Complexing agent, solid-phase bromine positive electrode active material, preparation method thereof and solid-phase bromine positive electrode and zinc-bromine battery

Abstract

The application provides a complexing agent, a solid-phase bromine positive electrode active material and a preparation method and a solid-phase bromine positive electrode and a zinc-bromine battery, and belongs to the technical field of energy storage batteries. n H 2n+2‑m X m )R m ; wherein 1<=n<=8, 2<=m<=4, m and n are integers; X is independently selected from any one of chlorine, bromine and iodine when multiple Xs exist; and R is independently selected from any one of a nitrogen-containing five-membered ring and a nitrogen-containing six-membered ring when multiple Rs exist.

Description

Technical Field

[0001] This invention belongs to the field of energy storage battery technology, specifically relating to a complexing agent, a solid-phase bromine positive electrode active material and its preparation method, as well as a solid-phase bromine positive electrode and a zinc-bromine battery. Background Technology

[0002] Renewable energy sources, such as wind and solar power, play a crucial role in future smart grids, effectively mitigating pollution from traditional fossil fuels and their own energy scarcity. However, renewable energy is subject to environmental limitations, exhibiting intermittency and randomness, necessitating energy storage devices for frequency regulation and energy storage. Rechargeable batteries, as energy storage devices, offer advantages such as low cost, lack of geographical limitations, and short investment cycles, making them a focus of attention in large-scale energy storage.

[0003] Aqueous zinc-bromine batteries are strong contenders for next-generation large-scale energy storage batteries due to their low cost, lack of pollution, high safety, and stability. However, traditional zinc-bromine flow batteries suffer from numerous problems that limit their large-scale adoption. For example, bromide ion diffusion leads to cross-contamination between the positive and negative electrodes; the use of expensive ion exchange membranes increases battery costs; and the zinc negative electrode is susceptible to side reactions, resulting in poor stability, reduced battery efficiency and cycle stability. Furthermore, it increases the maintenance costs of the flow circulation system, thus raising overall battery costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a complexing agent, a solid-phase bromine positive electrode active material, a method for preparing the same, a solid-phase bromine positive electrode, and a zinc-bromine battery, aiming to at least partially solve the above-mentioned technical problems. The specific technical solutions provided by this invention are as follows.

[0005] As a first aspect of the present invention, a complexing agent is provided having the structure shown in formula (a):

[0006] (C n H 2n+2-m X m )R m (one);

[0007] Where 1≤n≤8, 2≤m≤4, and m and n are both integers; when there are multiple X, each is independently selected from chlorine, bromine, and iodine; when there are multiple R, each is independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings.

[0008] As a second aspect of the present invention, a method for preparing the above-mentioned complexing agent is provided, comprising: mixing a nitrogen-containing heterocyclic compound and a haloalkane and then performing a first complexing reaction to obtain the complexing agent; wherein the nitrogen-containing heterocyclic compound includes at least one of a nitrogen-containing five-membered ring and a nitrogen-containing six-membered ring; and the haloalkane includes chlorine-, bromine-, or iodine-substituted C-type compounds. 1-8 At least one of the alkanes.

[0009] As a third aspect of the present invention, a solid-phase bromine positive electrode active material is provided, which is prepared using the above-mentioned complexing agent and has the structure shown in formula (II):

[0010] [(C n H 2n+2-m X m )R m ]Br a m (two);

[0011] Wherein, 1≤n≤8, 2≤m≤4, m and n are integers, and a is 2, 4 or 6; when there are multiple X, each is independently selected from chlorine, bromine, and iodine; when there are multiple R, each is independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings; nitrogen-containing five-membered rings include one or more of pyrrole, methylpyrrole, ethylpyrrole, pyrrolidine, methylpyrridine, ethylpyrridine, imidazole, methylimidazolium, ethylimidazolium, pyrazole, methylpyrazole, and ethylpyrazole; nitrogen-containing six-membered rings include one or more of pyridine, methylpyridine, ethylpyridine, piperidine, methylpiperidine, ethylpiperidine, pyrimidine, methylpyrimidine, and ethylpyrimidine.

[0012] As a fourth aspect of the present invention, a method for preparing the above-mentioned solid-phase bromine cathode active material is provided, comprising: mixing the above-mentioned complexing agent with elemental bromine or a first bromine salt and then carrying out a second complexing reaction to obtain the solid-phase bromine cathode active material.

[0013] As a fifth aspect of the present invention, a solid-phase bromine cathode is provided, comprising: the above-mentioned solid-phase bromine cathode active material, a conductive agent, a binder, and a current collector; wherein the solid-phase bromine cathode active material, the conductive agent, and the binder are uniformly mixed and loaded on the surface of the current collector; the mass ratio of the solid-phase bromine cathode active material, the conductive agent, and the binder is 7:1-2:0.5-1.

[0014] As a sixth aspect of the present invention, a zinc-bromine battery is provided, comprising: the above-described solid-phase bromine positive electrode, zinc negative electrode, and an aqueous electrolyte located between the solid-phase bromine positive electrode and the zinc negative electrode; wherein the zinc negative electrode is any one of zinc foil, pre-galvanized zinc-loving current collector, and zinc powder-loaded current collector; and the aqueous electrolyte is a second bromine salt, a zinc salt, or a mixed electrolyte of the second bromine salt, a zinc salt, and the above-described complexing agent.

