An alkali metal ion-doped copper iron manganese cathode material and its preparation method

Abstract

The present invention discloses a field related to cathode materials, specifically an alkali metal ion-doped copper-iron-manganese cathode material and a preparation method thereof, which are used to solve the problems existing in the existing copper-iron-manganese-based cathode materials, such as easy agglomeration and uneven dispersion, resulting in poor cycle performance and electrochemical performance; in the process of preparing the alkali metal ion-doped copper-iron-manganese cathode material, a particle modifier is first prepared. The molecular structure of the particle modifier contains a large number of siloxanes, which can enhance the dispersion of active particles. At the same time, a large number of thiophene rings, pyrrole rings and cobalt ions doped by compounding are introduced, which can further improve its conductivity and also improve the conductivity, thereby enhancing the electrochemical performance of active particles. Moreover, the pyrrole ring can form a polymer with pyrrole to wrap the active particles, which not only protects and improves its cycle stability, but also enhances the conductivity of the formed polymer to further improve its electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the field of cathode materials, and particularly to an alkali metal ion-doped copper iron manganese cathode material and a preparation method thereof. Background Art

[0002] As a technology with high energy conversion efficiency, electrochemical energy storage has attracted wide attention. Especially the development of lithium-ion batteries has greatly changed our daily life. However, the uneven distribution and high price of raw materials for lithium-ion batteries limit their further development. Sodium-ion batteries are considered a competitive alternative because of their similar performance to lithium-ion batteries and the abundant sodium resources in the earth's crust, which can greatly reduce costs.

[0003] Cathode materials are considered the key to developing high-performance sodium-ion batteries. Sodium-ion battery copper iron manganese-based cathode materials have attracted extensive attention from researchers due to advantages such as rich raw materials, environmental friendliness, and good air stability. However, the existing copper iron manganese-based cathode materials are prone to agglomeration and uneven dispersion, resulting in poor cycle performance and electrochemical performance. Summary of the Invention

[0004] In order to overcome the above technical problems, the purpose of the present invention is to provide an alkali metal ion-doped copper iron manganese cathode material and a preparation method thereof: by adding copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide, and an ethanol solution to a three-necked flask and stirring for reaction to obtain a mixed ion solution, then adding a sodium hydroxide solution dropwise to the mixed ion solution, continuing to stir for reaction after dropping, cooling the reaction product to room temperature after the reaction, then vacuum filtering, washing and drying the filter cake to obtain a precursor, adding the precursor to a tube furnace for calcination, and then cooling with the furnace, and obtaining active particles after grinding, adding the active particles, a particle modifier, and an ethanol solution to a three-necked flask and stirring for reaction, then adding anhydrous ferric chloride and pyrrole and continuing to stir for reaction, vacuum filtering the reaction product after the reaction, washing and drying the filter cake to obtain the alkali metal ion-doped copper iron manganese cathode material, solving the problem that the existing copper iron manganese-based cathode materials are prone to agglomeration and uneven dispersion, resulting in poor cycle performance and electrochemical performance.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of an alkali metal ion-doped copper iron manganese cathode material, comprising the following steps:

[0007] Step 1: Add copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide, and ethanol solution into a three-necked flask equipped with a stirrer, a thermometer, and a constant-pressure dropping funnel. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 400 - 600 r / min to obtain a mixed ionic solution. Then, add the sodium hydroxide solution dropwise into the mixed ionic solution at a dropping rate of 1 - 2 drops / s. After the addition is complete, raise the temperature to 150 - 160 °C and continue to stir and react for 10 - 15 h. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Wash the filter cake with distilled water 3 - 5 times, and after drying, obtain a precursor;

[0008] Step 2: Add the precursor into a tube furnace, introduce argon for protection, and calcine at a heating rate of 2 - 3 °C / min to 450 - 470 °C for 4 - 5 h. Then, continue to heat up to 800 - 820 °C and calcine for 8 - 10 h. Then, cool with the furnace, and after grinding, obtain active particles;

[0009] Step 3: Add the active particles, particle modifier, and ethanol solution into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a reflux condenser. Introduce nitrogen for protection, stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 400 - 600 r / min. Then, raise the temperature to reflux and continue to stir and react for 3 - 5 h. Then, cool to 25 - 30 °C and add anhydrous ferric chloride and pyrrole. Then, continue to stir and react for 20 - 30 h. After the reaction is completed, perform vacuum filtration on the reaction product. Wash the filter cake with anhydrous methanol and distilled water 2 - 3 times in sequence, and then place it in a vacuum drying oven and dry at a temperature of 80 - 85 °C for 8 - 10 h to obtain the alkali metal ion-doped copper iron manganese cathode material.

