Preparation method of ATP high-molecular composite diaphragm for liquid flow battery

Abstract

The application provides a preparation method of an ATP high-molecular composite diaphragm for a flow battery, which comprises the following steps: taking sulfonated polyether ether ketone or recycled perfluorosulfonic acid as a base film, preparing a high-molecular composite diaphragm containing ATP-X, wherein ATP-X is ATP-H + , ATP-K + or ATP-Na + , first preparing ATP-X material, then preparing a SPEEK fiber or a recycled perfluorosulfonic acid film, and finally preparing a high-molecular composite diaphragm, wherein the high-molecular composite diaphragm prepared by the application can realize long-time stable cyclic operation of the flow battery, and is not limited to a single flow battery system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid flow batteries, and particularly relates to a preparation method of an ATP high-molecular composite diaphragm for a liquid flow battery. BACKGROUND

[0002] In recent years, the new energy industry mainly based on photoelectricity and wind power has developed rapidly, but due to the geographical limitations, discontinuity and instability of wind power and photoelectricity, they cannot be well integrated into the power grid, while the liquid flow battery has good safety while playing a role in peak load shifting.

[0003] The diaphragm is one of the key materials of the liquid flow battery, has the functions of preventing the cross contamination of the positive and negative electrolytes and conducting ions to complete the circuit loop, and an ideal composite diaphragm needs to have the following characteristics: high proton conductivity, high ion selectivity, high chemical stability, low cost, etc. At present, the diaphragm material mainly used at home and abroad is the Nafion series film of the American DuPont Company, the raw material preparation of which is seriously polluting, ion penetration is serious, and the price is high, which limits the commercial application of the liquid flow battery in the large-scale energy storage field. For this reason, many researchers have made extensive research on the composite diaphragm for the liquid flow battery, although the performance of the diaphragm in some aspects has been effectively improved, but these diaphragms still have the shortcomings of high cost, poor comprehensive performance, complex preparation process and being unable to be applied to various liquid flow battery systems, etc., and cannot meet the requirements of the commercial application of the liquid flow battery. Therefore, to prepare a composite diaphragm with low cost, long service life, excellent comprehensive performance and being applicable to various systems to promote the large-scale application of the liquid flow battery is a problem to be solved at present. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of an ATP high-molecular composite diaphragm for a liquid flow battery, so as to realize the stable and long-time cyclic operation of the liquid flow battery and solve the problem in the prior art that the diaphragm can only be used for a single liquid flow battery system.

[0005] The technical scheme adopted by the present application is a preparation method of an ATP high-molecular composite diaphragm for a liquid flow battery, and the preparation steps are as follows:

[0006] Step S1, preparing ATP-X material:

[0007] S11, adding attapulgite to a solution of sulfuric acid, potassium chloride or sodium chloride, stirring at room temperature to form a suspension;

[0008] S12, performing centrifugation on the suspension obtained in S11, and alternately washing with ultrapure water and ethanol until the supernatant after the last washing is neutral, pouring out the supernatant, and the lower precipitate is ionized ATP-X;

[0009] S13, after the delaminated ATP-X is dried, ball milled and sieved, the ATP-X material is obtained;

[0010] Step S2, preparing SPEEK fiber or strip-like perfluorosulfonic acid membrane;

[0011] Step S3, preparing ATP-X-containing polymer composite diaphragm.

[0012] Further, the SPEEK fiber preparation step in S2 is as follows:

[0013] S21, sulfonating polyether ether ketone powder with concentrated sulfuric acid to obtain a red-brown mixed solution;

[0014] S22, slowly pour the red-brown mixed solution into the stirred ice-water mixture to obtain SPEEK fiber, and repeatedly wash with deionized water until neutral, then dry at room temperature and dry to obtain dry SPEEK fiber, for non-proton conducting flow battery system, continue to S23, and for proton conducting flow battery system, directly proceed to S3;

[0015] S23, ionize the prepared SPEEK fiber with one of KOH solution or NaOH solution, then soak and clean with deionized water until neutral, dry at room temperature, and dry to obtain ionized SPEEK fiber.

[0016] Further, the strip-like perfluorosulfonic acid membrane preparation step in S2 is as follows:

[0017] : After the recovered perfluorosulfonic acid proton exchange membrane is fully pickled with sulfuric acid, washed with ultrapure water and dried, it is cut into strips to obtain a strip-like perfluorosulfonic acid membrane, for non-proton conducting flow battery system, continue to , for proton conducting flow battery system, directly proceed to S3;

[0018] Ionize the strip-like perfluorosulfonic acid membrane with one of KOH solution or NaOH solution, then soak and clean with deionized water until neutral, dry at room temperature, and dry to obtain ionized strip-like perfluorosulfonic acid membrane.

[0019] Further, if SPEEK fiber is prepared in S2, the preparation step of S3 is as follows:

[0020] S31, add the SPEEK fiber to dimethyl sulfoxide solution and continuously stir until a clear and transparent SPEEK dimethyl sulfoxide diaphragm casting liquid is obtained;

[0021] S32, ATP-X is added to the SPEEK dimethyl sulfoxide casting solution of S31 to prepare an ATP-X / SPEEK mixed solution;

[0022] S33, the mixed solution obtained in S32 is poured on a glass plate, and after two drying processes, an ATP-X / SPEEK polymer composite membrane is obtained.

[0023] Further, if a strip-shaped perfluorosulfonic acid membrane is prepared in S2, the preparation steps in S3 are as follows:

[0024] The strip-shaped perfluorosulfonic acid membrane is added to a dimethylacetamide solution, and stirring is continuously performed until a perfluorosulfonic acid dimethylacetamide casting solution without solid phase residue is obtained.

[0025] ATP-X is added to the perfluorosulfonic acid dimethylacetamide casting solution, and after stirring until complete dispersion, ultrasonic treatment is performed to prepare an ATP-X / PFSA mixed solution.

[0026] The mixed solution obtained in S32 is poured on a glass plate, and after two drying processes, an ATP-X / SPEEK polymer composite membrane is obtained. The mixed solution obtained in S32 is poured on a glass plate, and after two drying processes, an ATP-X / SPEEK polymer composite membrane is obtained.

[0027] Further, the ATP-X material in S1 is ATP-H + , ATP-K + or ATP-Na + .

[0028] 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.

[0029] In S12, the centrifugal speed is 6000-8000 rad / min.

[0030] In S13, the ball milling speed is 200-400 rad / min, and the ball milling time is 10-20 min.

[0031] Further, in S21, the mass-volume ratio of polyether ether ketone powder to concentrated sulfuric acid is 1: (13-15) g / mL, and stirring is performed at a speed of 700-900 r / min at 50-60℃ for 65-80 min.

[0032] Further, in S31, the mass-volume ratio of SPEEK fiber to dimethyl sulfoxide solution is 1: (17-32) g / mL, and the stirring temperature is 50-60℃.

[0033] In the S32, the ATP-X is kept at 1-5 wt% of the SPEEK fiber, the stirring temperature is 50-60 DEG C, and the ultrasonic time is 5-10 min.

[0034] In the S33, the drying is first carried out at 70-80 DEG C for 12-24 h, and then at 100-120 DEG C for 5-12 h.

[0035] Further, in the S34, In the S34, the mass / volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution is 1:(26-28) g / mL, and the stirring temperature is 50-60 DEG C.

[0036] In the S34, In the S34, the ATP-X is kept at 1-3 wt% of the strip-shaped perfluorosulfonic acid membrane after drying, the stirring temperature is 50-60 DEG C, and the ultrasonic time is 5-10 min.

[0037] In the S34, In the S34, the drying is first carried out at 70-80 DEG C for 12-24 h, and then at 100-120 DEG C for 5-12 h.

[0038] Further, after the sulfonation reaction is completed, the sulfonation degree of the sulfonated polyether ether ketone is 55%-65%.

[0039] The beneficial effects of the present application are:

[0040] 1. The present application carries out ion exchange on the functionalization of attapulgite (ATP) material, due to the isomorphism substitution phenomenon, some trivalent cations such as Al (III) and Fe (III) partially replace Mg in the octahedral position, the structural defects on the surface and in the pore of the natural attapulgite make it have a surface negative charge, the cations exchanged in the pore prevent the penetration of active substances while improving the transmission rate of the supporting electrolyte cations, effectively improving the selectivity of the separator, improving the efficiency and cycle stability of the flow battery.

