulfuric acid of 1:13 g / mL, stirring at 700 rpm for 65 min at 60°C to obtain a reddish-brown mixed solution of concentrated sulfuric acid and sulfonated polyetheretherketone; S22, slowly pouring the reacted solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing the SPEEK fiber with deionized water until neutral, drying the fiber in the shade at room temperature, and then drying the fiber in an oven to obtain dry SPEEK fiber. In this example, the degree of sulfonation of the SPEEK fiber was determined to be 55%.

[0053] Step S3, preparing a polymer composite membrane containing ATP-X, the specific steps are as follows: S31, taking 1.6 g of the SPEEK fiber dried in step S32, adding it to the dimethyl sulfoxide solution, with the mass volume ratio of the SPEEK fiber to the dimethyl sulfoxide solution being 1:32 g / mL, and then stirring under heating at 60°C until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, take 0.048 g of ATP-H obtained in step S13 + The material was added to the SPEEK dimethyl sulfoxide diaphragm casting solution of S31, stirred at 60 °C until completely dispersed, and then ultrasonically treated for 10 min to prepare ATP-H + / SPEEK mixed solution; S33, the ATP-H obtained in S32 + The mixed solution of ATP-H was poured onto a glass plate and dried at 75 °C for 12 h and then at 100 °C for 10 h to obtain ATP-H. + / SPEEK polymer composite diaphragm.

[0054] In this embodiment, ATP-H + / SPEEK polymer composite diaphragm thickness is 65 μm, ATP-H + The content of ATP-H is 3 wt%, and the composite membrane has uniform and dense texture and no ATP-H + The particles dissolve and have good mechanical properties.

[0055] The ATP-H obtained in this example + / SPEEK polymer composite membrane was assembled into an all-vanadium redox flow battery for testing and compared with an all-vanadium redox flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are shown in Figure 2. Figure 4 As shown in (a), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7 As shown in (a), the ATP-H prepared in this example + / SPEEK composite diaphragm is used in all-vanadium liquid flow batteries. The battery has a capacity retention rate of 62.1% after 100 cycles, a coulombic efficiency of 98.75%, and an energy efficiency of 84.01%.

[0056] The ATP-H obtained in this example + / SPEEK polymer composite membrane was assembled into a vanadium titanium redox flow battery for testing and compared with a vanadium titanium redox flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are shown in Figure 2. Figure 4 As shown in (c), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7 As shown in (c), the ATP-H prepared in this example + / SPEEK composite diaphragm is used in vanadium-titanium liquid flow batteries. After 100 charge and discharge cycles, the battery's capacity retention rate is 63.2%, the coulombic efficiency is 99.8%, and the energy efficiency is 81.2%.

[0057] Example 2 The difference from Example 1 is that: S2, preparation of perfluorosulfonic acid membrane without SPEEK fiber: Replace S2 with: Select perfluorosulfonic acid as the base membrane, fully acid-wash the recovered Nafion212 membrane, wash it with ultrapure water, dry it, and cut it into strips to obtain a strip-shaped perfluorosulfonic acid membrane; S31: Take 1.86 g of a strip of perfluorosulfonic acid membrane and add it to a dimethylacetamide solution at a mass volume ratio of 1:27 g / mL. Then, heat and stir at 60°C until a PFSA dimethylacetamide membrane casting solution with no solid residue is obtained. S32, take 0.0558 g ATP-H + Add it to the PFSA dimethylacetamide diaphragm casting solution, stir it at 60℃ until it is completely dispersed, and then ultrasonicate it for 10 minutes to remove bubbles to obtain ATP-H + / PFSA mixed solution; S33, the ATP-H obtained in S32 + The ATP-H / PFSA mixed solution was poured onto a glass plate and dried at 80 °C for 12 h and then at 120 °C for 5 h to obtain ATP-H + / PFSA polymer composite membrane.

[0058] The rest are the same as in Example 1.

[0059] The ATP-H obtained in this example +The thickness of the / PFSA polymer composite membrane is 52 μm, and the ATP-H + The content of ATP-H is 3wt%, the composite membrane has uniform and dense texture, and no ATP-H + The particle dissolution phenomenon is observed, and the material has good mechanical properties. It is tested in an all-vanadium liquid flow battery and compared with an all-vanadium liquid flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are shown in Figure 2. Figure 4 As shown in (b), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7 As shown in (b), the ATP-H + / PFSA polymer composite diaphragm is used in all-vanadium liquid flow batteries. After 100 charge and discharge cycles, the battery's capacity retention rate is 61.2%, the coulombic efficiency is 98.5%, and the energy efficiency is 82.3%.

[0060] The ATP-H obtained in this example + The PFSA polymer composite membrane was assembled into a vanadium-titanium flow battery for testing and compared with a vanadium-titanium flow battery equipped with a Nafion 212 membrane. The charge and discharge test curves are shown in Figure 2. Figure 4 As shown in (d), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7 As shown in (d), the ATP-H + / SPEEK polymer composite diaphragm is used in vanadium-titanium liquid flow batteries. After 100 charge and discharge cycles, the battery's capacity retention rate is 56.7%, the coulombic efficiency is 99.7%, and the energy efficiency is 80.1%.

[0061] Example 3 Step S1, preparation of ATP-K + Materials, specific steps are as follows: S11, weigh 5 g of attapulgite and add it to 250 ml of 0.5 M potassium chloride solution. Stir magnetically at room temperature for 20 h to form a suspension. After standing, take the supernatant and add sodium hydroxide solution to it to observe whether precipitation occurs. If precipitation occurs, add fresh 0.5 M potassium chloride solution and repeat the above steps until no precipitation is produced when sodium hydroxide is added to the supernatant. S12, centrifuging the suspension obtained in S11 at 7000 rad / min, and washing with ultrapure water and ethanol alternately until the supernatant is neutral, pouring out the supernatant, and the precipitate below is potassium ionized ATP; S13, the potassium ionized ATP was placed in a vacuum drying oven for drying, and after drying, the ATP was ball-milled at a speed of 400 rad / min for 20 min, and then sieved with a sieve to obtain ATP-K + Material.