[0010] The molecular structure of the alkali metal ion-doped copper iron manganese cathode material is as follows:

[0011]

[0012] As a further scheme of the present invention: The dosage ratio of the copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide, ethanol solution, and sodium hydroxide solution in Step 1 is 20 mmol: 10 mmol: 20 mmol: 0.15 - 0.25 g: 100 - 120 mL: 30 - 50 mL. The volume fraction of the ethanol solution is 50%, and the mass fraction of the sodium hydroxide solution is 35 - 40%.

[0013] As a further solution of the present invention: the dosage ratio of the active particles, particle modifier, ethanol solution, anhydrous ferric chloride, and pyrrole in step two is 10 g: 0.8 - 3.6 g: 60 - 80 mL: 2.6 - 5.2 g: 2.5 - 5.5 mL, and the volume fraction of the ethanol solution is 70 - 80%.

[0014] As a further solution of the present invention: the particle modifier is prepared by the following steps:

[0015] Step s1: Add 8-hydroxy-2-methylquinoline, dioxane, bromoethane, and anhydrous potassium carbonate into a three-necked flask equipped with a stirrer and a thermometer. Stir and react at a temperature of 60 - 65 °C and a stirring rate of 400 - 600 r / min for 20 - 25 h. After the reaction is completed, cool the reaction product to room temperature, then extract it with dichloromethane 2 - 3 times, then wash the extract with distilled water 3 - 5 times, then dry it with anhydrous magnesium sulfate, then perform vacuum filtration, and rotate and evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0016] The reaction principle is as follows:

[0017]

[0018] Step s2: Add selenium dioxide and dioxane into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a constant pressure dropping funnel. Stir and react at a temperature of 25 - 30 °C and a stirring rate of 400 - 600 r / min for 30 - 40 min, then gradually add the intermediate 1 solution dropwise while stirring, control the dropping rate to be 1 - 2 drops / s, and continue to stir and react under reflux conditions for 10 - 15 h after the addition is completed. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration, rotate and evaporate the filtrate to remove the solvent, and then perform recrystallization with dichloromethane to obtain intermediate 2;

[0019] The reaction principle is as follows:

[0020]

[0021] Step s3: Add intermediate 2 and pyrrole into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a constant pressure dropping funnel. Introduce nitrogen for protection. While stirring at a temperature of 20 - 25 °C and a stirring rate of 400 - 600 r / min, add trifluoroacetic acid drop by drop, controlling the dropping rate at 1 - 2 drops / s. After the addition is complete, continue stirring and reacting for 30 - 50 min. After the reaction ends, adjust the reaction product to pH 7 - 8 with sodium hydroxide solution, then extract it with dichloromethane 2 - 3 times. Then wash the extract with distilled water 3 - 5 times, dry it with anhydrous magnesium sulfate, then perform vacuum filtration. Rotate and evaporate the filtrate to remove the solvent, and then recrystallize it with anhydrous methanol to obtain intermediate 3;

[0022] The reaction principle is as follows:

[0023]

[0024] Step s4: Add intermediate 3, 4-bromo-2-thiophenecarboxaldehyde and dichloromethane into a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel. While stirring at a temperature of 25 - 30 °C and a stirring rate of 400 - 600 r / min, add trifluoroacetic acid drop by drop, controlling the dropping rate at 1 - 2 drops / s. After the addition is complete, continue stirring and reacting for 30 - 50 min. Then add p-chloranil and continue stirring and reacting for 8 - 10 h. After the reaction ends, perform vacuum filtration on the reaction product, and then rotate and evaporate the filtrate to remove the solvent to obtain intermediate 4;

[0025] The reaction principle is as follows:

[0026]

[0027] Step s5: Add intermediate 4, cobalt acetate and N,N-dimethylformamide into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser. Introduce nitrogen for protection. While stirring at a temperature of 25 - 30 °C and a stirring rate of 400 - 600 r / min, stir and react for 20 - 30 min. Then raise the temperature to reflux and continue stirring and reacting for 5 - 7 h. After the reaction ends, cool the reaction product to room temperature, then rotate and evaporate to remove the solvent. Then perform silica gel column chromatography on the evaporation product using the mixed solution as the eluent to obtain intermediate 5;

