Application of covalent organic polymer, negative plate, preparation method of negative plate, zinc-based flow battery and zinc ion battery

Abstract

The invention relates to the technical field of covalent organic polymers, flow batteries and zinc ion batteries, in particular to application of a covalent organic polymer in inhibition of dendritic crystal growth of a negative electrode of a flow battery or an ion battery, and the covalent organic polymer has one or more of structural units as shown in a formula (1), a formula (2) and a formula (3). In the formula (1), the formula (2) and the formula (3), M1, M2 and M3 are independently selected from one or more of VIII group metal elements, IIB group metal elements and IVA group metal elements. The covalent organic polymer is used for negative electrodes of zinc ion batteries and alkaline zinc-based flow batteries, and can effectively inhibit 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 the growth of negative electrode dendrites 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 in 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 electrodeposition occurs, leading to electrode corrosion failure, which seriously affects 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 current reports are to modify the solid electrolyte interface (SEI) on the surface of the Zn electrode to reduce the size effect of active H 2 O can be physically controlled or shielded by bond interactions with active water molecules around Zn to regulate the Zn 2+ In addition, the zinc interface is also very sensitive to the interfacial proton concentration (pH value), and a high alkaline environment (pH value ≥ 5.47) will aggravate the precipitation of inert byproducts. Therefore, it is very important to use a carefully designed SEI interface to regulate the activity of water molecules around zinc ions in the solution and the microenvironment of the electrode surface.

[0004] The large-scale energy storage application of zinc-based flow batteries is constrained by battery life issues, but improving concentration polarization by electrolyte flow alone 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 that zinc ion batteries and alkaline zinc-based liquid flow batteries in the prior art have negative electrodes that are prone to produce 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 for 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 the growth of negative electrode dendrites of a flow battery or an ion battery, wherein the covalent organic polymer has one or more of the structural units shown in formula (1), formula (2) and formula (3);

[0007]

[0008] In formula (1), formula (2) and formula (3), M 1 、M 2 、M 3 Each is independently selected from one or more of Group VIII, IIB and IVA metal elements.

[0009] A second aspect of the present invention provides a negative electrode sheet, the negative electrode sheet comprising a substrate and a polymer layer disposed on the substrate;

[0010] The polymer layer includes the covalent organic polymer described in the present invention.

[0011] The third aspect of the present invention provides a method for preparing the negative electrode sheet of the present invention, the method comprising: coating a solution containing a covalent organic polymer onto a surface of a substrate, and drying;

[0012] or

[0013] 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;

[0014] 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;

[0015] M for M 1 、M 2 or M 3 .

[0016] 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.

[0017] The 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;

[0018] The polymer layer includes the covalent organic polymer described in the present invention.

[0019] Through the above technical solution, the covalent organic polymer of the present invention is used in zinc ion batteries and alkaline zinc-based flow batteries, which can effectively inhibit the growth of zinc dendrites, thereby extending the life of the zinc negative electrode. It is speculated that the special skeleton structure formed by the covalent organic polymer of 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

[0020] Figure 1 ;

[0021] Figure 2 ;

[0022] Figure 3 picture;

[0023] Figure 4 SEM image of the electrode protected by the covalent organic polymer after cycling in Example 1;

[0024] Figure 5 ;

[0025] Figure 6 ;

[0026] Figure 7 SEM image of the bare zinc foil negative electrode of Comparative Example 1 after cycling.

[0027] Figure 8 The covalent organic polymer prepared in Example 1 13 C solid-state NMR spectroscopy. DETAILED DESCRIPTION

[0028] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0029] In one aspect, the present invention provides an application of a covalent organic polymer in inhibiting the growth of dendrites at the negative electrode of a flow battery or an ion battery. The covalent organic polymer has one or more of the structural units shown in formula (1), formula (2) and formula (3);

[0030]

[0031]

[0032] In formula (1), formula (2) and formula (3), n is each independently an integer of 1 to 10;

[0033] M 1 、M 2 、M 3 Each is independently selected from one or more of Group VIII, IIB and IVA metal elements.

[0034] According to a preferred embodiment of the present invention, M 1 、M 2 、M 3 Each is independently selected from one or more of Zn, Ni, Co, Fe and Sn, preferably Zn.