[0062] Step S2, preparing SPEEK fiber, the specific steps are as follows: S21, sulfonating PEEK powder with 98 wt% concentrated sulfuric acid at a mass volume ratio of PEEK powder to concentrated sulfuric acid of 1:13 g / mL, stirring at 700 rpm at 60°C for 75 min to obtain a reddish-brown mixed solution of concentrated sulfuric acid and sulfonated polyetheretherketone; S22, slowly pouring the reddish-brown mixed solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing with deionized water until neutral, drying in the shade at room temperature, and then drying in an oven to obtain dry SPEEK fiber. In this example, the sulfonation degree of SPEEK is determined to be 60%; S23, ionizing the obtained dried SPEEK with a KOH solution, then immersing and washing it in deionized water until it becomes neutral, drying it in the shade at room temperature, and then drying it to obtain potassium-ionized SPEEK.

[0063] Step S3, preparing a polymer composite membrane containing ATP-X, the specific steps are as follows: S31, taking 1.65 g of SPEEK fiber ionized with potassium in step S23 and adding it to the dimethyl sulfoxide solution, with the mass volume ratio of SPEEK fiber to dimethyl sulfoxide solution being 1:32 g / mL, and then stirring under heating at 55° C. until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, take 0.0495 g ATP-K + Join SPEEK-K + The ATP-K was prepared by stirring in dimethyl sulfoxide membrane casting solution at 55 °C until it was completely dispersed and then ultrasonically treated for 10 min. + / SPEEK mixed solution; S33, the ATP-K obtained in S32 + The mixed solution of ATP-K was poured onto a glass plate and dried at 80 °C for 18 h and then at 120 °C for 5 h to obtain ATP-K. + / SPEEK polymer composite diaphragm.

[0064] In this embodiment, the modified attapulgite material still maintains a good tubular structure, as shown in the SEM image. Figure 11 As shown in the TEM image Figure 18 As shown in the figure, potassium ions can be clearly seen from the energy spectrum, indicating that potassium ionization was successful and the prepared ATP-K + / SPEEK polymer composite diaphragm thickness is 65 μm, ATP-K + The content is 3wt%. Figure 3As shown, the composite ion exchange membrane has uniform texture, ATP-K + The particles are evenly distributed in the diaphragm without dissolution. They are assembled into an iron-sulfur flow battery for testing and compared with an iron-sulfur flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are as follows: Figure 4 As shown in (e), the comparison of the efficiency of the long cycle is as follows Figure 8 As shown in (a), the peak power density comparison results are as follows Figure 10 As shown, the ATP-K prepared in this embodiment + / SPEEK polymer composite diaphragm is used in iron-sulfur liquid flow batteries. After 2700 charge and discharge cycles, the battery's capacity retention rate is 88.9%, the coulombic efficiency is 99.9%, and the energy efficiency is 82.7%.

[0065] In this embodiment, the -2 Compared with ATP-K + The energy efficiency and rate comparison of the battery assembled with SPEEK polymer composite membrane and Nafion 212 membrane are shown in the figure below. Figure 9 As shown in the figure, the polymer composite membrane has higher energy efficiency at different current densities, indicating that the polymer composite membrane has faster ion transmission capability.

[0066] Example 4 The difference from Example 3 is that: S2 does not prepare SPEEK fiber, but prepares perfluorosulfonic acid membrane: Replace S21-S22 with the following: fully pickle the used Nafion212 membrane with sulfuric acid, then wash it with ultrapure water, dry it, and cut it into strips to obtain a strip-shaped perfluorosulfonic acid membrane; S23, ionizing the strip of perfluorosulfonic acid membrane with a KOH solution, then immersing and washing it in deionized water until it becomes neutral, and then drying it in the shade at room temperature (25°C) to obtain a potassium-ionized strip of perfluorosulfonic acid membrane; S31: Take 1.9 g of potassium-ionized perfluorosulfonic acid (PFSA) strip membrane and add it to a dimethylacetamide solution at a mass volume ratio of PFSA to dimethylacetamide of 1:27 g / mL. Then, heat and stir at 55°C until a PFSA dimethylacetamide membrane casting solution with no solid residue is obtained. S32, take 0.038 g ATP-K + Add PFSA dimethylacetamide into the diaphragm casting solution, stir at 55℃ until completely dispersed, and then ultrasonicate for 15min to make ATP-K + Fully dispersed in the organic casting solution to obtain ATP-K + / PFSA mixed solution; S33, the ATP-K obtained in S32 + The ATP-K / PFSA mixed solution was poured onto a clean glass plate and dried at 75 °C for 18 h and then at 120 °C for 7 h to obtain ATP-K + / PFSA polymer composite membrane.

[0067] The rest are the same as in Example 3.

[0068] The ATP-K obtained in this example + / PFSA-K + The thickness of the polymer composite membrane is 54 μm, and the ATP-K + The content of ATP-K is 2wt%, the composite membrane has uniform and dense texture, and no ATP-K + The particles dissolve and have good mechanical properties. They are installed in an iron-sulfur flow battery for electrochemical testing and compared with an iron-sulfur flow battery equipped with a Nafion 212 diaphragm. The charge and discharge test curves are as follows: Figure 4 As shown in (f), the comparison of the efficiency of long cycle is as follows Figure 8 As shown in (b), the ATP-K prepared in this example + / PFSA-K + The polymer composite diaphragm is used in iron-sulfur liquid flow batteries. After 2,700 charge and discharge cycles, the battery's capacity retention rate is 88.1%, the coulombic efficiency is 99.75%, and the energy efficiency is 78%.