[0041] 2. When the present application is implemented in a neutral or alkaline system, the base treatment is carried out on the base material sulfonated polyether ether ketone (SPEEK) or perfluorosulfonic acid (PFSA), the prepared composite separator is a sodium ion type or potassium ion type composite separator, which can provide abundant ion carrying groups, improve the ion conduction performance, significantly reduce the active ion permeability, improve the performance of the flow battery, and the prepared composite separator can adapt to various systems of redox flow battery, has very wide flow battery applicability, and helps to promote the commercialization development of various flow batteries.

[0042] 3、The composite diaphragm preparation process of the present application, the raw materials used are abundant in reserves in China, low cost and green and environmentally friendly, the equipment used is easy to operate, and the preparation process is very simple, which helps to promote the development of commercial composite diaphragm materials for flow battery and promote the commercial production of flow battery. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0044] Figure 1 is the SEM diagram of the attapulgite clay without ionization treatment.

[0045] Figure 2 is the XRD diagram of the attapulgite clay before and after modification and the composite membrane prepared with different percentage of additive.

[0046] Figure 3 is the SEM diagram of the composite membrane prepared in Example 3.

[0047] Figure 4 is the charge-discharge curve diagram of Examples 1-6, wherein (a), (c) are respectively the charge-discharge curve diagrams of Example 1 in the all-vanadium and vanadium-titanium flow battery, (b), (d) are respectively the charge-discharge curve diagrams of Example 2 in the all-vanadium and vanadium-titanium flow battery, (e), (f) are respectively the charge-discharge curve diagrams of Example 3, Example 4 in the iron flow battery, (g), (h) are respectively the charge-discharge curve diagrams of Example 5, Example 6 in the zinc-iron flow battery.

[0048] Figure 5 is the capacity retention rate comparison diagram of Examples 1-2, Examples 5-6 of the present application, wherein (a), (c) are respectively the capacity retention rate comparison diagrams of Example 1 in the all-vanadium and vanadium-titanium flow battery, (b), (d) are respectively the capacity retention rate comparison diagrams of Example 2 in the all-vanadium and vanadium-titanium flow battery, (e), (f) are respectively the capacity retention rate comparison diagrams of Example 5, Example 6 in the zinc-iron flow battery.

[0049] Figure 6 is the coulomb efficiency comparison diagram of Examples 1-2, Examples 5-6 of the present application, wherein (a), (c) are respectively the coulomb efficiency comparison diagrams of Example 1 in the all-vanadium and vanadium-titanium flow battery, (b), (d) are respectively the coulomb efficiency comparison diagrams of Example 2 in the all-vanadium and vanadium-titanium flow battery, (e), (f) are respectively the coulomb efficiency comparison diagrams of Example 5, Example 6 in the zinc-iron flow battery.

[0050] Figure 7 is a comparison chart of energy efficiency of embodiments 1-2, 5-6 of the present application, wherein (a), (c) are respectively comparison charts of energy efficiency of embodiment 1 in all-vanadium, vanadium-titanium flow batteries, (b), (d) are respectively comparison charts of energy efficiency of embodiment 2 in all-vanadium, vanadium-titanium flow batteries, (e), (f) are respectively comparison charts of energy efficiency of embodiment 5, embodiment 6 in zinc-iron flow batteries.

[0051] Figure 8 is a comparison chart of long cycle each efficiency of embodiments 3, 4, comparative example 1, comparative example 2, embodiment 10, comparative example 10, comparative example 11, comparative example 13 of the present application, wherein (a) is a comparison chart of long cycle each efficiency of embodiment 3 in iron flow batteries, (b) is a comparison chart of long cycle each efficiency of embodiment 4 in iron flow batteries, (c) is a comparison chart of long cycle each efficiency of comparative example 1 in iron flow batteries, (d) is a comparison chart of long cycle each efficiency of comparative example 2 in iron flow batteries, (e) is a comparison chart of long cycle each efficiency of embodiment 10 in iron flow batteries, (f) is a comparison chart of long cycle each efficiency of comparative example 10 in iron flow batteries, (g) is a comparison chart of long cycle each efficiency of comparative example 11 in iron flow batteries, (h) is a comparison chart of long cycle each efficiency of comparative example 13 in iron flow batteries; in the chart, CE represents coulomb efficiency, EE represents energy retention, and DC represents discharge capacity.

[0052] Figure 9 is a comparison chart of rate of embodiment 3 tested by the present application.

[0053] Figure 10 is a comparison chart of peak power density of embodiment 3 tested by the present application.

[0054] Figure 11 is a SEM chart of embodiment 3.

[0055] Figure 12 is a SEM chart of comparative example 3.

[0056] Figure 13 is a chart of capacity retention and coulomb efficiency of comparative example 3, comparative example 4, embodiment 7, wherein (a) is a chart of capacity retention and coulomb efficiency of comparative example 3 in iron flow batteries, (b) is a chart of capacity retention and coulomb efficiency of comparative example 3 in iron flow batteries, (c) is a chart of capacity retention and coulomb efficiency of embodiment 7 in iron flow batteries.

[0057] Figure 14 is a SEM chart of comparative example 4.

[0058] Figure 15 is a SEM chart of embodiment 7.

[0059] Figure 16 is the capacity voltage graph of Comparative Example 1.

[0060] Figure 17 is the capacity retention graph of Comparative Example 2.

[0061] Figure 18 is the TEM graph of the modified attapulgite of Example 3 of the present application.

[0062] Figure 19 is the charge-discharge test curve graph of Example 8 of the present application.

[0063] Figure 20 is the capacity retention graph of Example 8 of the present application.

[0064] Figure 21 is the coulombic efficiency graph of Example 8 of the present application.

[0065] Figure 22 is the energy efficiency graph of Example 8 of the present application.

[0066] Figure 23 is the charge-discharge test curve graph of Example 9 of the present application.

[0067] Figure 24 is the capacity retention graph of Example 9 of the present application.

[0068] Figure 25 is the coulombic efficiency graph of Example 9 of the present application.

[0069] Figure 26 is the energy efficiency graph of Example 9 of the present application. DETAILED DESCRIPTION

[0070] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0071] The embodiment of the present application provides a preparation method of an ATP high-molecular composite diaphragm for a liquid flow battery, and the specific preparation steps are as follows:

[0072] Step S1, preparing ATP-X material (ATP-X material is ATP-H + , ATP-K + or ATP-Na + ), and the specific preparation steps are as follows:

[0073] S11, 1-10 g of attapulgite is weighed and added to a solution of one of 0.1-1.0 M sulfuric acid, potassium chloride or sodium chloride, a suspension is formed by magnetic stirring at room temperature for 12-24 h, and the cations in the solution and the metal ions of attapulgite are fully exchanged during stirring, so that the metal ions inside the crystal structure of attapulgite are exchanged into the cations in the solution, and the SEM image of attapulgite without ionization treatment is as shown in Figure 1

[0074] S12, the suspension obtained in S11 is centrifuged at a speed of 6000-8000 rad / min, and is alternately washed with ultrapure water and ethanol until the supernatant after washing is neutral, the supernatant is poured out, and the lower layer of the precipitate is the ionized ATP;

[0075] S13, the lower layer of ionized ATP is placed in a vacuum drying oven for drying, then ball-milled (dry milling) at a speed of 200-400 rad / min for 10-20 min, and sieved with a sieve to obtain ATP-X material.

[0076] Step 2, preparation of SPEEK fiber or perfluorosulfonic acid membrane, the specific steps are as follows:

[0077] S21, polyether ether ketone (PEEK) powder is subjected to a sulfonation reaction with 98 wt% concentrated sulfuric acid, the mass-volume ratio of PEEK to concentrated sulfuric acid is 1: (13-15) g / mL, stirring is carried out at a speed of 700-900 r / min at 50-60°C for 65-80 min, and a red-brown mixed solution of concentrated sulfuric acid and sulfonated polyether ether ketone is obtained;

[0078] S22, the red-brown mixed solution of S21 is slowly poured into a stirred ice-water mixture to obtain SPEEK fiber, which is repeatedly washed with deionized water until it is neutral, and is dried in an oven after being air-dried at room temperature (25°C) to obtain dried SPEEK fiber, the sulfonation degree of SPEEK is determined by existing technology to determine the proportion of sulfonic acid groups in the chain, that is, the degree of introduction of sulfonate groups, if it does not meet the expectation, the sulfonation time is adjusted according to the sulfonation degree, in the present application, the sulfonation degree of sulfonated polyether ether ketone needs to be kept at 55%-65%.