[0028] The reaction principle is as follows:

[0029]

[0030] Step s6: Add intermediate 5, pyrrole, anhydrous ether, and potassium tert-butoxide into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 7 - 9 h under the conditions of a temperature of 25 - 30°C and a stirring rate of 400 - 600 r / min. After the reaction is completed, pour the reaction product into ice water, then extract it with dichloromethane 2 - 3 times. Then wash the extract with distilled water 3 - 5 times, dry it with anhydrous magnesium sulfate, then perform vacuum filtration, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 6;

[0031] The reaction principle is as follows:

[0032]

[0033] Step s7: Add intermediate 7, tetrahydrofuran, and concentrated hydrochloric acid into a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. Stir and react for 20 - 30 min under the conditions of a temperature of 25 - 30°C and a stirring rate of 400 - 600 r / min. Then raise the temperature to reflux and continue to stir and react for 15 - 20 h. After the reaction is completed, cool the reaction product to room temperature, then let it stand for liquid separation, and rotary evaporate the organic phase to remove the solvent to obtain intermediate 7;

[0034] The reaction principle is as follows:

[0035]

[0036] Step s8: Add intermediate 7, γ-glycidoxypropyltrimethoxysilane, and anhydrous ethanol into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 3 - 5 h under the conditions of a temperature of 70 - 80°C and a stirring rate of 400 - 600 r / min. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent to obtain the particle modifier.

[0037] The reaction principle is as follows:

[0038]

[0039] As a further scheme of the present invention: The dosage ratio of 8-hydroxy-2-methylquinoline, dioxane, bromoethane, and anhydrous potassium carbonate in step s1 is 0.1 mol: 120 - 150 mL: 0.1 mol: 0.15 - 0.2 mol.

[0040] As a further scheme of the present invention: The dosage ratio of selenium dioxide, dioxane, and intermediate 1 solution in step s2 is 0.1 mol: 120 - 150 mL: 50 - 60 mL, and the intermediate 1 solution is a solution formed by dissolving intermediate 1 in dioxane according to 0.08 - 0.1 mol: 50 mL.

[0041] As a further solution of the present invention: the dosage ratio of the intermediate 2, pyrrole and trifluoroacetic acid in step s3 is 15-20 mL: 10 mmol: 1-1.5 mmol, and the mass fraction of the sodium hydroxide solution is 15-20%.

[0042] As a further solution of the present invention: the dosage ratio of the intermediate 3, 4-bromo-2-thiophenecarboxaldehyde, trifluoroacetic acid and p-chloranil in step s4 is 15-20 mmol: 10 mmol: 120-150 mL: 5-7 mmol: 5-7 mmol.

[0043] As a further solution of the present invention: the dosage ratio of the intermediate 4, cobalt acetate and N, N-dimethylformamide in step s5 is 10 mmol: 10 mmol: 80-100 mL, and the mixed solution is a mixture of chloroform and anhydrous methanol in a volume ratio of 5-6: 1.

[0044] As a further solution of the present invention: the dosage ratio of the intermediate 5, pyrrole, anhydrous ether and potassium tert-butoxide in step s6 is 10 mmol: 10 mmol: 80-100 mL: 10-15 mmol.

[0045] As a further solution of the present invention: the dosage ratio of the intermediate 7, tetrahydrofuran and concentrated hydrochloric acid in step s7 is 10 mmol: 50-60 mL: 30-40 mL, and the mass fraction of the concentrated hydrochloric acid is 37%.

[0046] As a further solution of the present invention: the dosage ratio of the intermediate 7, γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol in step s8 is 10 mmol: 35-40 mmol: 80-100 mL.

[0047] As a further solution of the present invention: an alkali metal ion-doped copper iron manganese cathode material, which is prepared according to the preparation method of the alkali metal ion-doped copper iron manganese cathode material.