[0069] Example 5 S1, preparation of ATP-Na + Materials, specific steps are as follows: S11, weigh 10 g of attapulgite, add it to 250 ml of 1.0 M sodium chloride solution, and stir magnetically at room temperature for 24 h to form a suspension. After standing, take the supernatant and add sodium hydroxide solution to observe whether precipitation occurs. If precipitation occurs, add freshly prepared 1.0 M sodium chloride solution and repeat the above steps until no precipitation is produced when sodium hydroxide is added to the supernatant. S12, centrifuge the suspension obtained in S11 at 8000 rad / min, and wash it alternately with ultrapure water and ethanol until the supernatant is neutral. Pour off the supernatant, and the lower layer is the sodium ionized ATP; S13, remove the sodium ionized ATP from the bottom layer, place it in a vacuum drying oven to dry, and then ball mill it at a speed of 400 rad / min for 20 min, and then sieve it with a sieve to obtain ATP-Na + Material.

[0070] Step S2, preparing SPEEK fiber, the specific steps are as follows: S21, sulfonating PEEK powder with 98 wt% concentrated sulfuric acid at a mass volume ratio of 1:14 g / mL, stirring at 800 rpm at 55°C for 78 min to obtain a reddish-brown mixed solution of concentrated sulfuric acid and sulfonated polyetheretherketone; S22, slowly pouring the reddish-brown mixed solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing with deionized water until neutral, drying in the shade at room temperature, and then drying in an oven to obtain dry SPEEK fiber. In this example, the sulfonation degree of SPEEK was determined to be 61%; S23, ionizing the obtained dried SPEEK with a NaOH solution, then immersing and washing it in deionized water until it becomes neutral, drying it in the shade at room temperature, and then drying it to obtain sodium-ionized SPEEK; Step S3, preparing a polymer composite membrane containing ATP-X, the specific steps are as follows: S31, taking 1.65 g of the sodium-ionized SPEEK obtained in step S23, adding it to dimethyl sulfoxide, with the mass-to-volume ratio of SPEEK fiber to dimethyl sulfoxide being 1:25 g / mL, and then stirring under heating at 60° C. until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, take 0.0495 g ATP-Na + Add it to the SPEEK dimethyl sulfoxide diaphragm casting solution of S31, stir it at 60℃ until it is completely dispersed, and then ultrasonicate it for 15 minutes to prepare ATP-Na + / SPEEK mixed solution; S33, the ATP-Na obtained in S32 + The mixed solution of ATP-Na was poured onto a glass plate and dried at 80 °C for 12 h and then at 110 °C for 5 h to obtain the ATP-Na + / SPEEK polymer composite diaphragm.

[0071] The ATP-Na obtained in this example + / SPEEK polymer composite membrane thickness is 65 μm, ATP-Na + The content is 3wt%, the composite ion exchange membrane has uniform texture and no ATP-Na + The particle dissolution phenomenon was observed and electrochemical tests were carried out in a zinc-iron flow battery. The charge and discharge test curves were compared with those of a zinc-iron flow battery equipped with a Nafion 212 membrane. Figure 4 As shown in (g), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7 As shown in (e), the ATP-Na + / SPEEK-Na+ The polymer composite diaphragm is used in zinc-iron liquid flow batteries. After 10,000 cycles, the capacity retention rate of the battery is 58.7%, the coulombic efficiency is 99.9%, and the energy efficiency is 84.3%.

[0072] Example 6 The difference from Example 5 is that: SPEEK fiber is not prepared, and perfluorosulfonic acid membrane is prepared: Replace S21-S22 with: fully pickle the used Nafion212 membrane with sulfuric acid, then wash it with ultrapure water, dry it, and cut it into strips to obtain a strip-shaped perfluorosulfonic acid membrane; S23, ionizing the strip of perfluorosulfonic acid membrane with a NaOH solution, then immersing and washing the strip in deionized water until neutral, and drying the strip in the shade at room temperature to obtain a sodium-ionized perfluorosulfonic acid membrane; S31, take 1.90g of the cut sodium ionized strip perfluorosulfonic acid membrane and add it to the dimethylacetamide solution. + The mass volume ratio of PFSA and dimethylacetamide is 1:26 g / mL, and then stirred at 60 °C until a PFSA dimethylacetamide diaphragm casting solution with no solid phase residue is obtained; S32, take 0.057 g ATP-Na + Add it to the PFSA dimethylacetamide diaphragm casting solution, stir it at 60℃ until it is completely dispersed, and then ultrasonicate it for 10 minutes to prepare ATP-Na + / PFSA mixed solution; S33, the ATP-Na obtained in S32 + The ATP-Na / PFSA mixed solution was dried at 80 °C for 12 h and then at 110 °C for 10 h to obtain + / PFSA polymer composite membrane.

[0073] The rest are the same as in Example 5.

[0074] In this embodiment, the ATP-Na + / PFSA polymer composite membrane thickness is 54 μm, ATP-Na + The content of ATP-Na is 3wt%, the composite membrane has uniform and dense texture, and no ATP-Na + The particle dissolution phenomenon and good mechanical properties were observed. The zinc-iron liquid flow battery was tested and compared with the zinc-iron liquid flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are shown in Figure 2. Figure 4 As shown in (h), the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5 to 7As shown in (f), the ATP-Na + / PFSA-Na + The polymer composite diaphragm is used in zinc-iron redox flow batteries. After 10,000 cycles, the capacity retention rate of the battery is 72.4%, the coulombic efficiency is 99.9%, and the energy efficiency is 89.3%.

[0075] Example 7 The difference from Example 3 is that: In S13, the ball milling speed was 300 rad / min and the ball milling time was 15 min; In S32, 0.0165 g of ATP-K was added when preparing the composite membrane. + .