[0079] S21-S22 can be replaced by: the recycled Nafion 212 membrane (perfluorosulfonic acid proton exchange membrane) is subjected to acid washing with sulfuric acid, washed with ultrapure water and dried, then cut into strips to obtain strip-shaped perfluorosulfonic acid (PFSA) membrane, for a non-proton-conducting flow battery system, S23 is continued, and a proton-conducting flow system directly proceeds to step S3;

[0080] ​S23, for the non-proton conducting flow battery system, the prepared SPEEK fiber or strip-like perfluorosulfonic acid membrane is ionized by KOH solution or NaOH solution, then soaked and cleaned in deionized water to neutral, dried after air drying at room temperature, to obtain ionized SPEEK fiber or ionized strip-like perfluorosulfonic acid membrane.

[0081] Step S3, preparation of ATP-X-containing high molecular composite diaphragm, the specific steps are as follows:

[0082] S31, take 1.6~2.95 g of SPEEK fiber prepared in step S2, add to dimethyl sulfoxide solution, the mass volume ratio of SPEEK fiber and dimethyl sulfoxide solution is 1:(17~32) g / mL, then stir at 50~60 ℃, until the clear and transparent SPEEK dimethyl sulfoxide diaphragm pouring liquid is obtained;

[0083] Or take 1.78~1.9 g of prepared strip-like perfluorosulfonic acid membrane, add to dimethylacetamide solution, the mass volume ratio of strip-like perfluorosulfonic acid membrane and dimethylacetamide solution is 1:(26~28) g / mL, then stir at 50~60 ℃, until the PFSA dimethylacetamide diaphragm pouring liquid without solid phase residue is obtained;

[0084] S32, 0.0165~0.1475 g ATP-X is added to the SPEEK dimethyl sulfoxide diaphragm pouring liquid of S31, or 0.0178~0.057 g ATP-X is added to the PFSA dimethylacetamide diaphragm pouring liquid of S31 (ATP-X is 1~5wt% of the SPEEK fiber obtained in S2, or 1~3wt% of the strip-like perfluorosulfonic acid membrane obtained in S2); after stirring at 50~60 ℃ until completely dispersed, ultrasonic treatment for 5~15 min, to prepare ATP-X / SPEEK or ATP-X / PFSA mixed solution;

[0085] S33, pour the ATP-X composite high molecular mixed solution (ATP-X / SPEEK or ATP-X / PFSA) obtained in S32 on a glass plate, dry at 70~80 ℃ for 12~24 h, then dry at 100~120 ℃ for 5~12 h, to obtain ATP-X-containing high molecular composite diaphragm, the content of ATP-X in the composite diaphragm is 1~5wt%, and the thickness of the prepared high molecular composite diaphragm is 50~120 μm.

[0086] Example 1

[0087] Step 1, preparation of ATP-H + Materials, the specific steps are as follows:

[0088] S11, 10 g of attapulgite was added to 250 ml of 1.0 M sulfuric acid solution, and stirred at room temperature for 24 h to form a suspension;

[0089] S12, the suspension obtained in S11 was centrifuged at a speed of 8000 rad / min, and washed with ultrapure water and ethanol alternately until the supernatant was neutral, and the supernatant was poured out, and the lower layer of the precipitate was the protonated ATP.

[0090] S13, the lower layer of the protonated ATP was taken out and dried in a vacuum drying oven, and the dried hydrogen ionized ATP was ball milled at a speed of 400 rad / min for 20 min, and sieved to obtain ATP-H + material.

[0091] Step S2, preparation of SPEEK fiber, the specific steps are as follows:

[0092] S21, the PEEK powder was sulfonated with 98 wt% concentrated sulfuric acid, the mass volume ratio of PEEK powder to concentrated sulfuric acid was 1:13 g / mL, and stirred at 700 r / min at 60°C for 65 min to obtain a red-brown concentrated sulfuric acid and sulfonated polyether ether ketone mixed solution;

[0093] S22, the reacted solution was slowly poured into a stirred ice water mixture to obtain SPEEK fiber, and repeatedly washed with deionized water until neutral, and then dried in an oven after air drying at room temperature to obtain dried SPEEK fiber, and the sulfonation degree of SPEEK was measured to be 55% in this embodiment.

[0094] Step S3, preparation of high molecular composite membrane containing ATP-X, the specific steps are as follows:

[0095] S31, 1.6 g of dried SPEEK fiber in step S32 was added to a dimethyl sulfoxide solution, the mass volume ratio of SPEEK fiber to dimethyl sulfoxide solution was 1:32 g / mL, and then stirred at 60°C until a clear and transparent SPEEK dimethyl sulfoxide membrane casting solution was obtained;

[0096] S32, 0.048 g of ATP-H + material obtained in step S13 was added to the SPEEK dimethyl sulfoxide membrane casting solution in S31, and stirred at 60°C until completely dispersed, and then ultrasonic treated for 10 min to prepare an ATP-H + / SPEEK mixed solution;

[0097] S33, the ATP-H +The / SPEEK mixed solution was poured on a glass plate, dried at 75 ℃ for 12 h, and then dried at 100 ℃ for 10 h to obtain ATP-H + / SPEEK polymer composite diaphragm.

[0098] In this embodiment, ATP-H + / SPEEK polymer composite diaphragm has a thickness of 65 µm, ATP-H + has a content of 3 wt%, and the composite diaphragm is uniform and dense in texture, without ATP-H + particles, and has good mechanical properties.

[0099] The ATP-H + / SPEEK polymer composite diaphragm obtained in this embodiment was assembled into a full vanadium redox flow battery for testing, and compared with a full vanadium redox flow battery equipped with a Nafion 212 membrane, the charge-discharge test curves are shown in Figure 4 (a) of FIG. 6, and the comparison results of the capacity retention rate, coulombic efficiency and energy efficiency are shown in Figures 5-7 (a) of FIG. 6, respectively. The ATP-H + / SPEEK composite diaphragm prepared in this embodiment was used in a full vanadium redox flow battery, and the capacity retention rate was 62.1% after 100 cycles, the coulombic efficiency was 98.75%, and the energy efficiency was 84.01%.

[0100] The ATP-H + / SPEEK polymer composite diaphragm obtained in this embodiment was assembled into a vanadium-titanium redox flow battery for testing, and compared with a vanadium-titanium redox flow battery equipped with a Nafion 212 membrane, the charge-discharge test curves are shown in Figure 4 (c) of FIG. 7, and the comparison results of the capacity retention rate, coulombic efficiency and energy efficiency are shown in Figures 5-7 (c) of FIG. 7, respectively. The ATP-H + / SPEEK composite diaphragm prepared in this embodiment was used in a vanadium-titanium redox flow battery, and the capacity retention rate was 63.2% after 100 cycles, the coulombic efficiency was 99.8%, and the energy efficiency was 81.2%.

[0101] Example 2

[0102] The difference between this embodiment and Example 1 is that:

[0103] S2, instead of preparing SPEEK fibers, a perfluorosulfonic acid membrane is prepared:

[0104] S2 is replaced with: selecting perfluorosulfonic acid as the base film, fully pickling the recovered Nafion 212 diaphragm, drying after washing with ultrapure water, and cutting into strips to obtain a perfluorosulfonic acid membrane in the form of strips;

[0105] S31, 1.86 g of strip-shaped perfluorosulfonic acid membrane was taken and added to a dimethylacetamide solution, the mass-volume ratio of perfluorosulfonic acid and dimethylacetamide was 1:27 g / mL, then stirred at 60°C under heating conditions until a PFSA dimethylacetamide diaphragm casting liquid without solid phase residue was obtained;

[0106] S32, 0.0558 g of ATP-H + was added to the PFSA dimethylacetamide diaphragm casting liquid, and after stirring at 60°C under heating conditions until completely dispersed, ultrasonic was performed for 10 min to remove bubbles, to obtain an ATP-H + / PFSA mixed solution;

[0107] S33, the ATP-H + / PFSA mixed solution obtained in S32 was poured on a glass plate, and after drying at 80°C for 12 h and then drying at 120°C for 5 h, an ATP-H + / PFSA polymer composite diaphragm was obtained.

[0108] The rest were the same as in Example 1.

[0109] The ATP-H + / PFSA polymer composite diaphragm obtained in this example had a thickness of 52 µm, the content of ATP-H + was 3wt%, the composite diaphragm had uniform and dense texture, and there was no ATP-H + particle dissolution phenomenon, and at the same time had good mechanical properties, which was assembled into a vanadium redox flow battery and compared with a vanadium redox flow battery with Nafion 212 membrane, the charge-discharge test curve is shown in Figure 4 (b), and the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5-7 (b), respectively. The ATP-H + / PFSA polymer composite diaphragm prepared in this example was used in a vanadium redox flow battery, and after 100 cycles of charge-discharge of the battery, the capacity retention was 61.2%, the coulombic efficiency was 98.5%, and the energy efficiency was 82.3%.