[0048] The beneficial effects of the present invention:

[0049] An alkali metal ion-doped copper iron manganese cathode material and a preparation method thereof according to the present invention. Copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide and an ethanol solution are added to a three-necked flask and stirred to react to obtain a mixed ion solution. Then, a sodium hydroxide solution is added dropwise to the mixed ion solution. After the addition is completed, stirring is continued for reaction. After the reaction is completed, the reaction product is cooled to room temperature, and then vacuum filtration is carried out. The filter cake is washed and dried to obtain a precursor. The precursor is added to a tube furnace and calcined, and then cooled with the furnace. After grinding, active particles are obtained. The active particles, a particle modifier and an ethanol solution are added to a three-necked flask and stirred to react. Then, anhydrous ferric chloride and pyrrole are added and stirring is continued for reaction. After the reaction is completed, the reaction product is vacuum filtered. The filter cake is washed and dried to obtain the alkali metal ion-doped copper iron manganese cathode material; in this preparation method, copper sulfate pentahydrate, ferrous sulfate heptahydrate and manganese sulfate monohydrate are used as main raw materials for coprecipitation to form a precursor. Then, the precursor is calcined to obtain active particles. Then, the active particles are modified with a sub-modifier, so that the interior of the prepared alkali metal ion-doped copper iron manganese cathode material is active particles, and a polymer is connected to the surface of the active particles. The coating of the polymer can not only protect it, improve its cycle performance, but also improve the dispersibility of the active particles to avoid their agglomeration, enhance its performance, and the polymer also has good electrical conductivity, which can further improve the electrochemical performance of the alkali metal ion-doped copper iron manganese cathode material.

[0050] In the process of preparing the alkali metal ion-doped copper iron manganese cathode material, a particle modifier was first prepared. First, a nucleophilic substitution reaction occurred between the hydroxyl group on 8-hydroxy-2-methylquinoline and the bromine atom on bromoethane to obtain intermediate 1. Then, selenium dioxide was used to oxidize the methyl group on intermediate 1 to a hydroxyl group to obtain intermediate 2. Then, intermediate 2 and pyrrole reacted to form intermediate 3. Then, intermediate 3 and 4-bromo-2-thiophenecarboxaldehyde reacted to form intermediate 4 containing a porphyrin structure. Then, intermediate 4 and cobalt acetate reacted to form a porphyrin metal particle complex to obtain intermediate 5. Then, intermediate 5 and pyrrole reacted to introduce a pyrrole ring to obtain intermediate 6. Then, the ether bond on intermediate 7 was broken to form a hydroxyl group to obtain intermediate 7. Then, the hydroxyl group on intermediate 7 reacted with the epoxy group on γ-glycidoxypropyltrimethoxysilane to obtain the particle modifier; the molecular structure of the particle modifier contains a large number of siloxanes, which can be connected to the surface of the active particles after hydrolysis to form silanols, enhancing their dispersibility. At the same time, a large number of thiophene rings and pyrrole rings are introduced. Thiophene rings and pyrrole rings have good electrical conductivity, and the co-doped cobalt ions can provide a part of free electrons, thereby generating holes or electrons, which can further improve their electrical conductivity and also improve the conductivity, and then enhance the electrochemical performance of the active particles. Moreover, the pyrrole ring can form a polymer with pyrrole to wrap the active particles, not only protecting them and enhancing their cycle stability, but also enhancing the electrical conductivity of the formed polymer to further improve their electrochemical performance. Detailed implementation mode

[0051] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0052] Example 1:

[0053] This example is a preparation method of a particle modifier, including the following steps:

[0054] Step s1: Add 0.1 mol of 8-hydroxy-2-methylquinoline, 120 mL of dioxane, 0.1 mol of bromoethane, and 0.15 mol of anhydrous potassium carbonate into a three-necked flask equipped with a stirrer and a thermometer, stir and react at a temperature of 60 °C and a stirring rate of 400 r / min for 20 h. After the reaction is completed, cool the reaction product to room temperature, then extract it 2 times with dichloromethane, then wash the extraction solution 3 times with distilled water, then dry it with anhydrous magnesium sulfate, then filter it under vacuum, and rotate the filtrate to evaporate the solvent to obtain intermediate 1;

[0055] Step s2: Add 0.1 mol of selenium dioxide and 120 mL of dioxane into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a constant pressure dropping funnel. Stir and react for 30 min at a temperature of 25 °C and a stirring rate of 400 r / min. Then, while stirring, gradually add dropwise 50 mL of Intermediate 1 solution formed by dissolving 0.08 mol of Intermediate 1 in dioxane, control the dropping rate at 1 drop / s. After the dropping is completed, raise the temperature to reflux and continue to stir and react for 10 h. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration, rotary evaporate the filtrate to remove the solvent, and then recrystallize with dichloromethane to obtain Intermediate 2;