[0076] The rest are the same as in Example 3.

[0077] The ATP-K obtained in this example + / SPEEK-K + The thickness of the polymer composite membrane is 63 μm, and the ATP-K + The content is 1wt%, such as Figure 15 As shown, ATP-K + After the content of ATP-K is reduced, the ATP-K + The membrane was assembled into an iron-sulfur flow battery for testing and compared with an iron-sulfur flow battery equipped with a Nafion 212 membrane. In this example, the ATP-K + / SPEEK-K + The coulombic efficiency and capacity retention rate of polymer composite membranes used in iron-sulfur liquid flow batteries are shown in the figure. Figure 13 As shown in (c), the capacity retention rate of the battery after 1500 cycles is 92.4%, the coulombic efficiency is 99.8%, and the energy efficiency is 86.7%.

[0078] The capacity efficiency and coulombic efficiency of this embodiment are still relatively stable, and the ATP-K + The addition amount will not have a significant impact on the selectivity of the diaphragm.

[0079] Example 8 S1, preparation of ATP-Na + Materials, specific steps are as follows: S11, weigh 1 g of attapulgite and add it to 250 ml of 0.1 M sodium chloride solution. Stir magnetically at room temperature for 12 h to form a suspension. After standing, take the supernatant and add sodium hydroxide solution to observe whether precipitation occurs. If precipitation occurs, add freshly prepared 0.1 M sodium chloride solution and repeat the above steps until no precipitation is produced when sodium hydroxide is added to the supernatant. S12, centrifuge the suspension obtained in S11 at 6000 rad / min, and wash it alternately with ultrapure water and ethanol until the supernatant is neutral. Pour off the supernatant, and the lower layer is the sodium ionized ATP; S13, take the sodium ionized ATP from the bottom layer and dry it in a vacuum drying oven. After drying, ball mill it at a speed of 200 rad / min for 10 min, and then sieve it with a sieve to obtain ATP-Na + Material; Step S2, preparing SPEEK fiber, the specific steps are as follows: S21, sulfonating PEEK powder with 98 wt% concentrated sulfuric acid at a mass volume ratio of PEEK powder to concentrated sulfuric acid of 1:15 g / mL, stirring at 900 rpm for 80 min at 50° C. to obtain a reddish-brown mixed solution of concentrated sulfuric acid and sulfonated polyetheretherketone; S22, slowly pouring the reddish-brown mixed solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing with deionized water until neutral, drying in the shade at room temperature, and then drying in an oven to obtain dry SPEEK fiber. In this example, the sulfonation degree of SPEEK was determined to be 65%; S23, ionizing the obtained dried SPEEK with a NaOH solution, then immersing and washing it in deionized water until it becomes neutral, drying it in the shade at room temperature, and then drying it to obtain sodium-ionized SPEEK.

[0080] Step S3, preparing a polymer composite membrane containing ATP-X, the specific steps are as follows: S31, taking 2.95 g of the sodium-ionized SPEEK obtained in step S23, adding it to the dimethyl sulfoxide solution, with the mass-to-volume ratio of SPEEK fiber to dimethyl sulfoxide being 1:17 g / mL, and then stirring under heating at 50° C. until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, take 0.1475 g ATP-Na + Add it to the SPEEK dimethyl sulfoxide diaphragm casting solution of S31, stir it at 50℃ until it is completely dispersed, and then ultrasonicate it for 5 minutes to prepare ATP-Na + / SPEEK mixed solution; S33, the ATP-Na obtained in S32 + The mixed solution of / SPEEK was poured onto a glass plate and dried at 70℃ for 24h and then at 100℃ for 12h to obtain ATP-Na + / SPEEK polymer composite diaphragm.

[0081] The ATP-Na obtained in this example+ / SPEEK polymer composite membrane thickness is 120 μm, ATP-Na + The content is 5%, the composite ion exchange membrane has uniform texture and no ATP-Na + The particle dissolution phenomenon was observed and electrochemical tests were carried out in a zinc-iron flow battery. The charge and discharge test curves were compared with those of a zinc-iron flow battery equipped with a Nafion 212 membrane. Figure 19 As shown in the figure, the comparison results of capacity retention rate, coulombic efficiency and energy efficiency are shown in the figure. Figure 20 to Figure 22 As shown, the ATP-Na prepared in this embodiment + / SPEEK polymer composite diaphragm is used in zinc-iron liquid flow batteries. After 14,000 cycles, the capacity retention rate is 68.7%, the coulombic efficiency is 99.8%, and the energy efficiency is 79.8%. By increasing the amount of sulfonated polyetheretherketone matrix to increase the thickness of the diaphragm and adding modified attapulgite, more ion transmission channels can be provided, thereby improving the ion selectivity compared with the Nafion212 diaphragm.

[0082] Example 9 The difference from Example 8 is that: SPEEK fiber is not prepared, and perfluorosulfonic acid membrane is prepared: Replace S21-S22 with: fully pickle the used Nafion212 membrane with sulfuric acid, then wash it with ultrapure water, dry it, and cut it into strips to obtain a strip-shaped perfluorosulfonic acid membrane; S23, ionizing the strip of perfluorosulfonic acid membrane with a NaOH solution, then soaking and washing it with deionized water until it becomes neutral, drying it in the shade at room temperature, and then drying it to obtain a sodium-ionized strip of perfluorosulfonic acid membrane; S31, take 1.78g of sodium ionized strip perfluorosulfonic acid membrane and add it to dimethylacetamide solution, PFSA-Na + The mass volume ratio of PFSA and dimethylacetamide is 1:28 g / mL, and then stirred at 50°C until a PFSA dimethylacetamide diaphragm casting solution with no solid phase residue is obtained; S32, take 0.0178 g ATP-Na + Add it to the PFSA dimethylacetamide diaphragm casting solution, stir it at 50℃ until it is completely dispersed, and then ultrasonicate it for 5 minutes to prepare ATP-Na + / PFSA mixed solution; S33, the ATP-Na obtained in S32 + The / PFSA mixed solution was dried at 70 °C for 12 h and then at 100 °C for 24 h to obtain ATP-Na + / PFSA polymer composite membrane.