[0035] In the present invention, the covalent organic polymer is tested by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, and X-ray photoelectron spectroscopy (XPS) to determine the structural unit of the covalent organic polymer, refer 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 using a Burker 400M spectrometer. 3 C solid-state nuclear magnetic resonance spectroscopy illustrates the structure of the covalent organic polymer of the present invention.

[0036] 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:

[0037] 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;

[0038] 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;

[0039] M for M 1 、M 2 or M 3 .

[0040] 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.

[0041] 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.

[0042] According to a preferred embodiment of the present invention, in the solution, the concentration of 1,2,4,5-tetracyanobenzene is 0.1-10 mol / L.

[0043] According to a preferred embodiment of the present invention, the microwave reaction conditions include: temperature of 120-200°C, time of 5min-4h; microwave power of 300-600W.

[0044] 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 h.

[0045] 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.

[0046] A second aspect of the present invention provides a negative electrode sheet, the negative electrode sheet comprising a substrate and a polymer layer disposed on the substrate;

[0047] The polymer layer includes the covalent organic polymer described in the present invention.

[0048] In the present invention, there is no particular limitation on the type of the substrate. Materials used as negative electrodes for liquid flow batteries or as negative electrodes for aqueous zinc ion batteries 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] In the present invention, the covalent organic polymer can be loaded onto the surface of the base 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:

[0054] Coating loading: coating a solution containing a covalent organic polymer onto a substrate surface and drying; or

[0055] In-situ growth loading: contacting the substrate with a solution containing ions of the metal element M, 1,2,4,5-tetracyanobenzene and diamine nitrogen heterocyclic compounds, performing microwave reaction, separating, and drying the solid;

[0056] 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;

[0057] M for M 1 、M 2 or M 3 .

[0058] 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.

[0059] According to a preferred embodiment of the present invention, the solution containing the covalent organic polymer further contains a binder.

[0060] 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.

[0061] 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.

[0062] 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 diamine nitrogen heterocyclic compound, the molar ratio of 1,2,4,5-tetracyanobenzene to the diamine nitrogen heterocyclic compound is 1:0.1-10.

[0063] 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.

[0064] 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 diamine nitrogen heterocyclic compounds, the concentration of 1,2,4,5-tetracyanobenzene is 0.1-10 mol / L.

[0065] 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 300-600W.

[0066] 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 h.

[0067] According to a preferred embodiment of the present invention, in the solution containing ions of M metal element, 1,2,4,5-tetracyanobenzene and diamine nitrogen heterocyclic compound, the solvent is selected from one or more of C1-C6 alcohol, N,N-dimethylformamide and N,N-dimethylacetamide, preferably one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

[0068] 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.

[0069] 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.

[0070] In the present invention, the zinc-based liquid flow battery may or may not contain a separator, and is preferably a zinc-based liquid flow battery without a separator.

[0071] In the present invention, the zinc-based flow battery can be a single flow battery or a dual flow battery.

[0072] 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.

[0073] According to a preferred embodiment of the present invention, the electrolyte comprises: a solvent, a monovalent cation hydroxide, and a zinc ion source.

[0074] According to a preferred embodiment of the present invention, in the electrolyte, the concentration of the monovalent cation hydroxide is 1-10 mol / L.

[0075] 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.

[0076] 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 C1C4 alcohol, ethylene glycol, acetic acid and glycerol.

[0077] 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.

[0078] 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.

[0079] The 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;

[0080] 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.

[0081] 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 zinc sulfate (ZnSO 4 ), zinc trifluoromethanesulfonate (Zn(CF 3 SO 3 ) 2 ), zinc chloride (ZnCl 2 ), zinc nitrate (ZnNO 3 ) One or more; preferably, the concentration of the electrolyte is 0.1-3M.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] According to a preferred embodiment of the present invention, the polymer layer further comprises a binder.

[0086] According to a preferred embodiment of the present invention, the mass ratio of the covalent organic polymer to the binder is 8-9:1.

[0087] According to a preferred embodiment of the present invention, the binder is selected from polyvinyl pyrrolidone and / or polyvinylidene fluoride.

[0088] 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.