[0056] Step s3: Add 15 mL of Intermediate 2 and 10 mmol of pyrrole into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a constant pressure dropping funnel. Introduce nitrogen for protection. While stirring, gradually add dropwise 1 mmol of trifluoroacetic acid at a temperature of 20 °C and a stirring rate of 400 r / min, control the dropping rate at 1 drop / s. After the dropping is completed, continue to stir and react for 30 min. After the reaction is completed, adjust the reaction product to pH 7 with a 15% sodium hydroxide solution by mass fraction, then extract with dichloromethane twice, then wash the extract with distilled water three times, then dry with anhydrous magnesium sulfate, then perform vacuum filtration, rotary evaporate the filtrate to remove the solvent, and then recrystallize with anhydrous methanol to obtain Intermediate 3;

[0057] Step s4: Add 15 mmol of Intermediate 3, 10 mmol of 4-bromo-2-thiophenecarboxaldehyde and 120 mL of dichloromethane into a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel. While stirring, gradually add dropwise 5 mmol of trifluoroacetic acid at a temperature of 25 °C and a stirring rate of 400 r / min, control the dropping rate at 1 drop / s. After the dropping is completed, continue to stir and react for 30 min, then add 5 mmol of tetrachlorobenzoquinone and continue to stir and react for 8 h. After the reaction is completed, perform vacuum filtration on the reaction product, then rotary evaporate the filtrate to remove the solvent to obtain Intermediate 4;

[0058] Step s5: Add 10 mmol of Intermediate 4, 10 mmol of cobalt acetate and 80 mL of N,N-dimethylformamide into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser. Introduce nitrogen for protection. Stir and react for 20 min at a temperature of 25 °C and a stirring rate of 400 r / min, then raise the temperature to reflux and continue to stir and react for 5 h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, and then perform silica gel column chromatography on the evaporation product using a mixed solution of chloroform and anhydrous methanol mixed in a volume ratio of 5:1 as the eluent to obtain Intermediate 5;

[0059] Step s6: Add 10 mmol of intermediate 5, 10 mmol of pyrrole, 80 mL of anhydrous ether, and 10 mmol of potassium tert-butoxide into a three-necked flask equipped with a stirrer, a thermometer, and a gas guide tube. Introduce nitrogen for protection. Stir and react for 7 h under the conditions of a temperature of 25 °C and a stirring rate of 400 r / min. After the reaction is completed, pour the reaction product into ice water, then extract it twice with dichloromethane, then wash the extract three times with distilled water, then dry it with anhydrous magnesium sulfate, then perform vacuum filtration, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 6;

[0060] Step s7: Add 10 mmol of intermediate 7, 50 mL of tetrahydrofuran, and 30 mL of concentrated hydrochloric acid with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. Stir and react for 20 min under the conditions of a temperature of 25 °C and a stirring rate of 400 r / min, then raise the temperature to reflux and continue to stir and react for 15 h. After the reaction is completed, cool the reaction product to room temperature, then let it stand for liquid separation, and rotary evaporate the organic phase to remove the solvent to obtain intermediate 7;

[0061] Step s8: Add 10 mmol of intermediate 7, 35 mmol of γ-glycidoxypropyltrimethoxysilane, and 80 mL of anhydrous ethanol into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 3 h under the conditions of a temperature of 70 °C and a stirring rate of 400 r / min. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent to obtain the particle modifier.

[0062] Example 2:

[0063] This example is a preparation method of a particle modifier, including the following steps:

[0064] Step s1: Add 0.1 mol of 8-hydroxy-2-methylquinoline, 150 mL of dioxane, 0.1 mol of bromoethane, and 0.2 mol of anhydrous potassium carbonate into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 25 h under the conditions of a temperature of 65 °C and a stirring rate of 600 r / min. After the reaction is completed, cool the reaction product to room temperature, then extract it three times with dichloromethane, then wash the extract five times with distilled water, then dry it with anhydrous magnesium sulfate, then perform vacuum filtration, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 1;

