Application of covalent organic polymers, negative electrode sheet and preparation method thereof, zinc-based flow battery, zinc ion battery

Abstract

The present invention relates to the technical fields of covalent organic polymers, flow batteries, and zinc ion batteries, and more particularly to the use of a covalent organic polymer in inhibiting dendrite growth at the negative electrode of a flow battery or an ion battery. The covalent organic polymer comprises one or more structural units represented by formula (1), formula (2), and formula (3); wherein M1, M2, and M3 are each independently selected from one or more metal elements of Group VIII, Group IIB, and Group IVA. The covalent organic polymer is used in the negative electrode of a zinc ion battery or an alkaline zinc-based flow battery, and can effectively inhibit the growth of zinc dendrites.

Description

Technical Field

[0001] The present invention relates to the technical field of covalent organic polymers, liquid flow batteries, and zinc ion batteries, and in particular to an application of a covalent organic polymer in inhibiting dendrite growth at the negative electrode of a liquid flow battery or an ion battery, a negative electrode sheet and a preparation method thereof, a zinc-based liquid flow battery, and a zinc ion battery. Background Art

[0002] The high capacity and cost-effectiveness of zinc metal batteries make them a promising alternative to lithium-ion batteries, especially for large-scale energy storage. However, due to the low redox potential of zinc metal (-0.76 V compared to the standard hydrogen electrode), it easily undergoes hydrogen evolution reaction (HER) with dissolved water molecules in the solvent when electrodeposited, leading to electrode corrosion failure and seriously shortening the battery life.

[0003] The above problems usually occur at the electrode / electrolyte interface and are closely related to the water molecules in the electrolyte. In order to reduce the activity of water around zinc, a common strategy is to reduce the water content around zinc ions. Most of the reported methods are to modify the solid electrolyte interface (SEI) on the surface of the Zn electrode, physically control the active H2O through size effects, or shield the active water molecules around Zn through bond interactions to regulate the Zn 2+ Furthermore, the zinc interface is sensitive to interfacial proton concentration (pH), and highly alkaline environments (pH ≥ 5.47) exacerbate the precipitation of inert byproducts. Therefore, it is crucial to utilize a carefully designed SEI interface to regulate the activity of water molecules surrounding zinc ions in solution and the microenvironment on the electrode surface.

[0004] The large-scale energy storage application of zinc-based flow batteries is subject to battery life issues, but relying solely on electrolyte flow to improve concentration polarization is far from enough. Zinc dendrites remain one of the most difficult problems affecting battery life. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problem in the prior art that zinc ion batteries and alkaline zinc-based liquid flow batteries have a negative electrode that is prone to dendrites or hydrogen evolution side reactions, resulting in a decrease in battery cycle performance. The present invention provides an application of a covalent organic polymer in inhibiting the growth of dendrites at the negative electrode of a liquid flow battery or an ion battery, a negative electrode sheet and a preparation method thereof, a zinc-based liquid flow battery, and a zinc ion battery. The covalent organic polymer can regulate the activity of water molecules around zinc ions in a solution. The covalent organic polymer is used in the negative electrode of a zinc ion battery or an alkaline zinc-based liquid flow battery and can effectively inhibit the growth of zinc dendrites.

[0006] In order to achieve the above-mentioned object, the present invention provides, on one hand, an application of a covalent organic polymer in inhibiting dendrite growth of a negative electrode of a flow battery or an ion battery, wherein the covalent organic polymer has one or more structural units shown in formula (1), formula (2) and formula (3);

[0007] (1) (2)

[0008] (3),

[0009] In formula (1), formula (2) and formula (3), M1, M2 and M3 are each independently selected from one or more metal elements of Group VIII, Group IIB and Group IVA.

[0010] A second aspect of the present invention provides a negative electrode sheet, comprising a substrate and a polymer layer disposed on the substrate;

[0011] The polymer layer includes the covalent organic polymer described in the present invention.

[0012] A third aspect of the present invention provides a method for preparing the negative electrode sheet of the present invention, the method comprising: applying a solution containing a covalent organic polymer to a surface of a substrate, and drying;

[0013] or

[0014] The substrate is contacted with a solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound, subjected to microwave reaction, separated, and the solid is dried;

[0015] The diamine nitrogen heterocyclic compound is selected from 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine or 2,5-diamino-1,3,4-thiadiazole;

[0016] M is M1, M2 or M3.

[0017] A fourth aspect of the present invention provides a zinc-based liquid flow battery, comprising: a negative electrode, a positive electrode and an electrolyte, wherein the negative electrode is the negative electrode sheet described in the present invention.

[0018] A fifth aspect of the present invention provides a zinc ion battery comprising: a negative electrode, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte; the negative electrode comprises a zinc foil and a polymer layer disposed on the zinc foil;

[0019] The polymer layer includes the covalent organic polymer described in the present invention.