[0083] The rest is the same as in Example 8.

[0084] In this embodiment, the ATP-Na + / PFSA polymer composite membrane thickness is 50 μm, ATP-Na + The content of 1wt% is uniform and dense, and there is no ATP-Na + The particles dissolve and have good mechanical properties. They are tested in a zinc-iron flow battery and compared with a zinc-iron flow battery equipped with Nafion 212 membrane. The charge and discharge test curves are as follows: Figure 23 As shown in the figure, the comparison results of capacity retention rate, coulombic efficiency and energy efficiency are shown in the figure. Figures 24 to 26 As shown in FIG, the ATP-Na prepared in this embodiment + A PFSA / PFSA polymer composite separator used in zinc-iron flow batteries achieved a capacity retention rate of 43.6%, a coulombic efficiency of 99.7%, and an energy efficiency of 71.5% after 10,000 cycles. The separator is thinner due to the reduced perfluorosulfonic acid matrix, requiring less modified attapulgite.

[0085] Example 10 The difference from Example 4 is that: In S13, the ball milling speed was 300 rad / min and the ball milling time was 15 min.

[0086] The rest are the same as in Example 4.

[0087] The ATP-K obtained in this example + / PFSA-K + Polymer composite diaphragm is used in iron-sulfur liquid flow battery, and the long cycle efficiency comparison chart is as follows Figure 8 As shown in (e), after 2000 charge and discharge cycles, the battery's capacity retention rate is 90.70%, the coulombic efficiency is 99.83%, and the energy efficiency is 74.34%.

[0088] Comparative Example 1 The difference from Example 3 is that: The stirring time in S21 is 55 min; The degree of sulfonation of SPEEK was determined to be 50% in S22.

[0089] The rest are the same as in Example 3.

[0090] The ATP-K obtained in this comparative example + / SPEEK polymer composite membrane (sulfonation degree of 50%) was assembled into an iron-sulfur liquid flow battery for testing. The capacity and voltage comparison of the composite membranes with sulfonation degrees of 50% and 60% assembled into the battery are shown in the figure below. Figure 16As shown in the figure, it can be seen that there is a large polarization in the internal resistance of the battery. The diaphragm prepared in this comparative example is compared with the iron-sulfur liquid flow battery equipped with Nafion 212 membrane. The long cycle efficiency of the two is as follows: Figure 8 As shown in (c), the battery capacity is maintained at 32.7% after 300 cycles, the energy efficiency is low, only 34.6%, and the coulombic efficiency is 99.0%.

[0091] Comparative Example 2 The difference from Example 3 is that: The stirring time in S21 is 85 min; The degree of sulfonation of SPEEK was determined to be 67% in S22.

[0092] The rest are the same as in Example 3.

[0093] The ATP-K obtained in this comparative example + / SPEEK polymer composite membrane (sulfonation degree 67%) was assembled into an iron-sulfur liquid flow battery for testing and compared with an iron-sulfur liquid flow battery equipped with Nafion 212 membrane. The long-cycle comparison of the two is shown in the figure Figure 8 As shown in (d), the capacity retention after 1000 cycles is 54.8%, the energy efficiency is 43.8%, and the coulombic efficiency is 99.8%. The capacity retention rate is much lower than the 90.4% capacity retention rate of Nafion212 after 1000 cycles. The capacity retention rate comparison of SPEEK with a sulfonation degree of 67% and SPEEK with a sulfonation degree of 60% is shown in the figure below. Figure 17 As shown by Figure 17 It can be clearly seen that excessive sulfonation will reduce the capacity retention rate, affect the normal operation of the battery, and reduce energy efficiency.

[0094] Comparative Example 3 The difference from Example 3 is that the ball milling speed in S13 is 550 rad / min and the ball milling time is 40 min.

[0095] The rest are the same as in Example 3.

[0096] like Figure 12 As shown, in this embodiment, the morphology of ATP changes after the ball milling time increases, and the excellent one-dimensional tubular structure is lost and the ATP aggregates into irregular spheres.

[0097] The ATP-K obtained in this comparative example + / SPEEK polymer composite membrane was assembled into an iron-sulfur flow battery for testing and compared with an iron-sulfur flow battery equipped with Nafion 212 membrane. The ATP-K prepared in this comparative example + / SPEEK polymer composite diaphragm is used in iron-sulfur liquid flow battery, coulombic efficiency and capacity retention rate are shown in the figure Figure 13 As shown in (a), the capacity retention rate of the battery after 1000 cycles is 19.7%, the coulombic efficiency is 99.6%, and the energy efficiency is 76.5%.

[0098] The capacity of this comparative example decays quickly and the coulombic efficiency is unstable, which greatly affects the barrier effect of the diaphragm on the active material and damages the cycle life of the liquid flow battery.

[0099] Comparative Example 4 The difference from Example 3 is that 0.099 g of ATP-K was added when preparing the composite membrane in S32. + , that is, ATP-K in the composite membrane + The content is 6 wt%, The rest are the same as in Example 3.

[0100] The ATP-K obtained in this comparative example + / SPEEK-K + The polymer composite membrane was assembled into an iron-sulfur liquid flow battery for testing. The coulombic efficiency and capacity retention rate of this comparative example are shown in the figure below. Figure 13 As shown in (b), the capacity of the battery dropped sharply after 520 cycles. At 531 cycles, the capacity retention rate was 17.5%, the coulombic efficiency was 69.3%, and the energy efficiency was 47.5%.