[0065] Step s2: Add 0.1 mol of selenium dioxide and 150 mL of dioxane into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a constant-pressure dropping funnel. Stir and react for 40 min under the conditions of a temperature of 30 °C and a stirring rate of 600 r / min. Then, while stirring, gradually add dropwise 60 mL of Intermediate 1 solution formed by dissolving 0.1 mol of Intermediate 1 in 50 mL of dioxane, control the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to reflux and continue stirring and reacting for 15 h. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Rotate and evaporate the filtrate to remove the solvent, and then perform recrystallization with dichloromethane to obtain Intermediate 2;

[0066] Step s3: Add 20 mL of Intermediate 2 and 10 mmol of pyrrole into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a constant-pressure dropping funnel. Introduce nitrogen for protection. While stirring, gradually add dropwise 1.5 mmol of trifluoroacetic acid under the conditions of a temperature of 25 °C and a stirring rate of 600 r / min, control the dropping rate at 2 drops / s. After the dropping is completed, continue stirring and reacting for 50 min. After the reaction is completed, adjust the reaction product to pH 8 with a 20% sodium hydroxide solution by mass fraction, then extract with dichloromethane 3 times, then wash the extract with distilled water 5 times, then dry with anhydrous magnesium sulfate, then perform vacuum filtration. Rotate and evaporate the filtrate to remove the solvent, and then perform recrystallization with anhydrous methanol to obtain Intermediate 3;

[0067] Step s4: Add 20 mmol of Intermediate 3, 10 mmol of 4-bromo-2-thiophenecarboxaldehyde and 150 mL of dichloromethane into a three-necked flask equipped with a stirrer, a thermometer and a constant-pressure dropping funnel. While stirring, gradually add dropwise 7 mmol of trifluoroacetic acid under the conditions of a temperature of 30 °C and a stirring rate of 600 r / min, control the dropping rate at 2 drops / s. After the dropping is completed, continue stirring and reacting for 50 min. Then add 7 mmol of tetrachlorobenzoquinone and continue stirring and reacting for 10 h. After the reaction is completed, perform vacuum filtration on the reaction product, then rotate and evaporate the filtrate to remove the solvent to obtain Intermediate 4;

[0068] Step s5: Add 10 mmol of Intermediate 4, 10 mmol of cobalt acetate and 100 mL of N,N-dimethylformamide into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser. Introduce nitrogen for protection. Stir and react for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 600 r / min. Then raise the temperature to reflux and continue stirring and reacting for 7 h. After the reaction is completed, cool the reaction product to room temperature, then rotate and evaporate to remove the solvent. Then perform silica gel column chromatography on the evaporation product using a mixed solution of chloroform and anhydrous methanol mixed in a volume ratio of 6:1 as the eluent to obtain Intermediate 5;

[0069] Step s6: Add 10 mmol of intermediate 5, 10 mmol of pyrrole, 100 mL of anhydrous ether, and 15 mmol of potassium tert-butoxide into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 9 h at a temperature of 30 °C and a stirring rate of 600 r / min. After the reaction is completed, pour the reaction product into ice water, then extract it 3 times with dichloromethane, then wash the extract 5 times with distilled water, then dry it with anhydrous magnesium sulfate, then perform vacuum filtration, and rotary evaporate the filtrate to remove the solvent to obtain intermediate 6;

[0070] Step s7: Add 10 mmol of intermediate 7, 60 mL of tetrahydrofuran, and 40 mL of concentrated hydrochloric acid with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser. Stir and react for 30 min at a temperature of 30 °C and a stirring rate of 600 r / min, then raise the temperature to reflux and continue to stir and react for 20 h. After the reaction is completed, cool the reaction product to room temperature, then let it stand for liquid separation, and rotary evaporate the organic phase to remove the solvent to obtain intermediate 7;

[0071] Step s8: Add 10 mmol of intermediate 7, 40 mmol of γ-glycidoxypropyltrimethoxysilane, and 100 mL of anhydrous ethanol into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 5 h at a temperature of 80 °C and a stirring rate of 600 r / min. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent to obtain the particle modifier.