[0020] Through the above technical solution, the covalent organic polymer described in the present invention can be used in zinc-ion batteries and alkaline zinc-based flow batteries to effectively inhibit the growth of zinc dendrites, thereby extending the life of the zinc negative electrode. It is speculated that this is because the unique skeleton structure formed by the covalent organic polymer described in the present invention can reduce the activity of water molecules around zinc ions on the electrode surface, reduce the occurrence of the side reaction HER, inhibit the growth of zinc dendrites, and thus extend the life of the zinc negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a SEM image of the covalent organic polymer synthesized in Example 1;

[0022] Figure 2 This is the SEM image of the electrode coated with the covalent organic polymer in Example 1;

[0023] Figure 3 The symmetrical battery assembled with the covalent organic polymer protected electrode in Example 1 was tested at 2 mAh cm -2 Cyclic stability test diagram under conditions;

[0024] Figure 4 SEM image of the electrode protected by the covalent organic polymer after cycling in Example 1;

[0025] Figure 5 This is the SEM image of the exposed zinc foil negative electrode surface in Comparative Example 1;

[0026] Figure 6 The symmetrical cell assembled with the bare zinc foil negative electrode of Comparative Example 1 was tested at 2 mA cm -2 Cyclic stability test diagram under conditions;

[0027] Figure 7 SEM image of the bare zinc foil negative electrode after cycling in Comparative Example 1;

[0028] Figure 8 The covalent organic polymer prepared in Example 1 13 C solid-state NMR spectroscopy. DETAILED DESCRIPTION

[0029] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0030] On the one hand, the present invention provides a use of a covalent organic polymer in inhibiting dendrite growth of a negative electrode of a flow battery or an ion battery, wherein the covalent organic polymer has one or more structural units represented by formula (1), formula (2) and formula (3);

[0031] (1) (2)

[0032] (3),

[0033] In formula (1), formula (2), and formula (3), n is each independently an integer of 1 to 10;

[0034] M1, M2, and M3 are each independently selected from one or more metal elements of Group VIII, Group IIB, and Group IVA.

[0035] According to a preferred embodiment of the present invention, M1, M2, and M3 are each independently selected from one or more of Zn, Ni, Co, Fe, and Sn, preferably Zn.

[0036] In the present invention, the structural unit of the covalent organic polymer is determined by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS), with reference to https: / / doi.org / 10.1016 / j.esci.2022.10.009; or the C skeleton structure is characterized by solid-state nuclear magnetic resonance spectroscopy. 3 C solid-state nuclear magnetic resonance spectra were measured at a frequency of 8 kHz on a Burker 400 M spectrometer. 3 C solid-state nuclear magnetic resonance spectroscopy illustrates the structure of the covalent organic polymer of the present invention.

[0037] In the present invention, there is no particular limitation on the preparation method of the covalent organic polymer. Exemplarily, the present invention provides a preparation method of the covalent organic polymer, comprising:

[0038] A solution of ions containing the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound is subjected to microwave reaction, separated, and the solid is dried;

[0039] The diamine nitrogen heterocyclic compound is selected from 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine or 2,5-diamino-1,3,4-thiadiazole;

[0040] M is M1, M2 or M3.

[0041] According to a preferred embodiment of the present invention, in the solution, the molar ratio of 1,2,4,5-tetracyanobenzene to the diamine nitrogen heterocyclic compound is 1:0.1-10.

[0042] According to a preferred embodiment of the present invention, in the solution, the molar ratio of 1,2,4,5-tetracyanobenzene to M is 1:0.1-10.

[0043] According to a preferred embodiment of the present invention, the concentration of 1,2,4,5-tetracyanobenzene in the solution is 0.1-10 mol / L.

[0044] According to a preferred embodiment of the present invention, the microwave reaction conditions include: temperature of 120-200°C, time of 5 min-4 h; microwave power of 300-600 W.

[0045] According to a preferred embodiment of the present invention, the drying conditions include: a temperature of 30-90° C. and a time of 6-24 hours.

[0046] According to a preferred embodiment of the present invention, in the solution, the solvent is selected from one or more of C1-C6 alcohols, N,N-dimethylformamide and N,N-dimethylacetamide, preferably one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

[0047] A second aspect of the present invention provides a negative electrode sheet, comprising a substrate and a polymer layer disposed on the substrate;

[0048] The polymer layer includes the covalent organic polymer described in the present invention.

[0049] In the present invention, there is no particular limitation on the type of the substrate. Any material used as a negative electrode for a flow battery or an aqueous zinc ion battery in the art can be used in the present invention. According to a preferred embodiment of the present invention, the substrate is selected from one or more of carbon cloth, graphite carbon felt, and metal foil; preferably, in the metal foil, the metal is selected from copper, titanium, zinc or stainless steel.