[0110] The ATP-H + / PFSA polymer composite diaphragm obtained in this example was assembled into a vanadium-titanium redox flow battery and tested, and compared with a vanadium-titanium redox flow battery with Nafion 212 membrane, the charge-discharge test curve is shown in Figure 4 (d), and the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 5-7 (d), respectively. The ATP-H +The polymer composite diaphragm of / SPEEK is used for a vanadium-titanium flow battery, and after 100 cycles of charge and discharge of the battery, the capacity retention rate is 56.7%, the coulomb efficiency is 99.7%, and the energy efficiency is 80.1%.

[0111] Example 3

[0112] Step S1, preparation of ATP-K + Materials, the specific steps are as follows:

[0113] S11, 5 g of attapulgite is weighed and added to a 250 ml potassium chloride solution with a concentration of 0.5 M, and is magnetically stirred at room temperature for 20 h to form a suspension. After standing, the supernatant is taken and sodium hydroxide solution is added thereto, and whether a precipitate is formed is observed. If a precipitate is formed, a newly prepared 0.5 M potassium chloride solution is added again, and the above steps are repeated until no precipitate is formed when sodium hydroxide is added to the supernatant.

[0114] S12, the suspension obtained in S11 is centrifuged at a speed of 7000 rad / min, and is washed alternately with ultrapure water and ethanol until the supernatant is neutral. The supernatant is poured out, and the lower precipitate is the ATP ionized with potassium;

[0115] S13, the ATP ionized with potassium is placed in a vacuum drying oven for drying, and after drying, is ball milled at a speed of 400 rad / min for 20 min, and then is sieved to obtain ATP-K + Materials.

[0116] Step S2, preparation of SPEEK fiber, the specific steps are as follows:

[0117] S21, PEEK powder is subjected to a sulfonation reaction with 98 wt% concentrated sulfuric acid, and the mass-volume ratio of PEEK powder to concentrated sulfuric acid is 1:13 g / mL. The mixture is stirred at a speed of 700 r / min at 60°C for 75 min to obtain a red-brown mixed solution of concentrated sulfuric acid and sulfonated polyether ether ketone;

[0118] S22, the red-brown mixed solution is slowly poured into a stirred ice-water mixture to obtain SPEEK fiber, and is repeatedly washed with deionized water until neutral. After being air-dried at room temperature, the fiber is dried in an oven to obtain dried SPEEK fiber. The sulfonation degree of the SPEEK is determined to be 60% in this example;

[0119] S23, the obtained dried SPEEK is subjected to ionization treatment with KOH solution, and then is immersed and washed in deionized water until neutral. After being air-dried at room temperature, the fiber is dried to obtain potassium ionized SPEEK.

[0120] Step S3, preparation of a polymer composite diaphragm containing ATP-X, the specific steps are as follows:

[0121] S31, take 1.65g of potassium-ionized SPEEK from step S23 and add it to the dimethyl sulfoxide solution. The mass-volume ratio of SPEEK fiber to dimethyl sulfoxide solution is 1:32 g / mL. Then stir under heating at 55℃ until a clear and transparent SPEEK dimethyl sulfoxide membrane casting solution is obtained.

[0122] S32, take 0.0495 g ATP-K + Join SPEEK-K + In the dimethyl sulfoxide diaphragm casting solution, after stirring until completely dispersed at 55 °C, it was ultrasonically treated for 10 min to prepare ATP-K. + / SPEEK mixed solution;

[0123] S33, the ATP-K obtained from S32 + The SPEEK mixture was poured onto a glass plate and dried at 80 °C for 18 h, then dried at 120 °C for 5 h to obtain ATP-K. + SPEEK polymer composite membrane.

[0124] In this embodiment, the modified attapulgite material still maintains a good tubular structure, as shown in the SEM image. Figure 11 As shown, the TEM image is as follows Figure 18 As shown in the diagram, potassium ions are clearly visible in the energy spectrum, indicating that potassium ionization was successful and the prepared ATP-K + The SPEEK polymer composite membrane has a thickness of 65 µm and contains ATP-K. + The content is 3 wt%. For example... Figure 3 As shown, the composite ion exchange membrane has a uniform texture and contains ATP-K + The particles were uniformly distributed within the separator without dissolution. They were then assembled into an iron-sulfur flow battery for testing, and compared with an iron-sulfur flow battery equipped with a Nafion 212 membrane. The charge-discharge test curves are shown below. Figure 4 As shown in (e) of the figure, the efficiency comparison chart for the long cycle is as follows. Figure 8 As shown in (a) above, the peak power density comparison results are as follows: Figure 10 As shown, the ATP-K prepared in this embodiment... + SPEEK polymer composite separators are used in iron-sulfur flow batteries. After 2700 charge-discharge cycles, the battery retains 88.9% of its capacity, has a coulombic efficiency of 99.9%, and an energy efficiency of 82.7%.

[0125] In this embodiment, at 20 ~ 100 mA·cm -2 Comparison of ATP-K at current density +The energy efficiency of the battery assembled with the polymer composite separator of SPEEK and Nafion 212 membrane is shown in the rate comparison chart as shown in Figure 9 The polymer composite separator has higher energy efficiency at different current densities, indicating that the polymer composite separator has faster ion transmission capacity.

[0126] Example 4

[0127] The difference from Example 3 is that S2, instead of preparing SPEEK fiber, a perfluorosulfonic acid membrane is prepared:

[0128] Replace S21-S22 with: the used Nafion 212 separator is washed with sulfuric acid, then washed with ultrapure water, cut into strips after drying, and a perfluorosulfonic acid membrane in strip shape is obtained;

[0129] S23, the strip-shaped perfluorosulfonic acid membrane is ionized with KOH solution, then cleaned with deionized water until neutral, and dried after air drying at room temperature (25℃), to obtain a strip-shaped perfluorosulfonic acid membrane ionized with potassium ions;

[0130] S31, take 1.9 g of strip-shaped perfluorosulfonic acid membrane ionized with potassium ions, add to dimethylacetamide solution, the mass volume ratio of perfluorosulfonic acid and dimethylacetamide is 1:27 g / mL, then stir at 55℃ heating condition until PFSA dimethylacetamide separator pouring liquid without solid phase residue is obtained;

[0131] S32, take 0.038 g ATP-K + is added to the PFSA dimethylacetamide separator pouring liquid, after stirring at 55℃ heating condition until completely dispersed, ultrasonic treatment for 15 min, so that ATP-K + is fully dispersed in the organic pouring liquid to obtain ATP-K + / PFSA mixed solution;

[0132] S33, pour the ATP-K + / PFSA mixed solution obtained in S32 on a clean glass plate, dry at 75℃ for 18 h, then dry at 120℃ for 7 h to obtain ATP-K + / PFSA polymer composite separator.

[0133] The rest is the same as Example 3.

[0134] The ATP-K + / PFSA-K + polymer composite separator obtained in this example has a thickness of 54 µm, and the content of ATP-K + is 2wt%, the composite separator has uniform and dense texture, and no ATP-K +The particle dissolution phenomenon occurs, and the mechanical properties are good. The particles are loaded into an iron-sulfur flow battery for electrochemical testing, and the iron-sulfur flow battery loaded with a Nafion 212 diaphragm is compared. The charge-discharge test curve is as shown in (f) of Figure 4 , the long cycle efficiency comparison chart is as shown in (b) of Figure 8 , the ATP-K + / PFSA-K + of the embodiment has good mechanical properties. The polymer composite diaphragm is used in an iron-sulfur flow battery. After 2700 cycles of charge-discharge cycles of the battery, the capacity retention rate is 88.1%, the coulombic efficiency is 99.75%, and the energy efficiency is 78%.

[0135] Example 5

[0136] S1, preparation of ATP-Na + material, the specific steps are as follows:

[0137] S11, 10 g of attapulgite is weighed and added to a 250 ml sodium chloride solution with a concentration of 1.0 M. The suspension is formed under magnetic stirring at room temperature for 24 h. After standing, the supernatant is taken and sodium hydroxide solution is added to observe whether a precipitate is formed. If a precipitate is formed, a newly prepared 1.0 M sodium chloride solution is added again, and the above steps are repeated until no precipitate is formed when sodium hydroxide is added to the supernatant.

[0138] S12, the suspension obtained in S11 is centrifuged at a speed of 8000 rad / min, and is washed alternately with ultrapure water and ethanol until the supernatant is neutral. The supernatant is poured out, and the lower layer is the sodium ionized ATP;

[0139] S13, the lower layer of sodium ionized ATP is taken and dried in a vacuum drying oven. After drying, it is ball milled at a speed of 400 rad / min for 20 min, and then sieved to obtain ATP-Na + material.