[0072] Example 3:

[0073] This example is a preparation method of an alkali metal ion-doped copper iron manganese cathode material, which is characterized by including the following steps:

[0074] Step one: Prepare the particle modifier according to the method of Example 2 for standby;

[0075] Step two: Add 20 mmol of copper sulfate pentahydrate, 10 mmol of ferrous sulfate heptahydrate, 20 mmol of manganese sulfate monohydrate, 0.15 g of cetyltrimethylammonium bromide, and 100 mL of ethanol solution with a volume fraction of 50% into a three-necked flask equipped with a stirrer, a thermometer, and a constant pressure dropping funnel. Stir and react for 20 min at a temperature of 25 °C and a stirring rate of 400 r / min to obtain a mixed ion solution. Then, add 30 mL of sodium hydroxide solution with a mass fraction of 35% dropwise into the mixed ion solution at a dropping rate of 1 drop / s. After the dropping is completed, raise the temperature to 150 °C and continue to stir and react for 10 h. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration, wash the filter cake 3 times with distilled water, and after drying, obtain the precursor;

[0076] Step 3: Add the precursor into a tube furnace, introduce argon for protection, calcine at 450 °C for 4 h at a heating rate of 2 °C / min, then continue to heat up to 800 °C and calcine for 8 h, and then cool down with the furnace. After grinding, active particles are obtained.

[0077] Step 4: Add 10 g of active particles, 0.8 g of particle modifier, and 60 mL of ethanol solution with a volume fraction of 70% into a three-necked flask equipped with a stirrer, thermometer, gas pipe, and reflux condenser. Introduce nitrogen for protection, stir and react at 25 °C and a stirring rate of 400 r / min for 20 min, then heat up to reflux and continue to stir and react for 3 h. Then cool down to 25 °C and add 2.6 g of anhydrous ferric chloride and 2.5 mL of pyrrole, and then continue to stir and react for 20 h. After the reaction is completed, vacuum filter the reaction product, wash the filter cake twice with anhydrous methanol and distilled water respectively, and then place it in a vacuum drying oven and dry at 80 °C for 8 h to obtain the alkali metal ion-doped copper iron manganese cathode material.

[0078] Example 4:

[0079] This example is a preparation method of an alkali metal ion-doped copper iron manganese cathode material, which is characterized by including the following steps:

[0080] Step 1: Prepare the particle modifier according to the method of Example 2 and set it aside.

[0081] Step 2: Add 20 mmol of copper sulfate pentahydrate, 10 mmol of ferrous sulfate heptahydrate, 20 mmol of manganese sulfate monohydrate, 0.25 g of cetyltrimethylammonium bromide, and 120 mL of ethanol solution with a volume fraction of 50% into a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir and react at 30 °C and a stirring rate of 600 r / min for 30 min to obtain a mixed ion solution. Then add 50 mL of sodium hydroxide solution with a mass fraction of 40% dropwise into the mixed ion solution at a dropping rate of 2 drops / s. After the dropping is completed, heat up to 160 °C and continue to stir and react for 15 h. After the reaction is completed, cool the reaction product to room temperature, then vacuum filter, wash the filter cake 5 times with distilled water, and after drying, obtain the precursor.

[0082] Step 3: Add the precursor into a tube furnace, introduce argon for protection, calcine at 470 °C for 5 h at a heating rate of 3 °C / min, then continue to heat up to 820 °C and calcine for 10 h, and then cool down with the furnace. After grinding, active particles are obtained.

[0083] Step 4: Add 10 g of active particles, 3.6 g of particle modifier, and 80 mL of ethanol solution with a volume fraction of 80% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a reflux condenser. Introduce nitrogen for protection, stir and react for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 600 r / min. Then, raise the temperature to reflux and continue stirring and reacting for 5 h. After that, cool down to 30 °C and add 5.2 g of anhydrous ferric chloride and 5.5 mL of pyrrole, and then continue stirring and reacting for 30 h. After the reaction is completed, vacuum filter the reaction product, wash the filter cake with anhydrous methanol and distilled water three times in sequence, and then place it in a vacuum drying oven and dry it at 85 °C for 10 h to obtain the alkali metal ion-doped copper iron manganese cathode material.

[0084] Comparative Example 1:

[0085] The difference between Comparative Example 1 and Example 4 is that no particle modifier is added.

[0086] Comparative Example 2:

[0087] The difference between Comparative Example 2 and Example 4 is that pyrrole is added instead of the particle modifier.

[0088] Mix the alkali metal ion-doped copper iron manganese cathode materials, acetylene black, and polyvinylidene fluoride in Comparative Examples 1-2 and Examples 3-4 evenly according to a mass ratio of 8:1:1, and then add N-methyl-2-pyrrolidone and mix evenly to form a cathode slurry with a solid content of 46%. Then, use a scraper to evenly coat the cathode slurry on the aluminum foil, and form a cathode sheet after drying and cutting.