[0050] According to a preferred embodiment of the present invention, the thickness of the substrate is not higher than 50 mm, preferably 0.1-20 mm.

[0051] According to a preferred embodiment of the present invention, the thickness of the polymer layer is not higher than 200 μm, preferably 10-100 μm.

[0052] According to a preferred embodiment of the present invention, the content of the covalent organic polymer is 90-95 wt % of the mass of the polymer layer.

[0053] According to a preferred embodiment of the present invention, the polymer layer further comprises a binder; preferably, the mass ratio of the covalent organic polymer to the binder is 8-9:1; preferably, the binder is selected from polyvinyl pyrrolidone and / or polyvinylidene fluoride.

[0054] In the present invention, the covalent organic polymer can be loaded onto the surface of the substrate by coating or in-situ growth to form the negative electrode sheet. The third aspect of the present invention provides a method for preparing the negative electrode sheet of the present invention, the method comprising:

[0055] Coating loading: coating a solution containing a covalent organic polymer onto the substrate surface and drying; or

[0056] In-situ growth loading: the substrate is contacted with a solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound, subjected to microwave reaction, separated, and the solid is dried;

[0057] The diamine nitrogen heterocyclic compound is selected from 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine or 2,5-diamino-1,3,4-thiadiazole;

[0058] M is M1, M2 or M3.

[0059] According to a preferred embodiment of the present invention, the negative electrode sheet of the present invention is formed by in-situ growth loading, which can increase the life of the zinc negative electrode.

[0060] According to a preferred embodiment of the present invention, the solution containing the covalent organic polymer further contains a binder.

[0061] According to a preferred embodiment of the present invention, in the solution containing the covalent organic polymer, the solvent is selected from one or more of ethanol, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0062] In the present invention, as long as the solution containing the covalent organic polymer is coated on the surface of the substrate to form a polymer layer, there is no particular limitation on the coating method. According to a preferred embodiment of the present invention, the coating method is selected from blade coating, spin coating, etc.

[0063] According to a preferred embodiment of the present invention, in the solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and the diamine nitrogen heterocyclic compound, the molar ratio of 1,2,4,5-tetracyanobenzene to the diamine nitrogen heterocyclic compound is 1:0.1-10.

[0064] According to a preferred embodiment of the present invention, the molar ratio of 1,2,4,5-tetracyanobenzene to M is 1: 0.1-10.

[0065] According to a preferred embodiment of the present invention, in the solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and the diamine nitrogen heterocyclic compound, the concentration of 1,2,4,5-tetracyanobenzene is 0.1-10 mol / L.

[0066] According to a preferred embodiment of the present invention, the microwave reaction conditions include: temperature of 120-200° C., time of 5 min-4 h; microwave power of 300-600 W.

[0067] According to a preferred embodiment of the present invention, the drying conditions include: a temperature of 30-90° C. and a time of 6-24 hours.

[0068] According to a preferred embodiment of the present invention, in the solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound, the solvent is selected from one or more of C1-C6 alcohols, N,N-dimethylformamide and N,N-dimethylacetamide, preferably one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

[0069] A fourth aspect of the present invention provides a zinc-based liquid flow battery, comprising: a negative electrode, a positive electrode and an electrolyte, wherein the negative electrode is the negative electrode sheet described in the present invention.

[0070] The negative electrode sheet of the present invention is used in an alkaline zinc-based liquid flow battery, and can effectively inhibit the growth of zinc dendrites, thereby extending the life of the zinc negative electrode and improving the cycle life of the battery.

[0071] In the present invention, the zinc-based flow battery may or may not contain a separator, and is preferably a zinc-based flow battery without a separator.

[0072] In the present invention, the zinc-based flow battery can be a single-flow battery or a dual-flow battery.

[0073] In the present invention, there is no particular limitation on the type of the positive electrode. According to a preferred embodiment of the present invention, the positive electrode includes one or more of an air electrode, a nickel hydroxide electrode, manganese dioxide, and vanadium pentoxide.

[0074] According to a preferred embodiment of the present invention, the electrolyte comprises: a solvent, a monovalent cation hydroxide, and a zinc ion source.

[0075] According to a preferred embodiment of the present invention, the concentration of the monovalent cation hydroxide in the electrolyte is 1-10 mol / L.

[0076] According to a preferred embodiment of the present invention, the zinc ion source is calculated as zinc element, and the concentration of the zinc ion source is 0.1-0.8 mol / L.

[0077] According to a preferred embodiment of the present invention, the solvent is selected from water or a mixture of water and an organic matter, wherein the mixture of water and an organic matter contains at least 40% by volume of water, and the organic matter is selected from one or more of C1-C4 alcohols, ethylene glycol, acetic acid and glycerol.

[0078] According to a preferred embodiment of the present invention, the monovalent cation hydroxide is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonium hydroxide, preferably potassium hydroxide.