[0140] Step S2, preparation of SPEEK fiber, the specific steps are as follows:

[0141] S21, PEEK powder is subjected to a sulfonation reaction with 98 wt% concentrated sulfuric acid. The mass-volume ratio of PEEK powder to concentrated sulfuric acid is 1:14 g / mL. The mixture is stirred at a speed of 800 r / min at 55°C for 78 min to obtain a red-brown concentrated sulfuric acid and a sulfonated polyether ether ketone solution;

[0142] S22, the red-brown mixed solution was slowly poured into the stirred ice water mixture to obtain the SPEEK fiber, and repeatedly washed with deionized water until neutral, and then dried at room temperature, and then dried in an oven to obtain the dried SPEEK fiber. The sulfonation degree of the SPEEK determined in this example was 61%;

[0143] S23, the obtained dried SPEEK was ionized by NaOH solution, and then soaked and washed with deionized water until neutral, and then dried at room temperature to obtain the sodium ionized SPEEK;

[0144] Step S3, preparation of ATP-X containing high molecular composite diaphragm, the specific steps are as follows:

[0145] S31, 1.65 g of sodium ionized SPEEK in step S23 was added to dimethyl sulfoxide, and the mass volume ratio of SPEEK fiber and dimethyl sulfoxide was 1:25 g / mL, then stirred at 60℃ until a clear and transparent SPEEK dimethyl sulfoxide diaphragm pouring liquid was obtained;

[0146] S32, 0.0495 g of ATP-Na + was added to the SPEEK dimethyl sulfoxide diaphragm pouring liquid in S31, and after stirring at 60℃ until completely dispersed, ultrasonic treatment was carried out for 15 min to prepare ATP-Na + / SPEEK mixed solution;

[0147] S33, the ATP-Na + / SPEEK mixed solution obtained in S32 was poured on a glass plate, and dried at 80℃ for 12 h, and then dried at 110℃ for 5 h to obtain ATP-Na + / SPEEK high molecular composite diaphragm.

[0148] The ATP-Na + / SPEEK high molecular composite diaphragm obtained in this example had a thickness of 65 µm, and the content of ATP-Na + was 3wt%, and the composite ion exchange membrane had uniform texture and no ATP-Na + particle dissolution phenomenon, and was loaded into a zinc-iron flow battery for electrochemical test, and compared with a zinc-iron flow battery loaded with Nafion 212 membrane. The charge-discharge test curve is shown in (g) of Figure 4 , and the comparison results of capacity retention rate, coulombic efficiency and energy efficiency are shown in (e) of Figures 5-7 , the ATP-Na + / SPEEK-Na +The polymer composite diaphragm is used for zinc-iron flow battery, and the capacity retention rate of the battery after 10000 cycles is 58.7%, the coulomb efficiency is 99.9%, and the energy efficiency is 84.3%.

[0149] Example 6

[0150] Different from example 5, the SPEEK fiber is not prepared, and a perfluorosulfonic acid membrane is prepared:

[0151] S21~S22 is replaced by: the used Nafion 212 diaphragm is fully pickled with sulfuric acid, then washed with ultrapure water, cut into strips after drying, and a strip-shaped perfluorosulfonic acid membrane is obtained;

[0152] S23, the strip-shaped perfluorosulfonic acid membrane is ionized by NaOH solution, then soaked and cleaned with deionized water until neutral, and dried after air drying at room temperature, to obtain a sodium ionized strip-shaped perfluorosulfonic acid membrane;

[0153] S31, take 1.90g of the sodium ionized strip-shaped perfluorosulfonic acid membrane, add it to a dimethylacetamide solution, and the mass volume ratio of PFSA-Na + and dimethylacetamide is 1:26 g / mL, then stir under the condition of 60 ℃ heating until the PFSA dimethylacetamide diaphragm pouring liquid without solid phase residue is obtained;

[0154] S32, take 0.057 g ATP-Na + is added to the PFSA dimethylacetamide diaphragm pouring liquid, and after stirring at 60 ℃ until completely dispersed, ultrasonic treatment is carried out for 10 min, to prepare an ATP-Na + / PFSA mixed solution;

[0155] S33, the ATP-Na + / PFSA mixed solution obtained in S32 is dried at 80 ℃ for 12 h, and then dried at 110 ℃ for 10 h, to obtain an ATP-Na + / PFSA polymer composite diaphragm.

[0156] The rest is the same as example 5.

[0157] In this example, the ATP-Na + / PFSA polymer composite diaphragm obtained has a thickness of 54 µm, and the content of ATP-Na + is 3wt%, the composite diaphragm is uniform and dense, and there is no ATP-Na + particle dissolution phenomenon, and has good mechanical properties, which is installed in a zinc-iron flow battery for testing, and compared with a zinc-iron flow battery installed with a Nafion 212 membrane, the charge-discharge test curve is as followsFigure 4 The comparative results of capacity retention, coulombic efficiency and energy efficiency are shown in (h) of FIG. 8, (i) of FIG. 8 and (j) of FIG. 8, respectively. Figures 5-7 As shown in (f) of FIG. 8, the ATP-Na + / PFSA-Na + The capacity retention of the polymer composite separator for zinc-iron redox flow battery after 10000 cycles is 72.4%, the coulombic efficiency is 99.9%, and the energy efficiency is 89.3%.

[0158] Example 7

[0159] The difference between this example and Example 3 is that:

[0160] In S13, the ball milling speed is 300 rad / min, and the ball milling time is 15 min.

[0161] In S32, 0.0165 g of ATP-K + is added when preparing the composite separator.

[0162] The rest is the same as Example 3.

[0163] The ATP-K + obtained in this example has a content of 1wt%, as shown in (a) of FIG. 10. + The thickness of the polymer composite separator is 63 µm, and the content of ATP-K + is 1wt%. Figure 15 As shown in (b) of FIG. 10, the content of ATP-K + decreases, and the ATP-K + dispersed on the surface of the separator is less. The separator is 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 of the polymer composite separator for iron-sulfur flow battery are shown in (c) of FIG. 10. Figure 13 The capacity retention of the battery after 1500 cycles is 92.4%, the coulombic efficiency is 99.8%, and the energy efficiency is 86.7%.

[0164] The capacity efficiency and coulombic efficiency of this example are still relatively stable, and appropriately reducing the addition amount of ATP-K + will not have too much impact on the selectivity of the separator.

[0165] Example 8

[0166] In S1, ATP-Na + material is prepared, and the specific steps are as follows:

[0167] S11, 1 g of attapulgite was weighed out and added to a 250 ml 0.1 M sodium chloride solution, and stirred magnetically at room temperature for 12 h to form a suspension, and after standing, the supernatant was taken and sodium hydroxide solution was added to observe whether a precipitate was formed, if a precipitate was formed, a newly prepared 0.1 M sodium chloride solution was added again, and the above steps were repeated until no precipitate was formed when sodium hydroxide was added to the supernatant;

[0168] S12, the suspension obtained in S11 was centrifuged at a speed of 6000 rad / min, and was washed alternately with ultrapure water and ethanol until the supernatant was neutral, the supernatant was poured out, and the lower layer was ATP ionized with sodium;

[0169] S13, the lower layer of ATP ionized with sodium was dried in a vacuum drying oven, and after drying, it was ball milled at a speed of 200 rad / min for 10 min, and then sieved to obtain ATP-Na + material;

[0170] Step S2, prepare SPEEK fiber, the specific steps are as follows:

[0171] S21, sulfonate PEEK powder with 98 wt% concentrated sulfuric acid, the mass-volume ratio of PEEK powder to concentrated sulfuric acid is 1:15 g / mL, stir at 900 r / min at 50°C for 80 min, get red-brown concentrated sulfuric acid and sulfonated polyether ether ketone mixed solution;

[0172] S22, slowly pour the red-brown mixed solution into the stirred ice water mixture to obtain SPEEK fiber, and repeatedly wash with deionized water until neutral, dry in the oven after drying at room temperature, get dry SPEEK fiber, the sulfonation degree of SPEEK is 65% in this embodiment;

[0173] S23, the obtained dry SPEEK is ionized with NaOH solution, then soaked and washed with deionized water until neutral, dry at room temperature, get sodium ionized SPEEK.