[0015] Based on the above technical solutions, the complexing agent, solid-phase bromine positive electrode active material and its preparation method provided by the present invention, as well as the solid-phase bromine positive electrode and zinc-bromine battery, have at least one of the following beneficial effects.

[0016] (1) In the embodiments of the present invention, the complexing agent provided by the present invention has high symmetry and a more uniform distribution of its peripheral charge, making it easier to complex with bromine molecules to form a stable solid-phase bromine cathode active material. At the same time, the main chain carbon number of the complexing agent does not exceed 8, the molecular structure is relatively simple, and the relative molecular mass of the complexing agent is small. Therefore, it not only promotes the subsequent synthesis of a solid-phase bromine cathode with a high specific capacity, but also has better diffusivity. Thus, the synthesized solid-phase bromine cathode has excellent reaction kinetics.

[0017] (2) In the embodiments of the present invention, nitrogen-containing heterocyclic compounds and haloalkanes are used as raw materials to react via a hot solvent method to complex multiple nitrogen-containing heterocyclic compounds onto the haloalkanes, thereby obtaining a complexing agent with better symmetry and a more uniform distribution of peripheral charges. The method for preparing the synthetic complexing agent provided by the present invention does not require solvents or other additives, the preparation method is simple, and the requirements for equipment and reaction environment are low, making it suitable for industrial production.

[0018] (3) In the embodiments of the present invention, the present invention obtains a solid-phase bromine cathode active material by complexing multiple bromine molecules on a complexing agent. The complexing agent has multiple active adsorption sites for bromine, which can simultaneously bind multiple bromine molecules, increasing the mass proportion of active bromine element in the solid-phase bromine cathode active material, which is beneficial to improving the specific capacity of the bromine cathode. At the same time, the preparation method of the solid-phase bromine cathode active material provided by the present invention is simple and easy to implement, and is suitable for large-scale promotion.

[0019] (4) In an embodiment of the present invention, the solid-phase bromine cathode active material is mixed with a conductive agent and a binder and then directly loaded onto a current collector to obtain a solid-phase bromine cathode. Since multiple bromine molecules are complexed in the solid-phase bromine cathode active material, the solid-phase bromine cathode has a high bromine loading, and therefore the battery prepared using the solid-phase bromine cathode has a high specific capacity, areal capacity and energy density.

[0020] (5) In the embodiments of the present invention, the zinc-bromine battery provided by the present invention includes a solid-phase bromine positive electrode, a zinc negative electrode, and an electrolyte between the two. The positive electrode of the zinc-bromine battery undergoes a solid / liquid phase conversion reaction. The charging products in the positive electrode exist in a complexed form and will not diffuse to the negative electrode, causing corrosion of the zinc negative electrode, thereby improving the cycle stability of the zinc-bromine battery. Simultaneously, the solid-phase bromine positive electrode in the zinc-bromine battery provided by the present invention gives the zinc-bromine battery higher specific capacity, areal capacity, and energy density. Furthermore, since the solid-phase bromine positive electrode active material utilizes a novel complexing agent, the charging material in the zinc-bromine battery is solid, thus avoiding the use of ion exchange membranes, breaking the monopoly of ion exchange membranes. The cost of the zinc-bromine battery provided by the present invention will be one-tenth that of a traditional flow zinc-bromine battery. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the zinc-bromine battery reaction mechanism in an embodiment of the present invention;

[0022] Figure 2 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 68 mg / cm³. 2 Discharge curve at time;

[0023] Figure 3 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 68 mg / cm³. 2 Cyclic curve graph;

[0024] Figure 4 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 136 mg / cm³. 2 Discharge curve at time;

[0025] Figure 5 In Example 2 of this invention, the zinc-bromine battery has a positive electrode loading of 67 mg / cm³. 2 Discharge curve at time;

[0026] Figure 6 In Example 3 of this invention, the zinc-bromine battery has a positive electrode loading of 67 mg / cm³. 2 Discharge curve at time;

[0027] Figure 7 In Example 4 of this invention, the zinc-bromine battery has a positive electrode loading of 25 mg / cm³. 2 Discharge curve at time;

[0028] Figure 8 The discharge curve of the zinc-bromine battery in Comparative Example 1 of this invention is shown.

[0029] Figure 9 This is a cycle curve of the zinc-bromine battery in Comparative Example 1 of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0031] To address the pollution of the zinc anode caused by the diffusion of bromine positive electrode active material in traditional zinc-bromine flow batteries, and the high cost of batteries due to the use of expensive Nafion membranes, researchers have recently developed static zinc-bromine batteries using complexing agents. However, the complexing agents currently used in static zinc-bromine batteries have large molecular weights, resulting in low specific capacity and poor reversibility. Therefore, this invention provides a complexing agent with high symmetry and uniform peripheral charge distribution. Furthermore, the complexing agent provided by this invention has a main chain carbon number of no more than 8 and a relatively small molecular weight.

[0032] As a first aspect of the present invention, a complexing agent is provided having the structure shown in formula (a):

[0033] (C n H 2n+2-m X m )R m (one);

[0034] Where 1≤n≤8, 2≤m≤4, and m and n are both integers; when there are multiple X, each is independently selected from chlorine, bromine, and iodine; when there are multiple R, each is independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings.