[0079] According to a preferred embodiment of the present invention, the zinc ion source is selected from one or more of zinc oxide, zinc hydroxide, zinc acetate, and zinc chloride, preferably zinc oxide.

[0080] A fifth aspect of the present invention provides a zinc ion battery comprising: a negative electrode, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte; the negative electrode comprises a zinc foil and a polymer layer disposed on the zinc foil;

[0081] The polymer layer includes the covalent organic polymer of the present invention. The covalent organic polymer is used in zinc ion batteries and can effectively inhibit the growth of zinc dendrites, thereby extending the life of the zinc negative electrode and improving the cycle life of the battery.

[0082] In the present invention, there is no particular limitation on the type of the electrolyte, and conventional electrolytes in the art can be used in the present invention. According to a preferred embodiment of the present invention, in the electrolyte, the electrolyte is selected from one or more of zinc sulfate (ZnSO4), zinc trifluoromethanesulfonate (Zn(CF3SO3)2), zinc chloride (ZnCl2), and zinc nitrate (ZnNO3); preferably, the concentration of the electrolyte is 0.1-3 M.

[0083] According to a preferred embodiment of the present invention, the thickness of the zinc foil is not higher than 50 mm, preferably 0.1-20 mm.

[0084] According to a preferred embodiment of the present invention, the thickness of the polymer layer is not higher than 200 μm, preferably 10-100 μm.

[0085] According to a preferred embodiment of the present invention, the content of the covalent organic polymer is 80-95 wt% of the mass of the polymer layer.

[0086] According to a preferred embodiment of the present invention, the polymer layer further comprises a binder.

[0087] According to a preferred embodiment of the present invention, the mass ratio of the covalent organic polymer to the binder is 8-9:1.

[0088] According to a preferred embodiment of the present invention, the binder is selected from polyvinyl pyrrolidone and / or polyvinylidene fluoride.

[0089] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0090] Example 1

[0091] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.2 mol of 3,5-diamino-1,2,4-triazole were dissolved in 10 ml of N,N-dimethylformamide as solution A; 0.1 mol of the metal salt zinc chloride was dissolved in 10 mL of ethylene glycol as solution B, where the concentration of zinc ions in solution B was 0.1 M; solution A and solution B were ultrasonically mixed for 15 min to obtain solution C;

[0092] (2) Place solution C in a microwave reactor, control the microwave power to 300W, the reaction temperature to 180℃, and the reaction time to 10 min. After the reaction is completed, wash the solution with deionized water until it is neutral, and then dry it at 60℃ for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in Figure 2. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M1 is Zn. 13 C solid-state NMR spectroscopy Figure 8 shown.

[0093] (3) Preparation of covalent organic polymer slurry: The covalent organic compound and the binder polyvinyl pyrrolidone were dissolved in N-methylpyrrolidone and recorded as solution D. The mass ratio of the covalent organic polymer to the binder was 9:1, the stirring temperature was 80 °C, and the stirring time was 6 h.

[0094] (4) Covalent organic polymer coating: The covalent organic polymer slurry solution D was evenly coated on the zinc foil using a doctor blade method. The thickness of the zinc foil was 0.1 mm, and the thickness of the covalent organic polymer was 50 μm. The coated zinc electrode was vacuum dried to remove the solvent at a drying temperature of 100°C for 6 h. After drying, a covalent organic polymer-protected zinc negative electrode was obtained.

[0095] The cross-sectional SEM image of the zinc anode protected by covalent organic polymer is shown in Figure 2. Figure 2 As shown, the organic covalent polymer material coated on the surface can be clearly seen.

[0096] Symmetrical cell assembly: The symmetrical cell was assembled in a standard CR2032 button cell. The cell was assembled by stacking the covalent organic polymer-protected zinc electrode, the separator (glass fiber separator, Whatman, GF / A), and the covalent organic polymer-protected zinc electrode in this order, and then dripping 2M ZnSO4 electrolyte. At 3 mA cm -2 Symmetrical battery cycle stability test was carried out under the conditions of .

[0097] Test results: Figure 3 As shown in the figure, it shows that the zinc anode protected by the covalent organic polymer can -2 The deposition and peeling were stable for more than 1300 hours under the conditions, and the electrode sheets after the cycle were further observed by SEM, such as Figure 4 As shown, no obvious zinc dendrite growth was found.

[0098] Example 2

[0099] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.2 mol of 3,5-diamino-1,2,4-triazole were dissolved in N,N-dimethylformamide as solution A, where the concentration of the organic ligand was 0.1 M. 0.1 mol of the metal salt tin chloride was dissolved in ethylene glycol as solution B, where the concentration of tin ions in solution B was 0.1 M. Solutions A and B were mixed evenly by ultrasonication for 15 min to obtain solution C.