[0174] Step S3, prepare high molecular composite membrane containing ATP-X, the specific steps are as follows:

[0175] S31, take 2.95 g of sodium ionized SPEEK in step S23, add to dimethyl sulfoxide solution, the mass-volume ratio of SPEEK fiber to dimethyl sulfoxide is 1:17 g / mL, then stir under the condition of heating at 50°C until a clear and transparent SPEEK dimethyl sulfoxide membrane casting liquid is obtained;

[0176] S32, take 0.1475 g ATP-Na +The SPEEK dimethyl sulfoxide membrane casting solution added to S31 was stirred at 50℃ until completely dispersed, then ultrasonically treated for 5 min to prepare ATP-Na + / SPEEK mixed solution.

[0177] S33, ATP-Na + / SPEEK mixed solution obtained in S32 was poured onto a glass plate, dried at 70℃ for 24h, and then dried at 100℃ for 12h to obtain ATP-Na + / SPEEK polymer composite membrane.

[0178] The ATP-Na + / SPEEK polymer composite membrane obtained in this example had a thickness of 120 µm, and the content of ATP-Na + was 5%, and the composite ion exchange membrane had a uniform texture without ATP-Na + particles, and was used in a zinc-iron flow battery for electrochemical testing, and was compared with a zinc-iron flow battery with a Nafion 212 membrane. The charge-discharge test curves are shown in Figure 19 , and the comparison results of capacity retention, coulombic efficiency and energy efficiency are shown in Figures 20-22 , respectively. The ATP-Na + / SPEEK polymer composite membrane prepared in this example was used in a zinc-iron flow battery, and after 14000 cycles, the capacity retention was 68.7%, the coulombic efficiency was 99.8%, and the energy efficiency was 79.8%. By increasing the amount of sulfonated polyether ether ketone matrix to increase the thickness of the membrane, and by increasing the modified attapulgite to provide more ion transport channels, the ion selectivity was improved compared with the Nafion 212 membrane.

[0179] Example 9

[0180] The difference from Example 8 is that SPEEK fibers are not prepared, and a perfluorosulfonic acid membrane is prepared:

[0181] Replace S21-S22 with: The used Nafion 212 membrane is thoroughly pickled with sulfuric acid, then washed with ultrapure water, cut into strips after drying, and a perfluorosulfonic acid membrane in strip form is obtained;

[0182] S23, the strip-shaped perfluorosulfonic acid membrane is ionized with NaOH solution, then soaked and cleaned with deionized water until neutral, and dried at room temperature to obtain a sodium ionized strip-shaped perfluorosulfonic acid membrane;

[0183] S31, take 1.78g of sodium ionized strip-shaped perfluorosulfonic acid membrane, add to dimethylacetamide solution, and PFSA-Na +The mass-to-volume ratio of dimethylacetamide to PFSA was 1:28 g / mL, and the mixture was stirred under heating at 50°C until a PFSA dimethylacetamide membrane casting solution with no solid residue was obtained.

[0184] S32, take 0.0178 g ATP-Na + Add to PFSA dimethylacetamide diaphragm casting solution, stir at 50°C until completely dispersed, then sonicate for 5 min to prepare ATP-Na + / PFSA mixed solution;

[0185] S33, the ATP-Na obtained from S32 + The PFSA mixture was dried at 70 °C for 12 h, and then dried at 100 °C for 24 h to obtain ATP-Na. + / PFSA polymer composite membrane.

[0186] The rest are the same as in Example 8.

[0187] In this embodiment, the obtained ATP-Na + The PFSA polymer composite membrane has a thickness of 50 µm and contains ATP-Na. + The content is 1 wt%, the composite membrane has a uniform and dense texture, and is free of ATP-Na. + The particle dissolution phenomenon indicates good mechanical properties. It was tested in a zinc-iron flow battery and compared with a zinc-iron flow battery containing a Nafion 212 film. The charge-discharge test curves are shown below. Figures 23-24 As shown, the comparison results of capacity retention, coulombic efficiency, and energy efficiency are as follows: Figure 8 As shown, the ATP-Na prepared in this embodiment + The PFSA polymer composite separator used in zinc-iron flow batteries exhibits a capacity retention of 43.6% after 10,000 cycles, a coulombic efficiency of 99.7%, and an energy efficiency of 71.5%. It utilizes less perfluorosulfonic acid matrix, resulting in a thinner separator and thus requiring less modified attapulgite.

[0188] Example 10

[0189] The difference from Example 4 is that:

[0190] In S13, the ball milling speed is 300 rad / min and the ball milling time is 15 min.

[0191] Everything else is the same as in Example 4.

[0192] The ATP-K obtained in this embodiment + / PFSA-K +The high-molecular composite separator is used in the iron-sulfur flow battery, and a comparison chart of long cycle efficiency is as shown in (e) of Figure 16 After 2000 cycles of charge and discharge cycles of the battery, the capacity retention rate is 90.70%, the coulombic efficiency is 99.83%, and the energy efficiency is 74.34%.

[0193] Comparative Example 1

[0194] The difference from Example 3 is that:

[0195] The stirring time in S21 is 55 min;

[0196] The sulfonation degree of SPEEK in S22 is 50%.

[0197] The rest is the same as Example 3.

[0198] The ATP-K + / SPEEK high-molecular composite separator (sulfonation degree is 50%) obtained in the present comparative example is assembled into an iron-sulfur flow battery for testing, and a comparison chart of capacity and voltage of the composite separator with a sulfonation degree of 50% and 60% assembled into the battery is as shown in Figure 8 It can be seen from the chart that there is a large polarization in the internal resistance of the battery, and the separator prepared in the present comparative example is compared with an iron-sulfur flow battery with a Nafion 212 membrane, and the long cycle efficiency of the two is as shown in Figure 8 (c) of After 300 cycles of battery cycles, the capacity retention is 32.7%, the energy efficiency is low, only 34.6%, and the coulombic efficiency is 99.0%.

[0199] Comparative Example 2

[0200] The difference from Example 3 is that:

[0201] The stirring time in S21 is 85 min;

[0202] The sulfonation degree of SPEEK in S22 is 67%.

[0203] The rest is the same as Example 3.

[0204] The ATP-K + / SPEEK high-molecular composite separator (sulfonation degree is 67%) obtained in the present comparative example is assembled into an iron-sulfur flow battery for testing, and compared with an iron-sulfur flow battery with a Nafion 212 membrane, and a comparison chart of long cycle of the two is as shown in Figure 17As shown in (d), after 1000 cycles, the capacity retention is 54.8%, the energy efficiency is 43.8%, and the coulombic efficiency is 99.8%. This capacity retention is significantly lower than the 90.4% capacity retention of Nafion 212 after 1000 cycles. A comparison of capacity retention rates for SPEEK with 67% and 60% sulfonation is shown in the figure below. Figure 17 As shown, by Figure 12 It is evident that excessive sulfonation reduces capacity retention, affects normal battery operation, and degrades energy efficiency.

[0205] Comparative Example 3

[0206] 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.

[0207] Everything else is the same as in Example 3.

[0208] like Figure 13 As shown, in this embodiment, the morphology of ATP changes after the ball milling time is increased, and it loses its excellent one-dimensional tubular structure and agglomerates into irregular spheres.

[0209] The ATP-K obtained in this comparative example + The SPEEK polymer composite 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. The ATP-K membrane prepared in this comparative example... + SPEEK polymer composite separator is used in iron-sulfur flow batteries; coulombic efficiency and capacity retention are shown in the figure. Figure 13 As shown in (a), the battery retains 19.7% of its capacity after 1000 cycles, has a coulombic efficiency of 99.6%, and an energy efficiency of 76.5%.

[0210] The capacity decay of this comparative example is relatively fast, and the coulombic efficiency is unstable. This greatly affects the barrier effect of the separator on the active material and impairs the cycle life of the flow battery.

[0211] Comparative Example 4

[0212] The difference from Example 3 is that 0.099g of ATP-K was added during the preparation of the composite membrane in S32. + That is, ATP-K in the complex septum + The content is 6 wt%.

[0213] Everything else is the same as in Example 3.

[0214] The ATP-K obtained in this comparative example + / SPEEK-K +The polymer composite separator was assembled into an iron-sulfur flow battery for testing. The coulombic efficiency and capacity retention rate of the comparative example were as shown in (b) of Figure 2 After 520 cycles, the capacity of the battery decreased sharply, and the capacity retention rate was 17.5% and the coulombic efficiency was 69.3% and the energy efficiency was 47.5% at 531 cycles.

[0215] The XRD graphs of the attapulgite before and after modification and the composite membranes prepared with different addition percentages are as shown in Figure 14 It can be seen that, with the increase of the addition amount, the attapulgite is no longer dispersed in the micro-phase polymerization of the separator, and exhibits a characteristic peak belonging to attapulgite. Excessive addition of attapulgite is not conducive to the barrier of active substances. The separator with increased content of attapulgite is as shown in Figure 8 It can be seen that the aggregation caused by excessive addition seriously affects the battery performance.