[0089] Example 1

[0090] (1) Synthesis of covalent organic polymers: 0.1 mol of 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 metal salt zinc chloride was dissolved in 10 ml of ethylene glycol as solution B, wherein 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;

[0091] (2) Solution C was placed in a microwave reactor, and the microwave power was controlled to be 300 W, the reaction temperature to be 180° C., and the reaction time to be 10 min. After the reaction was completed, the solution was washed with deionized water until it was neutral, and then dried at 60° C. for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in FIG. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M 1 For Zn. valent organic polymer 13 C solid-state NMR spectra Figure 8 shown.

[0092] (3) Preparation of covalent organic polymer slurry: The covalent organic matter 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.

[0093] (4) Coating of covalent organic polymer: The covalent organic polymer slurry solution D is uniformly coated on the zinc foil by a scraping method. The thickness of the zinc foil is 0.1 mm, and the thickness of the scraped covalent organic polymer is 50 μm. The coated zinc electrode is vacuum dried to remove the solvent. The drying temperature is 100° C. and the drying time is 6 h. After drying, a zinc negative electrode protected by a covalent organic polymer is obtained.

[0094] The cross-sectional SEM image of the zinc anode protected by the 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.

[0095] Symmetrical battery assembly: The symmetric battery was assembled in a standard CR2032 button cell. The battery was assembled in the order of covalent organic polymer-protected zinc electrode, separator (glass fiber separator, Whatman, GF / A), covalent organic polymer-protected zinc electrode, and 2M ZnSO 4 Electrolyte. At 3mA cm -2 Symmetrical battery cycle stability test was carried out under the conditions of

[0096] Test results: Figure 3 As shown in the figure, it is shown that the zinc anode protected by the covalent organic polymer can -2 The deposition and peeling was stable for more than 1300 hours under the conditions, and the electrode sheet after the cycle was further observed by SEM, such as Figure 4 As shown, no obvious growth of zinc dendrites was found.

[0097] Example 2

[0098] (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, wherein 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, wherein the concentration of the tin ion in solution B was 0.1 M. Solutions A and B were mixed uniformly by ultrasonication for 15 min to obtain solution C.

[0099] (2) Place solution C in a microwave reactor, control the microwave power to 300 W, the reaction temperature to 180° C., and the reaction time to 30 min. After the reaction is completed, wash the solution with deionized water and then dry it at 60° C. for 6 h to obtain a covalent organic polymer. The covalent organic polymer has a structural unit as shown in formula (1), wherein M 1 For Sn.

[0100] (3) Preparation of covalent organic polymer slurry: The covalent organic matter 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, the stirring temperature was 80°C and the stirring time was 6 h.

[0101] (4) Coating of covalent organic polymer: The covalent organic polymer slurry solution D is uniformly coated on the zinc metal foil by a scraping method. The thickness of the metal foil is 0.5 mm, and the thickness of the scraped covalent organic polymer is 10 μm. The coated zinc electrode is vacuum dried to remove the solvent. The drying temperature is 60° C. and the drying time is 6 h. After drying, a metal negative electrode protected by a covalent organic polymer is obtained.

[0102] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, and diaphragm (1cm 2 The microporous diaphragm, PP material), positive electrode sheet, positive current collector, and end plate support are assembled into a zinc-nickel single flow battery (the conductive surfaces of the negative current collector and the positive current collector are 5.8mm apart). The electrolyte flows in the battery in a "bottom-in and top-out" manner, with an electrolyte flow rate of 70L / h. The electrolyte is 8M KOH 0.6M ZnO.

[0103] Test conditions: 1C is used as the constant current density for charge and discharge, the battery is charged and discharged at a rate of 1C, the charging time is 1 hour, and the discharge cut-off voltage is 0.8V. Test end condition: When the battery capacity retention rate is lower than 60%, it is considered that the stable capacity cannot be maintained and the test is terminated.

[0104] Test results:

[0105] The assembled zinc-nickel flow battery can stably charge and discharge for 100 cycles.

[0106] Example 3

[0107] (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, wherein the concentration of the organic ligand was 0.1 M. 0.01 mol of ferric chloride was dissolved in ethylene glycol as solution B, wherein the concentration of Fe ions in solution B was 0.1 M. Solutions A and B were mixed by ultrasonication for 15 min to obtain solution C.