[0100] (2) Solution C was placed in a microwave reactor, and the microwave power was controlled to 300 W, the reaction temperature was controlled to 180 °C, and the reaction time was controlled to 30 min. After the reaction, the solution was washed with deionized water and then dried at 60 °C for 6 h to obtain a covalent organic polymer. The covalent organic polymer has a structural unit shown in formula (1), wherein M1 is Sn.

[0101] (3) Preparation of covalent organic polymer slurry: The covalent organic compound and the binder polyvinyl pyrrolidone were dissolved in N-methylpyrrolidone and recorded as solution D. The mass ratio of the covalent organic polymer to the binder was 8:2, and the stirring temperature was 80 °C and the stirring time was 6 h.

[0102] (4) Covalent organic polymer coating: The covalent organic polymer slurry solution D was evenly coated on the zinc metal foil using a doctor blade method. The thickness of the metal foil was 0.5 mm, and the thickness of the covalent organic polymer was 10 μm. The coated zinc electrode was vacuum dried to remove the solvent at a drying temperature of 60 °C for 6 h. After drying, a metal negative electrode protected by the covalent organic polymer was obtained.

[0103] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, diaphragm (1cm 2 A zinc-nickel single-flow battery was assembled with a microporous separator (PP), a positive electrode sheet, a positive current collector, and end plate supports (the conductive surfaces of the negative and positive current collectors were 5.8 mm apart). The electrolyte flowed through the battery in a bottom-in, top-out pattern at a flow rate of 70 L / h. The electrolyte was 8M KOH and 0.6M ZnO.

[0104] Test conditions: The battery is charged and discharged at a constant current density of 1C, a charge time of 1 hour, and a discharge cut-off voltage of 0.8 V. Test end condition: The test is terminated when the battery capacity retention rate falls below 60%, which is considered to be unable to maintain stable capacity.

[0105] Test results:

[0106] The assembled zinc-nickel flow battery can stably charge and discharge for 100 cycles.

[0107] Example 3

[0108] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.1 mol of 2,5-diamino-1,3,4-thiadiazole were dissolved in N,N-dimethylformamide as solution A, where the concentration of the organic ligand was 0.1 M. 0.01 mol of ferric chloride was dissolved in ethylene glycol as solution B, where the concentration of Fe ions in solution B was 0.1 M. Solutions A and B were mixed evenly by ultrasonication for 15 min to obtain solution C.

[0109] (2) Solution C was placed in a microwave reactor, and the microwave power was controlled to 600 W, the reaction temperature was controlled to 120 °C, and the reaction time was controlled to 1 h. After the reaction, the solution was washed with deionized water and then dried at 60 °C for 6 h to obtain a covalent organic polymer. The covalent organic polymer has a structural unit shown in formula (2), wherein M2 is Fe.

[0110] (3) Preparation of covalent organic polymer slurry: The covalent organic compound and the binder polyvinyl pyrrolidone were dissolved in N-methylpyrrolidone and recorded as solution D. The mass ratio of the covalent organic polymer to the binder was 9:1, the stirring temperature was 80 °C, and the stirring time was 6 h.

[0111] (4) Covalent organic polymer coating: The covalent organic polymer slurry solution D was evenly coated on the zinc foil using a doctor blade method. The thickness of the zinc foil was 0.1 mm, and the thickness of the covalent organic polymer was 100 μm. The coated zinc electrode was vacuum dried to remove the solvent at a drying temperature of 100°C for 6 h. After drying, a covalent organic polymer-protected zinc negative electrode was obtained.

[0112] Symmetrical cell assembly: The symmetrical cell was assembled in a standard CR2032 button cell. The cell was assembled by stacking the covalent organic polymer-protected zinc electrode, the separator (glass fiber separator, Whatman, GF / A), and the covalent organic polymer-protected zinc electrode in this order, and then dripping 2M ZnSO4 electrolyte. At 3 mA cm -2 Symmetrical battery cycle stability test was carried out under the conditions of .

[0113] Test results: at 3 mA cm -2 Stable deposition and stripping conditions for 1100 hours.

[0114] Example 4

[0115] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.01 mol of 2,6-diaminopyridine were dissolved in N,N-dimethylformamide as solution A, where the concentration of the organic ligand was 1 M. 0.02 mol of cobalt chloride was dissolved in ethylene glycol as solution B, where the concentration of Co ions in solution B was 0.1 M. Solutions A and B were ultrasonically mixed for 15 min to obtain solution C.

[0116] (2) The carbon felt was immersed in solution C and placed in a microwave reactor. The microwave power was controlled to 300 W, the reaction temperature was controlled to 200 °C, and the reaction time was controlled to 40 min. After the reaction, the solution was washed with deionized water and then dried at 60 °C for 6 h. The carbon felt modified with a covalent organic polymer was obtained by in situ growth. The covalent organic polymer has a structural unit shown in formula (3), wherein M3 is Co.