[0216] Comparative Example 5

[0217] 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.

[0218] The rest are the same as Example 3.

[0219] The separator obtained in this comparative example has a size of attapulgite that is too large due to the short ball milling time, which cannot be well sieved, and cannot be well dispersed by directly adding it into the separator pouring liquid. There is local uneven dispersion, and after assembling the iron-sulfur flow battery, the active substances are quickly cross-contaminated, and the battery cannot run normally.

[0220] Comparative Example 6

[0221] The difference from Example 4 is that the ball milling time in S13 is 5 h.

[0222] The rest are the same as Example 4.

[0223] The separator obtained in this comparative example has the same problem as Comparative Example 3, the morphology changes to spherical shape, and the attapulgite cannot be well compounded with the separator. It is easy to fall off from the surface of the separator during the cycle process, and leaves uneven holes, which greatly reduces the barrier effect on the active substances, and the battery also cannot run normally.

[0224] Comparative Example 7

[0225] The difference from Example 3 is that 3 g of potassium ionized SPEEK fiber is taken in S31, and 0.015 g of ATP-K + is taken in S32.

[0226] The rest are the same as Example 3.

[0227] ATP-K prepared in the present comparative example + ATP-K / SPEEK-K + ATP-K in the polymer composite membrane + The content of ATP-K obtained in the present comparative example was 0.5wt%, and the thickness of the membrane was 110µm. The ATP-K obtained in the present comparative example was used in the polymer composite membrane. + ATP-K / SPEEK-K + The polymer composite membrane was used in the iron-sulfur flow battery. Due to the over-thick thickness of the membrane, the internal resistance of the assembled iron-sulfur flow battery was too large, the voltage drop was too large when the charge-discharge test was performed, the charge-discharge test could not be well performed in the charge-discharge interval of 0.4-1.4V of the iron-sulfur battery, and the energy efficiency of the battery was low and failed soon.

[0228] Comparative Example 8

[0229] The difference from Example 3 was that 0.5g of attapulgite was taken in S11, the mass-volume ratio of PEEK to concentrated sulfuric acid was 1:10g / mL in S21, the stirring temperature was 40℃, the mass-volume ratio of SPEEK fiber to dimethyl sulfoxide solution was 1:15g / mL in S31, and the stirring temperature was 30℃.

[0230] The rest was the same as Example 3.

[0231] In the present comparative example, the proportion of dimethyl sulfoxide solution was too low and the dissolution temperature was too low, the pouring liquid was too long to be dissolved to clear and transparent, and due to the adjustment of parameters in S21, the sulfonation degree was too low, the prepared membrane had the problems of uneven dissolution of the matrix and poor ion conduction capacity. The ATP-K obtained in the present comparative example was used in the polymer composite membrane. + ATP-K / SPEEK-K high polymer composite membrane was used in the iron-sulfur flow battery. During the charge-discharge cycle process, the energy efficiency was low due to the low concentration of sulfonic acid groups for ion exchange caused by the decrease of sulfonation degree, and due to the uneven dissolution, the thickness of the membrane was not uniform and the mechanical strength decreased, and obvious cross contamination appeared soon.

[0232] Comparative Example 9

[0233] The difference from Example 3 was that 15g of attapulgite was taken in S11, the mass-volume ratio of PEEK to concentrated sulfuric acid was 1:18g / mL in S21, the stirring temperature was 80℃, the mass-volume ratio of SPEEK fiber to dimethyl sulfoxide solution was 1:35g / mL in S31, and the stirring temperature was 75℃.

[0234] The rest was the same as Example 3.

[0235] In this comparative example, the proportion of concentrated sulfuric acid was increased, and the reaction time was extended. Under the same sulfonation reaction time, the resulting PEEK chains had too many sulfonic acid groups, resulting in excessive hydrophilicity. They were difficult to form into fibers in ice water, instead resembling a jelly-like gel. A small portion of the SPEEK that still formed fibers was dried and tested, revealing a sulfonation degree of 80%. ATP-K was then prepared under S31 conditions. + / SPEEK-K + When a polymer composite separator is used in an iron-sulfur flow battery, it partially dissolves after a few charge-discharge cycles, which significantly leads to a reaction between the positive and negative electrolytes. This causes the separator to lose its barrier function, ultimately resulting in battery failure.

[0236] Comparative Example 10

[0237] The difference from Example 4 is that: 2.5g of potassium-ionized strip-shaped perfluorosulfonic acid membrane was taken in S31, and 0.02g of ATP-K was taken in S32. + .

[0238] Everything else is the same as in Example 4.

[0239] The ATP-K obtained in this comparative example + / PFSA-K + ATP-K in polymeric composite membranes + The content of the polymer composite separator was 0.8 wt%, and the membrane thickness was 70 µm. The polymer composite separator obtained in this comparative example was used in an iron-sulfur flow battery. The comparison of long-cycle efficiencies is shown in the figure below. Figure 8 As shown in (f), after 1500 charge-discharge cycles, the battery retained 85.00% of its capacity, had a coulombic efficiency of 99.91%, and an energy efficiency of 71.84%. This is due to the increased membrane thickness and ATP-K... + The percentage content of the composite membrane decreased, and the test results of this comparative example were not as good as those of the Nafion 212 membrane. Furthermore, the increase in thickness was due to the increased amount of perfluorosulfonic acid matrix used, which would further increase the preparation cost of the composite membrane.

[0240] Comparative Example 11

[0241] The difference from Example 4 is that: 1.7g of potassium-ionized strip-shaped perfluorosulfonic acid membrane was used in S31, and 0.085g of ATP-K was used in S32. + .

[0242] Everything else is the same as in Example 4.

[0243] The ATP-K obtained in this comparative example + / PFSA-K + ATP-K in polymeric composite membranes +The content of ATP-K / PFSA-K is 5wt%, and the thickness of the composite diaphragm is 47 µm. The polymer composite diaphragm obtained by the present comparison example is used for an iron-sulfur flow battery, and the long cycle efficiency comparison chart is as shown in (g) of Figure 8 After 900 cycles of charge and discharge of the battery, the capacity retention rate is 26.80%, the coulombic efficiency is 99.8%, and the energy efficiency is 69.15%. The decrease in the amount of the diaphragm matrix leads to a decrease in the thickness of the diaphragm, and the addition amount of ATP-K + is increased. In the initial stage of the charge and discharge test, the ion transport path is shortened due to the decrease in the thickness of the diaphragm, and the energy efficiency is improved, but the stability of long-time operation is decreased, and rapid decay of the capacity and energy efficiency occurs after 800 cycles.

[0244] Comparative Example 12

[0245] The difference from Example 4 is that the mass-volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution in S31 is 1:20 g / mL, and stirring is carried out at 30°C.

[0246] The rest is the same as Example 4.

[0247] The polymer composite diaphragm obtained by the present comparison example is used for an iron-sulfur flow battery, and due to the low proportion of dimethylacetamide solution and the low dissolution temperature, the time for dissolving to a clear and transparent pouring liquid is too long. The ATP-K + / PFSA-K obtained by the present comparison example is used for an iron-sulfur flow battery, and due to the low proportion of dimethylacetamide solution and the low dissolution temperature, the time for dissolving to a clear and transparent pouring liquid is too long. + The polymer composite diaphragm is used for an iron-sulfur flow battery, and due to the non-uniform dissolution during the charge and discharge cycle process, the diaphragm thickness is not uniform, and the mechanical strength is decreased, and obvious cross contamination occurs soon, leading to the failure of the battery.

[0248] Comparative Example 13

[0249] The difference from Example 4 is that the mass-volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution in S31 is 1:30 g / mL, and stirring is carried out at 70°C.

[0250] The rest is the same as Example 4.

[0251] The polymer composite diaphragm obtained by the present comparison example is used for an iron-sulfur flow battery, and the long cycle efficiency comparison chart is as shown in (h) of ​ After 1500 cycles of charge and discharge of the battery, the capacity retention rate is 28.44%, the coulombic efficiency is 99.87%, and the energy efficiency is 62.13%. The increase in the proportion of dimethylacetamide solution leads to the easy residual of organic solvent on the diaphragm under the same drying time, and the steam pressure increases during stirring, which easily leads to the excessive air pressure in the bottle, so that the round-bottom flask plug is ejected, which increases the preparation requirements and the cost of the diaphragm preparation. The diaphragm prepared for the battery also reduces the service life of the battery due to the influence of the residual solvent.