[0101] The XRD patterns of the attapulgite before and after modification and the composite films with different addition percentages are shown in Figure 2. Figure 2 As shown in the figure, it can be seen that with the increase of the addition amount, the attapulgite is no longer dispersed in the microphase aggregation of the diaphragm, and shows the characteristic peak of the attapulgite. Excessive addition of attapulgite is not conducive to the barrier of active substances. The diaphragm with increased attapulgite content is as follows Figure 14 As shown, it can be seen that the aggregation caused by excessive doping seriously affects the battery performance.

[0102] Comparative Example 5 The difference from Example 3 is that the ball milling speed in S13 is 100 rad / min and the ball milling time is 5 min.

[0103] The rest are the same as in Example 3.

[0104] The diaphragm obtained in this comparative example has a too short ball milling time, resulting in the attapulgite being too large in size and unable to be sieved well. It cannot be dispersed well when directly added to the diaphragm casting liquid, and there is local uneven dispersion. After assembling the iron-sulfur liquid flow battery, the active material is quickly cross-contaminated and the battery cannot operate normally.

[0105] Comparative Example 6 The difference from Example 4 is that the ball milling time in S13 is 5 h.

[0106] The rest are the same as in Example 4.

[0107] The diaphragm obtained in this comparative example has the same problem as comparative example 3 due to the long ball milling time. The morphology has changed and become spherical. The attapulgite cannot be well compounded with the diaphragm. It is easy to fall off from the surface of the diaphragm during the cycle, and leaves uneven holes, which greatly reduces the hindering effect on the active substance and the battery cannot operate normally.

[0108] Comparative Example 7 The difference from Example 3 is that 3g of potassium ionized SPEEK fiber is taken in S31, and 0.015g of ATP-K is taken in S32. + .

[0109] The rest are the same as in Example 3.

[0110] The ATP-K prepared in this comparative example + / SPEEK-K + ATP-K in polymer composite membrane + The content of ATP-K is 0.5wt%, the thickness of the membrane is 110μm, and the ATP-K + / SPEEK-K + Polymer composite diaphragms are used in iron-sulfur liquid flow batteries. Due to the excessive thickness of the diaphragm, the internal resistance of the assembled iron-sulfur liquid flow battery is too large, and the voltage drop is too large during charge and discharge tests. The charge and discharge test cannot be carried out well within the charge and discharge range of 0.4~1.4V of the iron-sulfur battery. The battery energy efficiency is low and it fails quickly.

[0111] Comparative Example 8 The difference from Example 3 is that: 0.5 g of attapulgite is taken in S11, the mass volume ratio of PEEK and concentrated sulfuric acid in S21 is 1:10 g / mL, the stirring temperature is 40°C, and the mass volume ratio of SPEEK fiber and dimethyl sulfoxide solution in S31 is 1:15 g / mL, and the stirring temperature is 30°C.

[0112] The rest are the same as in Example 3.

[0113] In this comparative example, the dimethyl sulfoxide solution ratio is too low and the dissolution temperature is too low. The time to dissolve into a clear and transparent casting solution is too long. In addition, due to the adjustment of the parameters in S21, the sulfonation degree is too low. The prepared diaphragm has the problems of uneven matrix dissolution and poor ion conductivity. + / SPEEK-K polymer composite diaphragm is used in iron-sulfur liquid flow batteries. During the charge and discharge cycle, the concentration of sulfonic acid groups used for ion exchange is low due to the decrease in sulfonation degree, resulting in low energy efficiency. In addition, due to uneven dissolution, the diaphragm thickness is uneven and the mechanical strength is reduced, which soon leads to obvious cross-contamination.

[0114] Comparative Example 9 The difference from Example 3 is that: 15 g of attapulgite is taken in S11, the mass volume ratio of PEEK and concentrated sulfuric acid in S21 is 1:18 g / mL, the stirring temperature is 80°C, and the mass volume ratio of SPEEK fiber and dimethyl sulfoxide solution in S31 is 1:35 g / mL, and the stirring temperature is 75°C.

[0115] The rest are the same as in Example 3.

[0116] In this comparative example, the proportion of concentrated sulfuric acid was increased and the reaction time was increased. Under the same sulfonation reaction time, the obtained PEEK chain had too many sulfonic acid groups and was too hydrophilic. It was difficult to form fibers in ice water and was in the form of jelly gel. A small amount of SPEEK that could still be in the form of fibers was dried and tested to have a sulfonation degree of 80%. ATP-K was prepared under the conditions of S31. + / SPEEK-K + The polymer composite diaphragm, when used in iron-sulfur liquid flow batteries, partially dissolves after several cycles of charge and discharge, which obviously causes the positive and negative electrolytes to react, and the barrier function of the diaphragm fails, which in turn leads to battery failure.

[0117] Comparative Example 10 The difference from Example 4 is that 2.5 g of potassium ionized perfluorosulfonic acid strip membrane is taken in S31, and 0.02 g of ATP-K is taken in S32. + .

[0118] The rest are the same as in Example 4.

[0119] The ATP-K obtained in this comparative example + / PFSA-K + ATP-K in polymer composite membrane + The content of is 0.8wt%, the thickness of the diaphragm is 70 μm, and the polymer composite diaphragm obtained in this comparative example is used in iron-sulfur liquid flow battery. The long cycle efficiency comparison is shown in the figure below. Figure 8 As shown in (f), the battery has a capacity retention rate of 85.00%, a coulombic efficiency of 99.91%, and an energy efficiency of 71.84% after 1500 cycles of charge and discharge. +The percentage of content is reduced, and the test effect of this comparative example is not as good as that of Nafion212 membrane. The increase in thickness is caused by the increase in the amount of perfluorosulfonic acid matrix used, which will further increase the preparation cost of the composite membrane.