[0117] (3) The carbon felt electrode on which the covalent organic polymer was grown was vacuum dried to remove the solvent at a drying temperature of 60 °C for 6 h. After drying, a carbon felt negative electrode protected by the covalent organic polymer was obtained.

[0118] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode carbon felt, separator (1cm 2A zinc-nickel single-flow battery was assembled using a microporous separator (PP), a positive electrode sheet, a positive current collector, and end plate supports (the conductive surfaces of the negative and positive current collectors were 5.8 mm apart). The electrolyte flowed through the battery in a bottom-in, top-out pattern at a flow rate of 70 L / h. The electrolyte was 8 M KOH and 0.6 M ZnO.

[0119] Test conditions: The battery is charged and discharged at a constant current density of 1C, a charge time of 1 hour, and a discharge cut-off voltage of 0.8 V. Test end condition: The test is terminated when the battery capacity retention rate falls below 60%, which is considered to be unable to maintain stable capacity.

[0120] Test results:

[0121] The assembled zinc-nickel flow battery can stably charge and discharge for 90 cycles.

[0122] Example 5

[0123] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.2 mol of 3,5-diamino-1,2,4-triazole were dissolved in 10 ml of N,N-dimethylformamide as solution A; 0.1 mol of ferric chloride was dissolved in 10 mL of ethylene glycol as solution B, where the concentration of Fe ions in solution B was 0.1 M; solution A and solution B were mixed uniformly by ultrasonication for 15 min to obtain solution C;

[0124] (2) Place solution C in a microwave reactor, control the microwave power to 300W, the reaction temperature to 180℃, and the reaction time to 10 min. After the reaction is completed, wash the solution with deionized water until it is neutral, and then dry it at 60℃ for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in Figure 2. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M1 is Fe.

[0125] (3) Preparation of covalent organic polymer slurry: The covalent organic compound and the binder polyvinyl pyrrolidone were dissolved in N-methylpyrrolidone and recorded as solution D. The mass ratio of the covalent organic polymer to the binder was 9:1, the stirring temperature was 80 °C, and the stirring time was 6 h.

[0126] (4) Covalent organic polymer coating: The covalent organic polymer slurry solution D was evenly coated on the zinc foil using a doctor blade method. The thickness of the zinc foil was 0.1 mm, and the thickness of the covalent organic polymer was 100 μm. The coated zinc electrode was vacuum dried to remove the solvent at a drying temperature of 100°C for 6 h. After drying, a covalent organic polymer-protected zinc negative electrode was obtained.

[0127] Symmetrical cell assembly: The symmetrical cell was assembled in a standard CR2032 button cell. The cell was assembled by stacking the covalent organic polymer-protected zinc electrode, the separator (glass fiber separator, Whatman, GF / A), and the covalent organic polymer-protected zinc electrode in this order, and then dripping 2M ZnSO4 electrolyte. At 3 mA cm -2 Symmetrical battery cycle stability test was carried out under the conditions of .

[0128] Test results: at 3 mA cm -2 Stable deposition and stripping conditions for 1000 hours.

[0129] Example 6

[0130] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.2 mol of 3,5-diamino-1,2,4-triazole were dissolved in 10 ml of N,N-dimethylformamide and recorded as solution A; 0.1 mol of the metal salt zinc chloride was dissolved in 10 mL of ethylene glycol and recorded as solution B, where the concentration of zinc ions in solution B was 0.1 M; solution A and solution B were ultrasonically mixed for 15 min to obtain solution C;

[0131] (2) Place solution C in a microwave reactor, control the microwave power to 300W, the reaction temperature to 180℃, and the reaction time to 10 min. After the reaction is completed, wash the solution with deionized water until it is neutral, and then dry it at 60℃ for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in Figure 2. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M1 is Zn.

[0132] (3) Preparation of covalent organic polymer slurry: The covalent organic compound and the binder polyvinyl pyrrolidone were dissolved in N-methylpyrrolidone and recorded as solution D. The mass ratio of the covalent organic polymer to the binder was 8:2, and the stirring temperature was 80 °C and the stirring time was 6 h.

[0133] (4) Covalent organic polymer coating: The covalent organic polymer slurry solution D was evenly coated on the zinc metal foil using a doctor blade method. The thickness of the metal foil was 0.5 mm, and the thickness of the covalent organic polymer was 10 μm. The coated zinc electrode was vacuum dried to remove the solvent at a drying temperature of 60 °C for 6 h. After drying, a metal negative electrode protected by the covalent organic polymer was obtained.

[0134] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, diaphragm (1cm2 A zinc-nickel single-flow battery was assembled with a microporous separator (PP), a positive electrode sheet, a positive current collector, and end plate supports (the conductive surfaces of the negative and positive current collectors were 5.8 mm apart). The electrolyte flowed through the battery in a bottom-in, top-out pattern at a flow rate of 70 L / h. The electrolyte was 8M KOH and 0.6M ZnO.