[0035] In the embodiments of this invention, the complexing agent provided by this invention has high symmetry and a more uniform distribution of its peripheral charge, making it easier to complex with bromine molecules to form a stable solid-phase bromine cathode active material. Simultaneously, the complexing agent has no more than 8 carbon atoms in its main chain, a relatively simple molecular structure, and a small relative molecular mass. Therefore, it not only promotes a higher specific capacity in the subsequently synthesized solid-phase bromine cathode but also exhibits better diffusivity and superior electrode reaction kinetics in subsequent reactions.

[0036] Specifically, the complexing agent provided by the present invention has any one of the structures of formula (1) to formula (3):

[0037] Equation (1);

[0038] Equation (2);

[0039] Equation (3);

[0040] Where n is an integer between 1 and 8, X1, X2, X3, and X4 are each independently selected from chlorine, bromine, and iodine; R1, R2, R3, and R4 are each independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings.

[0041] According to embodiments of the present invention, the nitrogen-containing five-membered ring includes one or more of pyrrole, methylpyrrole, ethylpyrrole, pyrrolidine, methylpyrridine, ethylpyrridine, imidazole, methylimidazolium, ethylimidazolium, pyrazole, methylpyrazole, and ethylpyrazole; the nitrogen-containing six-membered ring includes one or more of pyridine, methylpyridine, ethylpyridine, piperidine, methylpiperidine, ethylpiperidine, pyrimidine, methylpyrimidine, and ethylpyrimidine.

[0042] Specifically, the complexing agent having the formula (1) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0043] Equation (1-1);

[0044] Equation (1-2);

[0045] Equation (1-3);

[0046] Equation (1-4);

[0047] Equation (1-5);

[0048] Equation (1-6);

[0049] Equation (1-7);

[0050] Equation (1-8).

[0051] Specifically, the complexing agent with formula (2) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0052] Equation (2-1);

[0053] Equation (2-2);

[0054] Equation (2-3).

[0055] Specifically, the complexing agent with formula (3) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0056] Equation (3-1);

[0057] Equation (3-2);

[0058] Equation (3-3);

[0059] Equation (3-4).

[0060] As a second aspect of the present invention, a method for preparing the above-mentioned complexing agent is provided, comprising: mixing a nitrogen-containing heterocyclic compound and a haloalkane and then performing a first complexing reaction to obtain the complexing agent; wherein the nitrogen-containing heterocyclic compound includes at least one of a nitrogen-containing five-membered ring and a nitrogen-containing six-membered ring; and the haloalkane includes chlorine-, bromine-, or iodine-substituted C-type compounds. 1-8 At least one of the alkanes.

[0061] In embodiments of the present invention, nitrogen-containing heterocyclic compounds and haloalkanes are reacted via a hot solvent method to complex multiple nitrogen-containing heterocyclic compounds onto the haloalkanes, resulting in a complexing agent with better symmetry and a more uniform distribution of peripheral charges. The method for preparing the synthetic complexing agent provided by the present invention requires no solvents or other additives, is simple to implement, and has low requirements for equipment and reaction environment, making it suitable for industrial production.

[0062] According to embodiments of the present invention, the molar ratio of the nitrogen-containing heterocyclic compound and the haloalkane is 2-4:1; the temperature of the first complexation reaction is 60-120°C, and the time of the first complexation reaction is 6-72 h; the nitrogen-containing five-membered ring includes one or more of pyrrole, methylpyrrole, ethylpyrrole, pyrrolidine, methylpyrridine, ethylpyrridine, imidazole, methylimidazolium, ethylimidazolium, pyrazole, methylpyrazole, and ethylpyrazole; the nitrogen-containing six-membered ring includes one or more of pyridine, methylpyridine, ethylpyridine, piperidine, methylpiperidine, ethylpiperidine, pyrimidine, methylpyrimidine, and ethylpyrimidine.

[0063] Specifically, the preparation method of the complexing agent provided by the present invention can be as follows: a nitrogen-containing heterocyclic compound is mixed with a haloalkane at a molar ratio of 2-4:1, sealed, and reacted at 60-120°C for 6-72 hours. After the reaction is complete, the mixture is washed 2-6 times with one or more of ethyl acetate, ethanol, methanol, and deionized water to remove unreacted salts and impurities. The mixture is then dried in an oven at 60-100°C for 2-12 hours to obtain the complexing agent.

[0064] In embodiments of the present invention, a complexing agent is prepared by hot solvent method using a nitrogen-containing heterocyclic compound and a haloalkane. The haloalkane can bind a corresponding number of nitrogen-containing heterocyclic compound molecules to form a complexing agent with a quaternary ammonium salt structure, and the structure of the complexing agent molecule maintains excellent symmetry. This is beneficial for the subsequent combination of the complexing agent and bromine molecules to form a solid bromine positive electrode active material. Each position in the aforementioned complexing agent corresponding to the quaternary ammonium salt compound contains a bromine active site, and each active site can complex one XBr2. - XBr4 - or XBr6 - The group, where X is a halogen, including Cl, Br, and I, can complex multiple bromine atoms to increase the mass proportion of bromine in the entire solid-phase bromine cathode active material, thereby improving the specific capacity of the subsequent solid-phase bromine cathode active material.