[0120] Comparative Example 11 The difference from Example 4 is that 1.7 g of potassium ionized strip perfluorosulfonic acid membrane is taken in S31, and 0.085 g of ATP-K is taken in S32. + .

[0121] The rest are the same as in Example 4.

[0122] The ATP-K obtained in this comparative example + / PFSA-K + ATP-K in polymer composite membrane + The content of is 5wt%, the thickness of the composite diaphragm is 47 μm, and the polymer composite diaphragm obtained in this comparative example is used in iron-sulfur liquid flow battery. The long cycle efficiency comparison is shown in the figure below. Figure 8 As shown in (g), the battery has a capacity retention rate of 26.80%, a coulombic efficiency of 99.8%, and an energy efficiency of 69.15% after 900 charge and discharge cycles. The reduction in the amount of the diaphragm matrix leads to a decrease in the thickness of the diaphragm and increases the ATP-K + With the addition of a certain amount, the energy efficiency is improved in the early stage of the charge and discharge test because the ion transmission path is shortened due to the reduction in the thickness of the diaphragm, but the stability of long-term operation is reduced, and the capacity and energy efficiency decay rapidly after 800 cycles.

[0123] Comparative Example 12 The difference from Example 4 is that in S31, the mass volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution is 1:20 g / mL, and the stirring is carried out at 30°C.

[0124] The rest are the same as in Example 4.

[0125] The polymer composite diaphragm obtained in this comparative example is used in iron-sulfur liquid flow batteries. Due to the low proportion and dissolution temperature of dimethylacetamide solution, it takes too long to dissolve into a clear and transparent casting solution. + / PFSA-K + Polymer composite diaphragms are used in iron-sulfur liquid flow batteries. During the charge and discharge cycle, due to uneven dissolution, uneven diaphragm thickness, and decreased mechanical strength, obvious cross-contamination soon occurred, leading to battery failure.

[0126] Comparative Example 13 The difference from Example 4 is that in S31, the mass volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution is 1:30 g / mL, and the stirring is carried out at 70°C.

[0127] The rest are the same as in Example 4.

[0128] The polymer composite diaphragm obtained in this comparative example is used in iron-sulfur liquid flow batteries. The long cycle efficiency comparison chart is as follows Figure 8 As shown in (h), after 1500 charge-discharge cycles, the battery's capacity retention was 28.44%, its Coulombic efficiency was 99.87%, and its energy efficiency was 62.13%. Increasing the proportion of dimethylacetamide solution, while maintaining the same drying time, can lead to residual organic solvent on the diaphragm. This increases the vapor pressure during stirring, which can lead to excessive pressure within the flask and cause the cork to fly out. This increases the preparation requirements and the cost of the diaphragm. When used in batteries, the resulting diaphragm also suffers from the effects of residual solvent, shortening the battery life.

[0129] The performance comparison of the composite diaphragms obtained in various embodiments and comparative examples and the batteries assembled therein is shown in Table 1: Table 1 Performance comparison of various examples and comparative examples

[0130] Due to the different types of active materials on both sides in different systems, the structure and molecular size of the active materials themselves greatly affect the life and efficiency of the battery. Iron-based liquid flow batteries have greater steric hindrance when passing through the diaphragm due to the large molecular volume of ferrocyanide, and the negative charge it carries is not easy to pass through the diaphragm under the influence of the Donan effect. Therefore, they are superior to vanadium-based liquid flow batteries in terms of life.

[0131] As can be seen from Comparative Examples 1 and 2, due to the decrease in the degree of sulfonation, the proportion of grafted sulfonic acid groups decreases, and the density of ion exchange groups used to exchange potassium ions after potassium ionization is low. Therefore, the ion exchange rate is limited, the internal resistance of the battery increases, and there is a large polarization, which is not conducive to the normal operation of the battery. For membranes with a high degree of sulfonation, the increase in the degree of sulfonation leads to an excessively high density of hydrophilic groups, resulting in severe swelling, which leads to the expansion of ion transmission channels and the reduction of the ability to prevent cross-contamination of active substances. Sulfur shuttling causes elemental sulfur to form a barrier layer to ion exchange on the membrane surface and the electrode surface, thereby reducing energy efficiency.

[0132] The thickness of the composite diaphragm of the present invention is maintained at 50~120μm. The thickness of the diaphragm will affect the barrier effect of the diaphragm on the positive and negative active materials and the length of the ion transmission channel, thereby affecting the ion transmission performance of the diaphragm. If the thickness of the diaphragm is too thin, the active materials on both sides cannot be well blocked and are easy to pass through the diaphragm to cause cross contamination. If the thickness of the diaphragm is too thick, it will have a certain hindering effect on the transmission of ions that play a conductive role in the supporting electrolyte, resulting in an increase in the internal resistance of the battery and a decrease in energy efficiency.

[0133] The attapulgite used in the present invention is used to increase the ion transmission channel and can accelerate ion transmission. As the content increases, the tubular transmission channels increase, but excessive amount will cause the channels to pile up and intertwine, resulting in larger transmission channels in the diaphragm, causing the diaphragm to lose its screening effect on the active substance, resulting in cross-contamination of the electrolyte.

[0134] It can be seen from Comparative Examples 3, 5, and 6 that a ball milling time that is too short is not conducive to the dispersion of the attapulgite, while a ball milling time that is too long will change the morphology of the attapulgite, resulting in the composite diaphragm failing to achieve the expected effect.