[0135] Test conditions: The battery is charged and discharged at a constant current density of 1C, a charge time of 1 hour, and a discharge cut-off voltage of 0.8 V. Test end condition: The test is terminated when the battery capacity retention rate falls below 60%, which is considered to be unable to maintain stable capacity.

[0136] Test results:

[0137] The assembled zinc-nickel flow battery can stably charge and discharge for 120 cycles.

[0138] Example 7

[0139] (1) Synthesis of covalent organic polymers: 0.1 mol of the organic ligand 1,2,4,5-tetracyanobenzene and 0.2 mol of 3,5-diamino-1,2,4-triazole were dissolved in 10 ml of N,N-dimethylformamide and recorded as solution A; 0.1 mol of the metal salt zinc chloride was dissolved in 10 mL of ethylene glycol and recorded as solution B, where the concentration of zinc ions in solution B was 0.1 M; solution A and solution B were ultrasonically mixed for 15 min to obtain solution C;

[0140] (2) A zinc metal foil (0.5 mm thick) was immersed in solution C and placed in a microwave reactor. The microwave power was controlled at 300 W, the reaction temperature was 180°C, and the reaction time was 10 min. After the reaction, the solution was washed with deionized water until neutral and then dried at 60°C for 6 h. A covalent organic polymer-modified zinc metal foil was obtained by in situ growth. The covalent organic polymer had a structural unit shown in formula (1), where M1 was Zn.

[0141] (3) The zinc metal foil electrode on which the covalent organic polymer was grown was vacuum dried to remove the solvent at a drying temperature of 60 °C for 6 h. After drying, a zinc metal foil negative electrode protected by the covalent organic polymer was obtained.

[0142] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, diaphragm (1cm 2A zinc-nickel single-flow battery was assembled with a microporous separator (PP), a positive electrode sheet, a positive current collector, and end plate supports (the conductive surfaces of the negative and positive current collectors were 5.8 mm apart). The electrolyte flowed through the battery in a bottom-in, top-out pattern at a flow rate of 70 L / h. The electrolyte was 8M KOH and 0.6M ZnO.

[0143] Test conditions: The battery is charged and discharged at a constant current density of 1C, a charge time of 1 hour, and a discharge cut-off voltage of 0.8 V. Test end condition: The test is terminated when the battery capacity retention rate falls below 60%, which is considered to be unable to maintain stable capacity.

[0144] Test results:

[0145] The assembled zinc-nickel flow battery can stably charge and discharge for 128 cycles.

[0146] Comparative Example 1

[0147] A symmetrical battery was assembled according to the method of Example 1, except that zinc foil (the thickness of the zinc foil was 0.5 mm) was used as the negative electrode instead of the zinc electrode protected by the covalent organic polymer. Other conditions were the same as those of Example 1.

[0148] Symmetrical battery cycling stability test, at 2 mAh cm -2 Stable deposition and stripping under conditions.

[0149] Test results:

[0150] like Figure 6 As shown in the figure, the Zn anode without covalent organic polymer protection has a high -2 Under these conditions, the deposition and peeling can only be stably carried out for less than 100 hours. Figure 7 As shown in Figure 3, obvious wrinkles and irregular dendrites were found on the surface of the zinc electrode.

[0151] Comparative Example 2

[0152] The flow battery was assembled according to the method of Example 2, except that zinc foil (the thickness of the zinc foil was 0.5 mm) was used instead of the zinc electrode protected by the covalent organic polymer as the negative electrode. The other conditions were the same as those of Example 2.

[0153] Test conditions: 1C was used as the constant current density for charge and discharge, the battery was charged and discharged at a rate of 1C, the charging time was 1 hour, and the discharge cut-off voltage was 0.8 V.

[0154] Test results:

[0155] The assembled zinc-nickel flow battery can only stably charge and discharge for 20 cycles.

Claims

1. A covalent organic polymer for inhibiting the growth of negative electrode dendrites in a flow battery or an ion battery, characterized in that: The covalent organic polymer has one or more structural units represented by formula (1), formula (2) and formula (3); （1）、 （2）、 （3）， In formula (1), formula (2) and formula (3), M1, M2 and M3 are each independently selected from one or more metal elements of Group VIII, Group IIB and Group IVA.

2. The use according to claim 1, wherein M1, M2, and M3 are each independently selected from one or more of Zn, Ni, Co, Fe, and Sn.

3. The use according to claim 1 or 2, wherein: M1, M2, and M3 are Zn.

4. The use according to claim 1 or 2, wherein: The method for preparing the covalent organic polymer comprises: A solution of ions containing the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound is subjected to microwave reaction, separated, and the solid is dried; The diamine nitrogen heterocyclic compound is selected from 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine or 2,5-diamino-1,3,4-thiadiazole; M is M1, M2 or M3.