[0108] (2) Place solution C in a microwave reactor, control the microwave power to 600 W, the reaction temperature to 120° C., and the reaction time to 1 h. After the reaction is completed, wash the solution with deionized water and then dry it at 60° C. for 6 h to obtain a covalent organic polymer. The covalent organic polymer has a structural unit as shown in formula (2), wherein M 2 For Fe.

[0109] (3) Preparation of covalent organic polymer slurry: The covalent organic matter 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.

[0110] (4) Coating of covalent organic polymer: The covalent organic polymer slurry solution D is uniformly coated on the zinc foil by a doctor blade method. The thickness of the zinc foil is 0.1 mm, and the thickness of the covalent organic polymer is 100 μm. The coated zinc electrode is vacuum dried to remove the solvent. The drying temperature is 100° C. and the drying time is 6 h. After drying, a zinc negative electrode protected by a covalent organic polymer is obtained.

[0111] Symmetrical battery assembly: The symmetric battery was assembled in a standard CR2032 button cell. The battery was assembled in the order of covalent organic polymer-protected zinc electrode, separator (glass fiber separator, Whatman, GF / A), covalent organic polymer-protected zinc electrode, and 2M ZnSO 4 Electrolyte. At 3mAcm -2 Symmetrical battery cycle stability test was carried out under the conditions of

[0112] Test results: at 3mA cm -2 Stable deposition and stripping conditions for 1100 hours.

[0113] Example 4

[0114] (1) Synthesis of covalent organic polymers: 0.1 mol of organic ligand 1,2,4,5-tetracyanobenzene and 0.01 mol of 2,6-diaminopyridine were dissolved in N,N-dimethylformamide as solution A, wherein the concentration of the organic ligand was 1 M. 0.02 mol of cobalt chloride was dissolved in ethylene glycol as solution B, wherein the concentration of Co ions in solution B was 0.1 M. Solutions A and B were mixed uniformly by ultrasonication for 15 min to obtain solution C.

[0115] (2) The carbon felt was immersed in solution C and placed in a microwave reactor, and the microwave power was controlled to be 300 W, the reaction temperature was 200° C., and the reaction time was 40 min. After the reaction, the solution was washed with deionized water and then dried at 60° C. for 6 h to obtain a carbon felt modified with a covalent organic polymer through in situ growth. The covalent organic polymer has a structural unit as shown in formula (3), wherein M 3 For Co.

[0116] (3) The carbon felt electrode on which the covalent organic polymer is grown is subjected to vacuum drying to remove the solvent at a drying temperature of 60° C. for a drying time of 6 h. After drying, a carbon felt negative electrode protected by the covalent organic polymer is obtained.

[0117] 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 2The microporous diaphragm, PP material), positive electrode sheet, positive current collector, and end plate support are assembled into a zinc-nickel single flow battery (the conductive surfaces of the negative current collector and the positive current collector are 5.8mm apart). The electrolyte flows in the battery in a "bottom-in and top-out" manner, with an electrolyte flow rate of 70L / h. The electrolyte is 8M KOH 0.6M ZnO.

[0118] Test conditions: 1C is used as the constant current density for charge and discharge, the battery is charged and discharged at a rate of 1C, the charging time is 1 hour, and the discharge cut-off voltage is 0.8V. Test end condition: When the battery capacity retention rate is lower than 60%, it is considered that the stable capacity cannot be maintained and the test is terminated.

[0119] Test results:

[0120] The assembled zinc-nickel flow battery can stably charge and discharge for 90 cycles.

[0121] Example 5

[0122] (1) Synthesis of covalent organic polymers: 0.1 mol of 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, wherein the concentration of Fe ions in solution B was 0.1 M; solution A and solution B were ultrasonically mixed for 15 min to obtain solution C;

[0123] (2) Solution C was placed in a microwave reactor, and the microwave power was controlled to be 300 W, the reaction temperature to be 180° C., and the reaction time to be 10 min. After the reaction was completed, the solution was washed with deionized water until it was neutral, and then dried at 60° C. for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in FIG. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M 1 For Fe.

[0124] (3) Preparation of covalent organic polymer slurry: The covalent organic matter 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.