[0065] As a third aspect of the present invention, a solid-phase bromine positive electrode active material is provided, which is prepared using the above-mentioned complexing agent and has the structure shown in formula (II):

[0066] [(C n H 2n+2-m X m )R m ]Br a m (two);

[0067] Wherein, 1≤n≤8, 2≤m≤4, m and n are integers, and a is 2, 4 or 6; when there are multiple X, each is independently selected from chlorine, bromine, and iodine; when there are multiple R, each is independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings; nitrogen-containing five-membered rings include one or more of pyrrole, methylpyrrole, ethylpyrrole, pyrrolidine, methylpyrridine, ethylpyrridine, imidazole, methylimidazolium, ethylimidazolium, pyrazole, methylpyrazole, and ethylpyrazole; nitrogen-containing six-membered rings include one or more of pyridine, methylpyridine, ethylpyridine, piperidine, methylpiperidine, ethylpiperidine, pyrimidine, methylpyrimidine, and ethylpyrimidine.

[0068] In embodiments of the present invention, a solid-phase bromine positive electrode active material is obtained by complexing multiple bromine molecules onto a complexing agent. The complexing agent has multiple active adsorption sites for bromine, and can simultaneously bind multiple bromine molecules to form XBr2. - XBr4 - XBr6 - This increases the mass percentage of active bromine in the solid-phase bromine cathode active material.

[0069] Specifically, the solid-phase bromine positive electrode active material provided by the present invention has any one of the structures of formula (4) to formula (6):

[0070] Equation (4);

[0071] Equation (5);

[0072] Equation (6);

[0073] Where n is an integer between 1 and 8, and a is 2, 4 or 6; X1, X2, X3 and X4 are each independently selected from chlorine, bromine and iodine; R1, R2, R3 and R4 are each independently selected from nitrogen-containing five-membered rings and nitrogen-containing six-membered rings.

[0074] Specifically, the solid-phase bromine positive electrode active material with formula (4) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0075] Equation (4-1);

[0076] Equation (4-2);

[0077] Equation (4-3);

[0078] Equation (4-4);

[0079] Equation (4-5);

[0080] Equation (4-6);

[0081] Equation (4-7);

[0082] Equation (4-8).

[0083] Specifically, the solid-phase bromine positive electrode active material with formula (5) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0084] Equation (5-1);

[0085] Equation (5-2);

[0086] Equation (5-3).

[0087] Specifically, the solid-phase bromine positive electrode active material with formula (6) provided by the present invention includes, but is not limited to, any of the following specific structures:

[0088] Equation (6-1);

[0089] Equation (6-2);

[0090] Equation (6-3);

[0091] Equation (6-4).

[0092] As a fourth aspect of the present invention, a method for preparing the above-mentioned solid-phase bromine cathode active material is provided, comprising: mixing the above-mentioned complexing agent with elemental bromine or a first bromine salt and then carrying out a second complexing reaction to obtain the solid-phase bromine cathode active material.

[0093] In the embodiments of the present invention, the preparation method of the solid-phase bromine positive electrode active material provided by the present invention is simple and easy to implement, and is suitable for large-scale promotion.

[0094] According to an embodiment of the present invention, the second complexation reaction after mixing the above-mentioned complexing agent with elemental bromine or a first bromine salt includes: mixing the above-mentioned complexing agent and elemental bromine at a molar ratio of 1:2-12 and adding it to a solvent, reacting at room temperature for 5-60 min to obtain a solid-phase bromine positive electrode active material; or mixing the above-mentioned complexing agent and the first bromine salt at a molar ratio of 1:2-24 and adding it to water, and electroplating in a two-electrode system to obtain a solid-phase bromine positive electrode active material; wherein the solvent includes at least one of water, acetonitrile, ethanol, methanol, and N-methylpyrrolidone; and the first bromine salt includes at least one of ZnBr2, KBr, NaBr, NH4Br, and CaBr2.

[0095] Specifically, the solid-phase bromine cathode active material can be obtained by the following solvent reaction method: a complexing agent and elemental bromine are mixed in a molar ratio of 1:2-12 and added to a solvent. After reacting at room temperature for 5-60 min, the mixture is washed 2-6 times with the same solvent as during the reaction, filtered, and dried to obtain the solid-phase bromine cathode active material. The solvent includes at least one of water, acetonitrile, ethanol, methanol, and N-methylpyrrolidone; the concentration of the complexing agent is 0.1-10 mol / L; and the concentration of elemental bromine is 0.1-10 mol / L.

[0096] Specifically, solid-phase bromine cathode active material can be obtained by the following electroplating method: a complexing agent and a first bromine salt are mixed in a molar ratio of 1:2-24 and added to water, and electroplating is carried out in a two-electrode system to obtain the solid-phase bromine cathode active material. The working electrode and counter electrode in the two-electrode system are each independently selected from any one of graphite plate, graphite felt, platinum sheet, or gold-platinum; the concentration of the complexing agent is 0.1-10 mol / L; the first bromine salt includes at least one of ZnBr2, KBr, NaBr, NH4Br, and CaBr2, with a concentration of 0.1-20 mol / L. The electroplating current is 0.1-1000 mA / cm². 2 The electroplating time is 5-120 minutes.