5. The use according to claim 4, wherein: In the solution, the molar ratio of 1,2,4,5-tetracyanobenzene to the diamine nitrogen heterocyclic compound is 1:0.1-10; and / or The molar ratio of 1,2,4,5-tetracyanobenzene to M is 1: 0.1-10; and / or In the solution, the concentration of 1,2,4,5-tetracyanobenzene is 0.1-10 mol / L.

6. The use according to claim 4, wherein: Microwave reaction conditions include: temperature 120-200 ° C, time 5 min-4 h; microwave power 300-600 W; and / or Drying conditions include: temperature of 30-90°C, time of 6-24h; and / or In the solution, the solvent is selected from one or more of C1-C6 alcohols, N,N-dimethylformamide and N,N-dimethylacetamide.

7. The use according to claim 6, wherein: In the solution, the solvent is one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

8. A negative electrode sheet, characterized in that: The negative electrode sheet includes a substrate and a polymer layer disposed on the substrate; The polymer layer comprises the covalent organic polymer according to any one of claims 1-7.

9. The negative electrode sheet according to claim 8, wherein: The substrate is selected from one or more of carbon cloth, graphite carbon felt, and metal foil.

10. The negative electrode sheet according to claim 9, wherein: In the metal foil, the metal is selected from copper, titanium, zinc or stainless steel.

11. The negative electrode sheet according to claim 9, wherein: The thickness of the substrate is not more than 50 mm; and / or The thickness of the polymer layer is not higher than 200 μm.

12. The negative electrode sheet according to claim 11, wherein: The thickness of the substrate is 0.1-20 mm; the thickness of the polymer layer is 10-100 μm.

13. The negative electrode sheet according to claim 8 or 9, wherein: The content of the covalent organic polymer is 90-95 wt % of the mass of the polymer layer. 14 . The negative electrode sheet according to claim 13 , wherein the polymer layer further comprises a binder; the mass ratio of the covalent organic polymer to the binder is 8-9:1; and the binder is selected from polyvinyl pyrrolidone and / or polyvinylidene fluoride.

15. The method for preparing a negative electrode sheet according to any one of claims 8 to 14, characterized in that: The method includes: A solution containing a covalent organic polymer is applied to the substrate surface and dried.

16. The preparation method according to claim 15, wherein The solution containing the covalent organic polymer also contains a binder; in the solution containing the covalent organic polymer, the solvent is selected from one or more of ethanol, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

17. The preparation method according to claim 15, wherein The coating method is selected from blade coating or spin coating; or The substrate is contacted with a solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound, subjected to microwave reaction, separated, and the solid is dried; The diamine nitrogen heterocyclic compound is selected from 3,5-diamino-1,2,4-triazole, 2,6-diaminopyridine or 2,5-diamino-1,3,4-thiadiazole; M is M1, M2 or M3.

18. The preparation method according to claim 17, wherein In a solution containing ions of a metal element M, 1,2,4,5-tetracyanobenzene and a diamine nitrogen heterocyclic compound, the molar ratio of 1,2,4,5-tetracyanobenzene to the diamine nitrogen heterocyclic compound is 1:0.1-10; The molar ratio of 1,2,4,5-tetracyanobenzene to M is 1: 0.1-10; In the solution, the concentration of 1,2,4,5-tetracyanobenzene is 0.1-10 mol / L; The microwave reaction conditions include: temperature 120-200°C, time 5 min-4 h; microwave power 300-600 W; Drying conditions include: temperature of 30-90°C, time of 6-24h; In the solution, the solvent is selected from one or more of C1-C6 alcohols, N,N-dimethylformamide and N,N-dimethylacetamide.

19. A zinc-based flow battery comprising: A negative electrode, a positive electrode and an electrolyte, characterized in that the negative electrode is the negative electrode sheet according to any one of claims 8 to 14.

20. A zinc ion battery comprising: A negative electrode, a positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the negative electrode comprises a zinc foil and a polymer layer disposed on the zinc foil; The polymer layer comprises the covalent organic polymer according to any one of claims 1-7.

21. The zinc ion battery according to claim 20, wherein In the electrolyte, the electrolyte is selected from one or more of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, and zinc nitrate; the concentration of the electrolyte is 0.1-3 M; The thickness of the zinc foil shall not exceed 50 mm; The thickness of the polymer layer is not higher than 200 μm.

22. The zinc ion battery according to claim 21, wherein The thickness of the zinc foil is 0.1-20 mm; the thickness of the polymer layer is 10-100 μm.

23. The zinc ion battery according to claim 20, wherein The content of the covalent organic polymer is 80-95 wt % of the mass of the polymer layer.

24. The zinc ion battery according to claim 20, wherein The polymer layer further comprises a binder; the mass ratio of the covalent organic polymer to the binder is 8-9:1; the binder is selected from polyvinyl pyrrolidone and / or polyvinylidene fluoride.

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