[0125] (4) Coating of covalent organic polymer: The covalent organic polymer slurry solution D is uniformly coated on the zinc foil by a doctor blade method. The thickness of the zinc foil is 0.1 mm, and the thickness of the covalent organic polymer is 100 μm. The coated zinc electrode is vacuum dried to remove the solvent. The drying temperature is 100° C. and the drying time is 6 h. After drying, a zinc negative electrode protected by a covalent organic polymer is obtained.

[0126] Symmetrical battery assembly: The symmetric battery was assembled in a standard CR2032 button cell. The battery was assembled in the order of covalent organic polymer-protected zinc electrode, separator (glass fiber separator, Whatman, GF / A), covalent organic polymer-protected zinc electrode, and 2M ZnSO 4 Electrolyte. At 3mAcm -2 Symmetrical battery cycle stability test was carried out under the conditions of

[0127] Test results: at 3mA cm -2 Stable deposition and stripping conditions for 1000 hours.

[0128] Example 6

[0129] (1) Synthesis of covalent organic polymers: 0.1 mol of 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 metal salt zinc chloride was dissolved in 10 ml of ethylene glycol as solution B, wherein 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;

[0130] (2) Solution C was placed in a microwave reactor, and the microwave power was controlled to be 300 W, the reaction temperature to be 180° C., and the reaction time to be 10 min. After the reaction was completed, the solution was washed with deionized water until it was neutral, and then dried at 60° C. for 6 h to obtain a covalent organic polymer. The SEM image of the covalent organic polymer is shown in FIG. Figure 1 As shown, the covalent organic polymer has a structural unit as shown in formula (1), wherein M 1 For Zn.

[0131] (3) Preparation of covalent organic polymer slurry: The covalent organic matter 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, the stirring temperature was 80°C and the stirring time was 6 h.

[0132] (4) Coating of covalent organic polymer: The covalent organic polymer slurry solution D is uniformly coated on the zinc metal foil by a scraping method. The thickness of the metal foil is 0.5 mm, and the thickness of the scraped covalent organic polymer is 10 μm. The coated zinc electrode is vacuum dried to remove the solvent. The drying temperature is 60° C. and the drying time is 6 h. After drying, a metal negative electrode protected by a covalent organic polymer is obtained.

[0133] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, and diaphragm (1cm2 The microporous diaphragm, PP material), positive electrode sheet, positive current collector, and end plate support are assembled into a zinc-nickel single flow battery (the conductive surfaces of the negative current collector and the positive current collector are 5.8mm apart). The electrolyte flows in the battery in a "bottom-in and top-out" manner, with an electrolyte flow rate of 70L / h. The electrolyte is 8M KOH 0.6M ZnO.

[0134] Test conditions: 1C is used as the constant current density for charge and discharge, the battery is charged and discharged at a rate of 1C, the charging time is 1 hour, and the discharge cut-off voltage is 0.8V. Test end condition: When the battery capacity retention rate is lower than 60%, it is considered that the stable capacity cannot be maintained and the test is terminated.

[0135] Test results:

[0136] The assembled zinc-nickel flow battery can stably charge and discharge for 120 cycles.

[0137] Example 7

[0138] (1) Synthesis of covalent organic polymers: 0.1 mol of 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 metal salt zinc chloride was dissolved in 10 ml of ethylene glycol as solution B, wherein 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;

[0139] (2) A zinc metal foil (thickness of 0.5 mm) was immersed in solution C and placed in a microwave reactor. The microwave power was controlled to be 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 zinc metal foil modified with a covalent organic polymer was obtained by in situ growth. The covalent organic polymer has a structural unit as shown in formula (1), wherein M 1 For Zn.

[0140] (3) The zinc metal foil electrode on which the covalent organic polymer is grown is subjected to vacuum drying to remove the solvent, the drying temperature is 60° C., and the drying time is 6 h. After drying, a zinc metal foil negative electrode protected by the covalent organic polymer is obtained.