[0252] The performance of the composite separators obtained in each embodiment and the comparative examples and assembled into batteries is shown in Table 1:

[0253] Table 1 Performance comparison of each embodiment and the comparative examples

[0254]

[0255] Due to the difference in the types of active substances on both sides in different systems, the structure and molecular size of the active substances themselves greatly affect the life and efficiency of the battery. The iron-based flow battery is superior to the vanadium-based flow battery in terms of life because the large molecular volume of ferricyanide has greater steric hindrance when passing through the separator, and the negative charge is not easy to pass through the separator under the influence of the Donnan effect.

[0256] As can be seen from Comparative Example 1 to Comparative Example 2, due to the decrease in the sulfonation degree, the proportion of grafted sulfonic acid groups decreases, and after potassium ionization, the ion exchange group density for exchanging potassium ions is low, so the ion exchange rate is limited, the battery resistance increases, there is a large polarization, and it is not conducive to the normal operation of the battery. For the high-sulfonation-degree separator, due to the increase in the sulfonation degree, the density of the hydrophilic group is too high, serious swelling occurs, the ion transport channel is enlarged, the ability to prevent cross-contamination of active substances is reduced, and the sulfur shuttle will form a barrier layer to ion exchange on the surface of the separator and the electrode, thereby reducing the energy efficiency.

[0257] The thickness of the composite separator of the present application is kept at 50-120 μm. The thickness of the separator will affect the barrier effect of the separator on the positive and negative active substances and the length of the ion transport channel, thereby affecting the ion transport performance of the separator. If the thickness of the separator is too thin, the active substances on both sides cannot be well blocked and can easily pass through the separator, leading to cross-contamination. If the thickness of the separator is too thick, it will hinder the transmission of ions that support the electrolyte, leading to an increase in the battery resistance and a decrease in the energy efficiency.

[0258] The attapulgite used in the present application is used to increase the ion transport channel and can accelerate ion transport. Increasing the content will increase the tubular transport channel, but excessive amount will cause the channels to pile up and intertwine, resulting in a large transport channel in the separator, so that the separator loses the screening effect on the active substances, leading to cross-contamination of the electrolyte.

[0259] As can be seen from Comparative Examples 3, 5 and 6, too short ball milling time is not conducive to the dispersion of attapulgite, and too long ball milling time will change the morphology of attapulgite, resulting in that the composite separator cannot achieve the expected use effect.

[0260] The application modifies the attapulgite which has one-dimensional tubular structure and reserves advantage in China, and combines the pre-ionized SPEEK matrix and PFSA matrix, and stably uses in the vanadium, vanadium titanium, iron sulfur, zinc iron and other various flow battery systems, and the suitable pore size and rich exchangeable cations make the modified attapulgite be well applied in the above systems. The addition amount, ball milling time and sulfonation degree are explored in the preparation process, the effective range of the application is determined, the simple preparation method further reduces the cost of large-scale application, and a solution is provided for the problem of large-scale application of flow battery in the separator.

[0261] Each of the embodiments in the specification is described in a related manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment mainly explains the difference from other embodiments. Especially, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts can be referred to the part of the method embodiment.

[0262] The above only describes the preferred embodiments of the application, and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for preparing an ATP polymer composite separator for a flow battery, characterized in that, The preparation steps are as follows: Step S1, Preparation of ATP-X material: S11, Add attapulgite clay to a solution of sulfuric acid, potassium chloride or sodium chloride, and stir at room temperature to form a suspension; S12, the suspension obtained from S11 is centrifuged and washed alternately with ultrapure water and ethanol until the supernatant is neutral after the last wash. The supernatant is poured off and the lower precipitate is the ionized ATP-X. S13, the lower layer of ionized ATP-X is dried, ball-milled and sieved to obtain ATP-X material; Step S2: Prepare SPEEK fiber or strip-shaped perfluorosulfonic acid membrane; Step S3: Prepare a polymeric composite membrane containing ATP-X; The ATP-X material mentioned in S1 is ATP-H. + ATP-K + or ATP-Na + , In step S11, 1-10 g of attapulgite clay is taken, the solution concentration is 0.1-1.0 M, and the stirring time is 12-24 h. In S12, the centrifugal speed is 6000~8000 rad / min; In step S13, the ball milling speed is 200~400 rad / min, and the ball milling time is 10~20 min; The SPEEK fiber preparation steps described in S2 are as follows: S21, sulfonate polyetheretherketone powder with concentrated sulfuric acid to obtain a reddish-brown mixed solution; S22, slowly pour the reddish-brown mixed solution into the stirred ice-water mixture to obtain SPEEK fiber, and wash it repeatedly with deionized water until neutral. After air drying at room temperature, dry SPEEK fiber is obtained. For non-proton-conducting flow battery systems, continue to S23; for proton-conducting flow battery systems, directly proceed to S3. S23. The prepared SPEEK fiber is ionized with either KOH solution or NaOH solution, then soaked and washed in deionized water until neutral, air-dried at room temperature, and then dried to obtain ionized SPEEK fiber.

2. The method for preparing an ATP polymer composite separator for a flow battery according to claim 1, characterized in that, The preparation steps of the strip-shaped perfluorosulfonic acid membrane described in S2 are as follows: The recovered perfluorosulfonic acid proton exchange membrane was thoroughly acid-washed with sulfuric acid, washed with ultrapure water, dried, and then cut into strips to obtain strip-shaped perfluorosulfonic acid membranes. For non-proton-conducting flow battery systems, further processing was carried out. The proton-conducting flow battery system directly undergoes S3; The strip-shaped perfluorosulfonic acid membrane was ionized with either KOH or NaOH solution, then soaked and washed in deionized water until neutral, and finally dried at room temperature to obtain the ionized strip-shaped perfluorosulfonic acid membrane.

3. The method for preparing an ATP polymer composite separator for a flow battery according to claim 1, characterized in that, After preparing SPEEK fibers in S2, the preparation steps of S3 are as follows: S31, SPEEK fiber is added to dimethyl sulfoxide solution and stirred continuously until a clear and transparent SPEEK dimethyl sulfoxide membrane casting solution is obtained; S32, ATP-X is added to the SPEEK dimethyl sulfoxide membrane casting solution in S31 to prepare an ATP-X / SPEEK mixed solution; S33: Pour the mixed solution obtained in S32 onto a glass plate and dry it twice to obtain the ATP-X / SPEEK polymer composite membrane.

4. The method for preparing an ATP polymer composite separator for a flow battery according to claim 2, characterized in that, After preparing the strip-shaped perfluorosulfonic acid membrane in S2, the preparation steps of S3 are as follows: Add the strip-shaped perfluorosulfonic acid membrane to the dimethylacetamide solution and stir continuously until a perfluorosulfonic acid dimethylacetamide membrane casting solution with no solid residue is obtained. ATP-X was added to the perfluorosulfonic acid dimethylacetamide membrane casting solution, stirred until completely dispersed, and then subjected to ultrasonic treatment to prepare an ATP-X / PFSA mixed solution. ,Will The resulting mixed solution was poured onto a glass plate and dried twice to obtain an ATP-X / PFSA polymeric composite membrane.

5. The method for preparing an ATP polymer composite separator for a flow battery according to claim 1, characterized in that, In S21, the mass-to-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 for 65~80 min at 50~60℃.

6. The method for preparing an ATP polymer composite separator for a flow battery according to claim 3, characterized in that, In S31, the mass-to-volume ratio of SPEEK fiber to dimethyl sulfoxide solution is 1:(17~32)g / mL, and the temperature during stirring is 50~60 ℃. In S32, ATP-X is maintained at 1-5 wt% of SPEEK fiber, the stirring temperature is 50-60℃, and the sonication time is 5-10 min; In step S33, the product is first dried at 70-80 ℃ for 12-24 hours, and then dried at 100-120 ℃ for 5-12 hours.

7. The method for preparing an ATP polymer composite separator for a flow battery according to claim 4, characterized in that, The In this process, the mass-to-volume ratio of the strip-shaped perfluorosulfonic acid membrane and the dimethylacetamide solution is 1:(26~28) g / mL, and the stirring temperature is 50~60 ℃; The In this process, ATP-X is maintained at 1-3 wt% of the dried strip-shaped perfluorosulfonic acid membrane, the stirring temperature is 50-60℃, and the sonication time is 5-10 min; The First, dry at 70~80 ℃ for 12~24 h, then dry at 100~120 ℃ for 5~12 h.

8. The method for preparing an ATP polymer composite separator for a flow battery according to claim 1, characterized in that, After the sulfonation reaction is completed, the degree of sulfonation of the sulfonated polyether ether ketone is 55%~65%.

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