[0097] As a fifth aspect of the present invention, a solid-phase bromine cathode is provided, comprising: the above-mentioned solid-phase bromine cathode active material, a conductive agent, a binder, and a current collector; wherein the solid-phase bromine cathode active material, the conductive agent, and the binder are uniformly mixed and loaded on the surface of the current collector; the mass ratio of the solid-phase bromine cathode active material, the conductive agent, and the binder is 7:1-2:0.5-1.

[0098] In an embodiment of the present invention, a solid-phase bromine cathode active material is mixed with a conductive agent and a binder and then directly loaded onto a current collector to obtain a solid-phase bromine cathode. Because multiple bromine molecules are complexed in the solid-phase bromine cathode active material, the solid-phase bromine cathode has a high bromine loading, and therefore, batteries prepared using the solid-phase bromine cathode have high specific capacity, areal capacity, and energy density.

[0099] Specifically, the solid-phase bromine cathode is obtained by the following method: a solid-phase bromine cathode active material, a conductive agent, and a binder are mixed in a suitable solvent at a mass ratio of 7:1-2:0.5-1, and then coated or dripped onto a current collector. After drying, the solid-phase bromine cathode is obtained. The conductive agent includes at least one of Ketjen black, activated carbon, multi-walled carbon nanotubes, carbon nanospheres, amorphous carbon, and graphene; the binder includes at least one of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE), and polyoxyethanol (PEO); the solvent includes at least one of water, methanol, ethanol, acetonitrile, and 1-methyl-2-pyrrolidone; and the current collector includes at least one of carbon felt, carbon cloth, carbon paper, carbon fiber, and titanium foil. The loading of the solid-phase bromine cathode active material on the current collector can be controlled between 5-300 mg / cm³. 2 Different load capacities can be obtained depending on different needs.

[0100] As a sixth aspect of the present invention, a zinc-bromine battery is provided, comprising: the above-described solid-phase bromine positive electrode, zinc negative electrode, and an aqueous electrolyte located between the solid-phase bromine positive electrode and the zinc negative electrode; wherein the zinc negative electrode is any one of zinc foil, pre-galvanized zinc-loving current collector, and zinc powder-loaded current collector; and the aqueous electrolyte is a second bromine salt, a zinc salt, or a mixed electrolyte of the second bromine salt, a zinc salt, and the above-described complexing agent.

[0101] In embodiments of the present invention, the zinc-bromine battery provided by the present invention includes a solid-phase bromine positive electrode, a zinc negative electrode, and an electrolyte between the two. The positive electrode of the zinc-bromine battery undergoes a solid / liquid phase conversion reaction. The charging products in the positive electrode exist in a complexed form and will not diffuse to the negative electrode, causing corrosion of the zinc negative electrode, thereby improving the cycle stability of the zinc-bromine battery. Simultaneously, the solid-phase bromine positive electrode in the zinc-bromine battery provided by the present invention gives the zinc-bromine battery higher specific capacity, areal capacity, and energy density. Furthermore, since the solid-phase bromine positive electrode active material utilizes a complexing agent, the charging material in the zinc-bromine battery is solid, thus avoiding the use of an ion exchange membrane, breaking the monopoly of ion exchange membranes. The cost of the zinc-bromine battery provided by the present invention is one-tenth that of a traditional flow zinc-bromine battery.

[0102] Specifically, the aqueous electrolyte in the zinc-bromine battery is a second bromide salt, a zinc salt, or a mixture of the second bromide salt, a zinc salt, and the aforementioned complexing agent. The second bromide salt includes ZnBr2, KBr, NaBr, MnBr2, BaBr2, CuBr2, MgBr2C4H. 12 BrN, C8H 10 BrN, C 12 H 28 BrN, C 16 H 36 At least one of BrN; zinc salts include ZnSO4, ZnCl2, Zn(NO3)2, ZnBr2, ZnI2, and Zn(CH3COO). 2、 At least one of Zn(CF3SO3)2; the concentrations of the second bromide salt and the zinc salt are both 0.01-20 mol / L; when the aqueous electrolyte contains the above complexing agent, the concentration of the complexing agent is 0.001-20 mol / L.

[0103] In the embodiments of the present invention, the zinc-bromine battery provided by the present invention can draw on the processes of lithium-ion batteries and lead-acid batteries that are currently industrially mature, thereby reducing manufacturing costs. In addition, the aqueous zinc-bromine battery has the characteristic of intrinsic safety, which can simplify the cost of the safety management system and facilitate its subsequent large-scale production and application.

[0104] According to embodiments of the present invention, the zinc-bromine battery described above includes any one of button batteries, cylindrical batteries, pouch batteries, prismatic batteries, and flow batteries.

[0105] The present invention will be further illustrated below through embodiments and related test experiments. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0106] Example 1

[0107] In Example 1, a complexing agent, 1,4-bis(pyridin-1-yl)butane dibromide (PCPBr2), was prepared, and a solid-phase bromine cathode active material, 1,4-bis(pyridin-1-yl)butane hexabromide (PCPBr6), and a solid-phase bromine cathode were prepared. The solid-phase bromine cathode was assembled into a zinc-bromine battery, and the electrochemical performance of the zinc-bromine battery was tested.

[0108] (1) Preparation of complexing agent 1,4-bis(pyridin-1-yl)butane dibromide (PCPBr2).