[0141] Assembly of zinc-nickel flow battery: from left to right, follow the end plate support, negative electrode current collector, negative electrode sheet, and diaphragm (1cm 2The microporous diaphragm, PP material), positive electrode sheet, positive current collector, and end plate support are assembled into a zinc-nickel single flow battery (the conductive surfaces of the negative current collector and the positive current collector are 5.8mm apart). The electrolyte flows in the battery in a "bottom-in and top-out" manner, with an electrolyte flow rate of 70L / h. The electrolyte is 8M KOH 0.6M ZnO.

[0142] Test conditions: 1C is used as the constant current density for charge and discharge, the battery is charged and discharged at a rate of 1C, the charging time is 1 hour, and the discharge cut-off voltage is 0.8V. Test end condition: When the battery capacity retention rate is lower than 60%, it is considered that the stable capacity cannot be maintained and the test is terminated.

[0143] Test results:

[0144] The assembled zinc-nickel flow battery can stably charge and discharge for 128 cycles.

[0145] Comparative Example 1

[0146] 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 instead of the zinc electrode protected by the covalent organic polymer as the negative electrode plate, and the other conditions were the same as those of Example 1.

[0147] Symmetrical battery cycling stability test, at 2 mAh cm -2 Stable deposition and stripping under conditions.

[0148] Test results:

[0149] like Figure 6 As shown in the figure, the zinc anode without covalent organic polymer protection has a -2 Under these conditions, the deposition and peeling can only be stably carried out for less than 100 hours. Further SEM observations were performed on the electrode sheets after the cycles (e.g. Figure 7 (as shown), obvious wrinkles and irregular dendrites were found on the surface of the zinc electrode.

[0150] Comparative Example 2

[0151] The liquid flow battery is assembled according to the method of Example 2, except that zinc foil (the thickness of the zinc foil is 0.5 mm) is used instead of the zinc electrode protected by the covalent organic polymer as the negative electrode, and the other conditions are the same as those of Example 2.

[0152] Test conditions: 1C is used as the constant current density for charging and discharging, the battery is charged and discharged at a rate of 1C, the charging time is 1 hour, and the discharge cut-off voltage is 0.8V.

[0153] Test results:

[0154] The assembled zinc-nickel flow battery can only stably charge and discharge for 20 cycles.

Claims

1. A use of a covalent organic polymer in 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 of the structural units shown in formula (1), formula (2) and formula (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, preferably Zn.

3. 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.

4. The use according to claim 3, 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.

5. The use according to claim 3, wherein: The microwave reaction conditions include: temperature of 120-200°C, time of 5 min-4 h; microwave power of 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, preferably one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

6. 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 of any one of claims 1-5.

7. The negative electrode sheet according to claim 6, wherein: 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; Preferably, the thickness of the substrate is not higher than 50 mm, preferably 0.1-20 mm; and / or The thickness of the polymer layer is not higher than 200 μm, preferably 10-100 μm.

8. The negative electrode sheet according to claim 6 or 7, wherein: The content of the covalent organic polymer is 90-95wt% of the mass of the polymer layer; Preferably, 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.

9. The method for preparing a negative electrode sheet according to any one of claims 6 to 8, characterized in that: The method includes: applying a solution containing a covalent organic polymer onto a substrate surface and drying; Preferably, the solution containing the covalent organic polymer further contains a binder; Preferably, 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; Preferably, 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.

10. The preparation method according to claim 9, wherein: In a solution containing ions of 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; 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; and / or The microwave reaction conditions include: temperature of 120-200°C, time of 5 min-4 h; microwave power of 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, preferably one or more of ethanol, ethylene glycol, N,N-dimethylformamide and N,N-dimethylacetamide.

11. A zinc-based flow battery, comprising: A negative electrode, a positive electrode and an electrolyte, wherein the negative electrode is the negative electrode sheet according to any one of claims 6 to 8.

12. 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 of any one of claims 1-5.

13. The zinc ion battery according to claim 12, wherein: In the electrolyte, the electrolyte is selected from one or more of zinc sulfate, zinc trifluoromethanesulfonate, zinc chloride, and zinc nitrate; preferably, the concentration of the electrolyte is 0.1-3M; and / or The thickness of the zinc foil is not more than 50 mm, preferably 0.1-20 mm; and / or The thickness of the polymer layer is not higher than 200 μm, preferably 10-100 μm; and / or The content of the covalent organic polymer is 80-95wt% of the mass of the polymer layer; Preferably, 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.

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