[0135] This invention modifies attapulgite, an inorganic material with a one-dimensional tubular structure and abundant reserves in my country, by protonating, potassium-ionizing, and sodium-ionizing it. Combined with pre-ionized SPEEK and PFSA matrices, this material is stably and efficiently applied in various flow battery systems, including all-vanadium, vanadium-titanium, iron-sulfur, and zinc-iron. Its suitable pore size and abundant exchangeable cations make the modified attapulgite well suited for these systems. The preparation process also explores the addition amount, ball milling time, and degree of sulfonation, determining the effective range of the invention. The simplest possible preparation method further reduces the cost of large-scale applications, providing a solution to the membrane problem in large-scale flow battery applications.

[0136] Each embodiment in this specification is described in a related manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiment is generally similar to the method embodiment, so the description is relatively simple. For related parts, refer to the description of the method embodiment.

[0137] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing an ATP polymer composite membrane for a flow battery, characterized in that: The preparation steps are as follows: Step S1, preparing ATP-X material: S11, adding attapulgite to a solution of sulfuric acid, potassium chloride or sodium chloride, and stirring at room temperature to form a suspension; S12, centrifuging the suspension obtained in S11 and washing it alternately with ultrapure water and ethanol until the supernatant is neutral after the last wash, pouring out the supernatant, and the precipitate below is ionized ATP-X; S13, removing the ionized ATP-X layer, drying, ball milling and sieving to obtain ATP-X material; Step S2, preparing SPEEK fiber or strip-shaped perfluorosulfonic acid membrane; Step S3, preparing a polymer composite membrane containing ATP-X.

2. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 1, wherein: The steps for preparing the SPEEK fibers described in S2 are as follows: S21, sulfonating the polyetheretherketone powder with concentrated sulfuric acid to obtain a reddish-brown mixed solution; S22, slowly pouring the reddish-brown mixed solution into a stirred ice-water mixture to obtain SPEEK fiber, and repeatedly washing with deionized water until neutral, and then drying in the shade at room temperature to obtain dry SPEEK fiber. For non-proton conducting liquid flow battery systems, proceed to S23, and for proton conducting liquid flow battery systems, directly proceed to S3; S23, ionizing the prepared SPEEK fiber with one of a KOH solution or a NaOH solution, then immersing and washing the fiber in deionized water until the fiber becomes neutral, and then drying the fiber in the shade at room temperature to obtain the ionized SPEEK fiber.

3. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 1, wherein: The steps for preparing the strip-shaped perfluorosulfonic acid membrane described in S2 are as follows: The recovered perfluorosulfonic acid proton exchange membrane is fully acid-washed with sulfuric acid, washed with ultrapure water and dried, and then cut into strips to obtain strip perfluorosulfonic acid membranes. For non-proton conductive flow battery systems, continue , proton-conducting flow battery system, directly conducts S3; The strip-shaped perfluorosulfonic acid membrane is ionized with one of a KOH solution or a NaOH solution, then immersed and cleaned in deionized water until neutral, and then dried in the shade at room temperature to obtain an ionized strip-shaped perfluorosulfonic acid membrane.

4. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 2, wherein: After the SPEEK fiber is prepared in S2, the preparation steps of S3 are as follows: S31, adding SPEEK fiber to the dimethyl sulfoxide solution and stirring continuously until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting solution is obtained; S32, adding ATP-X to the SPEEK dimethyl sulfoxide diaphragm casting solution of S31 to prepare an ATP-X / SPEEK mixed solution; S33, pouring the mixed solution obtained in S32 onto a glass plate, and drying it twice to obtain an ATP-X / SPEEK polymer composite membrane.

5. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 3, characterized in that: After the strip-shaped perfluorosulfonic acid membrane is prepared in S2, the preparation steps of S3 are as follows: , adding the strip-shaped perfluorosulfonic acid membrane into the dimethylacetamide solution and stirring continuously until a perfluorosulfonic acid dimethylacetamide diaphragm casting solution without solid phase residue is obtained; ATP-X was added to the perfluorosulfonic acid dimethylacetamide diaphragm casting solution, stirred until completely dispersed, and then ultrasonically treated to prepare an ATP-X / PFSA mixed solution; ,Will The obtained mixed solution was poured onto a glass plate and dried twice to obtain an ATP-X / PFSA polymer composite membrane.

6. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 1, characterized in that: The ATP-X material described in S1 is ATP-H + , ATP-K + or ATP-Na + , In S11, 1-10 g of attapulgite is taken, the solution concentration is 0.1-1.0 M, and the stirring time is 12-24 h; In the S12, the centrifugal speed is 6000-8000 rad / min; In the S13, the ball milling speed is 200-400 rad / min, and the ball milling time is 10-20 min.

7. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 2, characterized in that: In the S21, the mass volume ratio of polyetheretherketone powder to concentrated sulfuric acid is 1: (13-15) g / mL, and the mixture is stirred at 700-900 r / min at 50-60° C. for 65-80 min.

8. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 4, characterized in that: In the S31, the mass volume ratio of the SPEEK fiber and the dimethyl sulfoxide solution is 1: (17-32) g / mL, and the temperature during stirring is 50-60 °C; In the S32, ATP-X is maintained at 1-5 wt% of the SPEEK fiber, the stirring temperature is 50-60°C, and the ultrasonic time is 5-10 min; In the step S33, the product is first dried at 70-80° C. for 12-24 hours, and then dried at 100-120° C. for 5-12 hours.

9. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 5, characterized in that: described In the experiment, the mass volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution was 1:(26-28) g / mL, and the stirring temperature was 50-60 °C. described In the experiment, ATP-X was maintained at 1-3 wt% of the dried PFSA strip film, the stirring temperature was 50-60 °C, and the ultrasonic time was 5-10 min. described First dry at 70~80℃ for 12~24h, then dry at 100~120℃ for 5~12h.

10. The method for preparing an ATP polymer composite membrane for a flow battery according to claim 2, characterized in that: After the sulfonation reaction is completed, the sulfonation degree of the sulfonated polyetheretherketone is 55% to 65%.

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