[0109] 10 mL of 1,4-dibromobutane and pyridine were placed in a round-bottom flask (molar ratio of 1,4-dibromobutane to pyridine was 1:2.5), stirred with a glass rod for 2 minutes, and then placed in a constant temperature oven at 80 °C for 48 hours. The flask was then removed, and the reaction product was transferred to a mortar and ground. Ethyl acetate was added to the ground sample and stirred thoroughly. The mixture was then centrifuged for 10 minutes in a high-speed centrifuge. The washing process was repeated three times. The obtained purified sample was then dried in an oven at 80 °C for 10 hours to obtain 1,4-bis(pyridin-1-yl)butane dibromide (PCPBr2) as shown in formula (I), i.e., the complexing agent PCPBr2.

[0110] Equation (Ⅰ).

[0111] (2) Preparation of solid-phase bromine cathode active material 1,4-bis(pyridin-1-yl)butane hexabromide (PCPBr6) and solid-phase bromine cathode.

[0112] PCPBr2 and elemental bromine were complexed in acetonitrile solution (the molar ratio of PCPBr2 to elemental bromine was 1:2) to obtain 1,4-bis(pyridin-1-yl)butane hexabromide (PCPBr6) as shown in formula (II), which is the solid-phase bromine positive electrode active material PCPBr6.

[0113] Formula (II).

[0114] Then, polyethylene oxide (PEO) and carbon black were added to the above solution and stirred for 8 hours, wherein the mass ratio of PCPBr6:carbon black:PEO was 7:2:1. The stirred slurry was coated onto the carbon felt current collector and dried in an oven for 6 hours to obtain a solid-phase bromine cathode.

[0115] (3) Preparation of zinc-bromine batteries.

[0116] The above solid-phase bromine positive electrode and zinc sheet negative electrode were assembled into a static zinc-bromine battery, with the electrolyte being 0.5 mol / L ZnBr2 and 0.1 mol / L PCPBr2.

[0117] (4) Electrochemical performance test of zinc-bromine battery.

[0118] Figure 1 This is a schematic diagram of the zinc-bromine battery reaction mechanism in an embodiment of the present invention.

[0119] A schematic diagram of the reaction mechanism of preparing a solid-phase bromine cathode using PCPBr6 as the solid-phase bromine cathode active material and assembling a zinc-bromine battery using it is shown below. Figure 1 As shown; and the reaction equations for the positive and negative electrodes, as well as their standard electrode potentials, are as follows:

[0120] Positive electrode: 6Br - +PCP 2+ -4e - PCPBr6(E 0 =1.08V),

[0121] Negative electrode: Zn 2+ +2e - Zn(E 0 =-0.76V),

[0122] Overall reaction: 6Br - +PCP 2+ +2Zn 2+ PCPBr6+2Zn (E=1.84V).

[0123] The aqueous zinc-bromine battery assembled with the above-mentioned solid-phase bromine cathode, zinc sheet anode, and electrolyte was subjected to charge-discharge and cycle performance tests at a current density of 10 mA / cm². 2 .

[0124] Figure 2 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 68 mg / cm³. 2 Discharge curve at time; Figure 3 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 68 mg / cm³. 2 Cyclic curve graph; Figure 4 In Example 1 of this invention, the zinc-bromine battery has a positive electrode loading of 136 mg / cm³. 2 The discharge curve at that time.

[0125] Combination Figure 2 and Figure 3 It can be seen that the solid-phase bromine cathode prepared in Example 1 has a specific capacity of 147 mAh / g and high cycle stability. Furthermore, under long-term cycling conditions, it maintains a coulombic efficiency of approximately 98% and an average discharge voltage of 1.7V. Additionally, the battery exhibits high areal capacity (10 mAh / cm²). 2 It can stably cycle for over 1400 times under these conditions. (Combined with...) Figure 4 It can be seen that when the loading of PCPBr6 on the solid-phase bromine cathode is increased to 130 mg, its areal capacity approaches 19 mAh / cm³. 2 Therefore, the solid-phase bromine cathode prepared in Example 1 exhibits high specific capacity, areal capacity, coulombic efficiency, and cycle stability in a static aqueous zinc-bromine battery.

[0126] Example 2

[0127] In Example 2, a complexing agent 1,4-bis(pyridin-1-yl)butane dibromide (PCPBr2) as shown in Formula (III) was prepared. The specific preparation method was the same as in Example 1, except that the reaction temperature in Example 2 was 60°C and the reaction time was 72 hours. Similarly, in Example 2, the obtained complexing agent PCPBr2 was used to prepare a solid-phase bromine cathode active material 1,4-bis(pyridin-1-yl)butane hexabromide (PCPBr6) as shown in Formula (IV) and a solid-phase bromine cathode. The solid-phase bromine cathode was assembled into a zinc-bromine battery, and the electrochemical performance of the zinc-bromine battery was tested. The specific preparation method, assembly method, and testing method were the same as in Example 1.

[0128] Formula (Ⅲ);

[0129] Formula (Ⅳ).

[0130] Figure 5 In Example 2 of this invention, the zinc-bromine battery has a positive electrode loading of 67 mg / cm³. 2 The discharge curve at that time.

[0131] Combination Figure 5 It can be seen that the zinc-bromine battery in Example 2 can achieve a concentration of 67 mg / cm³. 2 A specific capacity of approximately 138 mAh / g was obtained under the loading conditions, indicating that the complexing agent PCPBr2 was successfully synthesized under these conditions. Compared with Example 1, the slightly lower specific capacity indicates the presence of a small amount of impurities in the complexing agent PCPBr2 synthesized under the reaction conditions of Example 2 and in the solid-phase bromine cathode.

[0132] Example 3

[0133] In Example 3, a complexing agent 1,4-bis(imidazol-1-yl)butane dichloride complexing agent (ICICl2) as shown in Formula (V) was prepared. The specific preparation method was the same as in Example 1, except that the raw materials used in Example 3 were 1,4-dichlorobutane and imidazolium, the reaction temperature was 100°C, and the reaction time was 6 hours. Similarly, in Example 3, the obtained complexing agent ICICl2 was used to prepare a solid-phase bromine cathode active material 1,4-bis(imidazol-1-yl)butane dichlorotetrabromide (ICICl2Br4) as shown in Formula (VI) and a solid-phase bromine cathode. The solid-phase bromine cathode was assembled into a static zinc-bromine battery, wherein the electrolyte was 0.5 mol / L ZnBr2 and 0.1 mol / L ICICl2. The electrochemical performance of the zinc-bromine battery was tested, and the specific preparation method, assembly method, and testing method were the same as in Example 1.

[0134] Formula (V);

[0135] Formula (VI).

[0136] Figure 6 In Example 3 of this invention, the zinc-bromine battery has a positive electrode loading of 67 mg / cm³. 2 The discharge curve at that time.

[0137] Combination Figure 6 It can be seen that the zinc-bromine battery in Example 3 can achieve a concentration of 67 mg / cm³. 2 The specific capacity of approximately 170 mAh / g was obtained under a loading of chlorine, indicating that the complexing agent ICICl2 can also be successfully synthesized from chlorinated alkanes and has a high specific capacity.

[0138] Example 4

[0139] Example 4 prepared a complexing agent, 1,2,3,4-tetra(pyridin-1-yl)butane tetrabromide (PCPBr4), as shown in formula (VII). The specific preparation method was the same as in Example 1, except that the raw materials used in Example 4 were 1,2,3,4-tetrabromobutane and pyridine, with a molar ratio of 1:4. The reaction temperature was 90°C, and the reaction time was 72 hours. Similarly, Example 4 used the obtained complexing agent PCPBr4 to prepare a solid-phase bromine cathode active material, 1,2,3,4-tetra(pyridin-1-yl)butane eicosébromide (PCPBr4), as shown in formula (VIII). 20The zinc-bromine battery was assembled using a solid-phase bromine cathode and its electrochemical performance was tested. The specific preparation, assembly, and testing methods were the same as in Example 1, except that the molar ratio of PCPBr4 to elemental bromine was 1:8 when preparing the solid-phase bromine cathode active material, and the electrolyte was 0.5 mol / L ZnBr2 and 0.1 mol / L PCPBr4.

[0140] Formula (VII);

[0141] Formula (VIII).

[0142] Figure 7 In Example 4 of this invention, the zinc-bromine battery has a positive electrode loading of 25 mg / cm³. 2 The discharge curve at that time.

[0143] Combination Figure 7 It can be seen that polybrominated ions Br5 - Formed on a solid-phase bromine cathode, with a loading of 25 mg / cm³. 2 The solid-phase bromine cathode achieved a specific capacity of 206 mAh / g, indicating that the complexing agent PCPBr4 successfully complexed multiple bromine molecules and obtained a high specific capacity.

[0144] Comparative Example 1

[0145] Comparative Example 1 prepared a traditional solid-phase bromine cathode active material, tetrapropylammonium tribromide (TPABr3), and used it to prepare a solid-phase bromine cathode. The solid-phase bromine cathode was then assembled into a zinc-bromine battery, and the electrochemical performance of the zinc-bromine battery was tested.

[0146] (1) Preparation of solid-phase bromine cathode active material TPABr3 and solid-phase bromine cathode

[0147] Tetrapropylammonium bromide (TPABr) and elemental bromine were complexed in acetonitrile solution (molar ratio of TPABr to elemental bromine was 1:1) to obtain tetrapropylammonium tribromide (TPABr3) as shown in formula (IX), i.e., solid-phase bromine active material TPABr3. Then, PEO and carbon black were added to the above solution and stirred for 8 hours, wherein the mass ratio of TPABr3:carbon black:PEO was 7:2:1. The stirred slurry was coated onto a carbon felt current collector and dried in an oven for 6 hours to obtain a solid-phase bromine cathode.

[0148] Formula (IX).

[0149] (2) Preparation of zinc-bromine batteries.

[0150] The above solid-phase bromine positive electrode and zinc sheet negative electrode were assembled into a static zinc-bromine battery. The electrolyte was 0.5 mol / L ZnBr2 and 0.25 mol / L TPABr.

[0151] (3) Electrochemical performance test of zinc-bromine battery.

[0152] The reaction equations for preparing a solid-phase bromine cathode using TPABr3 as the active material and the reaction equations for the positive and negative electrodes of a zinc-bromine battery assembled using it, along with their standard electrode potentials, are as follows:

[0153] Positive electrode: 3Br - +TPA + -2e - TPABr3(E 0 =1.08V),

[0154] Negative electrode: Zn 2+ +2e - Zn(E 0 =-0.76V),

[0155] Overall reaction: 3Br - +TPA + +Zn 2+ TPABr+Zn (E=1.84V).

[0156] The aqueous zinc-bromine battery assembled with the above-mentioned solid-phase bromine cathode, zinc sheet anode, and electrolyte was subjected to charge-discharge and cycle performance tests at a current density of 10 mA / cm². 2 .

[0157] Figure 8 The discharge curve of the zinc-bromine battery in Comparative Example 1 of this invention is shown. Figure 9 This is a cycle curve of the zinc-bromine battery in Comparative Example 1 of the present invention.

[0158] contrast Figure 8 and Figure 2 It can be seen that the solid-phase bromine cathode prepared in Comparative Example 1 has a specific capacity of only 96 mAh / g and an average voltage of 1.55 V, which is lower than the solid-phase bromine cathode prepared in Example 1, which has 147 mAh / g and an average voltage of 1.7 V. From Figure 9 and Figure 3 The comparison shows that the zinc-bromine battery assembled using a solid-phase bromine cathode in Comparative Example 1 can only achieve a capacity of 10 mAh / cm³. 2 The solid-phase bromine cathode prepared in Example 1 exhibits stable cycling for 550 cycles at its areal capacity, lower than the 1400 cycles achieved by the zinc-bromine battery in Example 1. This comparative example demonstrates that the solid-phase bromine cathode prepared in Example 1 possesses high specific capacity, areal capacity, coulombic efficiency, and cycle stability.

[0159] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A complexing agent, wherein, The complexing agent has the structure shown in formula (V) or formula (VII): （Ⅴ）； （Ⅶ）。 2. A method for preparing the complexing agent as described in claim 1, comprising: A nitrogen-containing heterocyclic compound and a haloalkane are mixed and subjected to a first complexation reaction to obtain a complexing agent; The nitrogen-containing heterocyclic compound includes at least one of pyridine and imidazole; The haloalkane includes at least one of 1,4-dichlorobutane and 1,2,3,4-tetrabromobutane.

3. The method for preparing the complexing agent according to claim 2, wherein, The molar ratio of the nitrogen-containing heterocyclic compound to the haloalkane is 2-4:1; The temperature of the first complexation reaction is 60-120℃, and the time of the first complexation reaction is 6-72h.

4. A solid-phase bromine positive electrode active material, prepared using the complexing agent as described in claim 1, wherein, The solid-phase bromine positive electrode active material has the structure shown in formula (VI) or formula (VIII): （Ⅵ）； （Ⅷ）。 5. A method for preparing the solid-phase bromine positive electrode active material as described in claim 4, comprising: The complexing agent as described in claim 1 is mixed with elemental bromine or the first bromine salt and then subjected to a second complexing reaction to obtain a solid-phase bromine positive electrode active material.

6. The method for preparing the solid-phase bromine positive electrode active material according to claim 5, wherein, The second complexation reaction is carried out by mixing the complexing agent as described in claim 1 with elemental bromine or a first bromine salt, comprising: The complexing agent as described in claim 1 and elemental bromine are mixed in a molar ratio of 1:2-12 and added to a solvent, and reacted at room temperature for 5-60 min to obtain a solid-phase bromine positive electrode active material; or The complexing agent as described in claim 1 and the first bromide salt are mixed in a molar ratio of 1:2-24 and added to water, and electroplating is carried out in a two-electrode system to obtain a solid-phase bromine positive electrode active material. The solvent includes at least one of water, acetonitrile, ethanol, methanol, and N-methylpyrrolidone. The first bromine salt includes at least one of ZnBr2, KBr, NaBr, NH4Br, and CaBr2.

7. A solid-phase bromine cathode, comprising: Solid-phase bromine cathode active material, conductive agent, binder, current collector; The solid-phase bromine positive electrode active material, conductive agent, and binder are mixed evenly and loaded onto the surface of the current collector; The mass ratio of the solid-phase bromine positive electrode active material, conductive agent, and binder is 7:1-2:0.5-1; The solid-phase bromine cathode active material includes the solid-phase bromine cathode active material as described in claim 4, or a solid-phase bromine cathode active material having the structure shown in formula (II); （Ⅱ）； The solid-phase bromine positive electrode active material having the structure shown in formula (II) is prepared using a complexing agent having the structure shown in formula (I); （Ⅰ）。 8. A zinc-bromine battery, comprising: The solid-phase bromine positive electrode, the zinc negative electrode, and the aqueous electrolyte located between the solid-phase bromine positive electrode and the zinc negative electrode as described in claim 7; The zinc negative electrode is any one of zinc foil, pre-galvanized zinc-loving current collector, or zinc powder-loaded current collector; The aqueous electrolyte is a mixed electrolyte comprising a second bromide salt and a zinc salt, or a mixed electrolyte comprising a second bromide salt, a zinc salt and a complexing agent as described in claim 1, or a mixed electrolyte comprising a second bromide salt, a zinc salt and a complexing agent having the structure shown in formula (I); （Ⅰ）。 9. The zinc-bromine battery according to claim 8, wherein, The zinc-bromine battery includes any one of the following: button cell, cylindrical cell, pouch cell, prismatic cell, and flow cell.

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