[0089] Using 1 mol / L NaClO4 / PC solution as the electrolyte, WhatMan DF / D as the separator, metallic sodium as the anode, and the cathode sheet as the cathode, assemble a CR2016 type button cell, and test the performance of the CR2016 type button cell. The test conditions are 25 °C, a voltage range of 2.5-4.3 V, and a rate of 0.1 C. The test results are shown in the following table:

[0090] Sample <![CDATA[Initial charge specific capacity, mAh·g -1 > <![CDATA[Initial discharge specific capacity, mAh·g -1 > Coulomb efficiency, % Example 3 201.4 187.70 93.2 Example 4 213.7 204.08 95.5 Comparative Example 1 183.5 141.66 77.2 Comparative Example 2 178.8 154.13 86.2

[0091] Referring to the data in the above table, according to the comparison of Examples 3-4 and Comparative Examples 1-2, it can be known that the modified alkali metal ion-doped copper iron manganese cathode material has good charge-discharge specific capacity and good Coulomb efficiency, indicating its good cycling performance. The unmodified alkali metal ion-doped copper iron manganese cathode material has a relatively high charge specific capacity, but its cycling performance is poor. After pyrrole polymerization modification, its cycling performance can be improved, but its charge specific capacity decreases.

[0092] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0093] The above content is only an illustration and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar ways to substitute, as long as they do not deviate from the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

Claims

1. A preparation method of an alkali metal ion-doped copper iron manganese cathode material, characterized in that, It includes the following steps: Step 1: Add copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide, and ethanol solution into a three-necked flask, stir and react to obtain a mixed ionic solution. Then, gradually add sodium hydroxide solution dropwise into the mixed ionic solution. After the addition is complete, continue to stir and react. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Wash and dry the filter cake to obtain a precursor. Step 2: Add the precursor into a tube furnace for calcination, and then cool it with the furnace. After grinding, active particles are obtained. Step 3: Add the active particles, particle modifier, and ethanol solution into a three-necked flask, stir and react. Then, add anhydrous ferric chloride and pyrrole and continue to stir and react. After the reaction is completed, perform vacuum filtration on the reaction product. Wash and dry the filter cake to obtain the alkali metal ion-doped copper iron manganese cathode material. The particle modifier is prepared by the following steps: Step s1: Add 8-hydroxy-2-methylquinoline, dioxane, bromoethane, and anhydrous potassium carbonate into a three-necked flask, stir and react. After the reaction is completed, cool the reaction product to room temperature, then perform extraction. Wash and dry the extract, then perform vacuum filtration. Rotate and evaporate the filtrate to obtain intermediate 1. Step s2: Add selenium dioxide and dioxane into a four-necked flask, stir and react. Then, gradually add the intermediate 1 solution dropwise while stirring. After the addition is complete, continue to stir and react. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration. Rotate and evaporate the filtrate, and then perform recrystallization to obtain intermediate 2. Step s3: Add intermediate 2 and pyrrole into a three-necked flask, gradually add trifluoroacetic acid dropwise while stirring. After the addition is complete, continue to stir and react. After the reaction is completed, adjust the pH of the reaction product, then perform extraction. Wash and dry the extract, then perform vacuum filtration. Rotate and evaporate the filtrate, and then perform recrystallization to obtain intermediate 3. Step s4: Add intermediate 3, 4-bromo-2-thiophenecarboxaldehyde, and dichloromethane into a three-necked flask, gradually add trifluoroacetic acid dropwise while stirring. Then, add tetrachlorobenzoquinone and continue to stir and react. After the reaction is completed, perform vacuum filtration on the reaction product. Then, rotate and evaporate the filtrate to obtain intermediate 4. Step s5: Add intermediate 4, cobalt acetate, and N,N-dimethylformamide into a three-necked flask, stir and react. After the reaction is completed, cool the reaction product to room temperature, then rotate and evaporate. Perform silica gel column chromatography on the evaporation product to obtain intermediate 5. Step s6: Add intermediate 5, pyrrole, anhydrous ether, and potassium tert-butoxide into a three-necked flask, stir and react. After the reaction is completed, pour the reaction product into ice water, then perform extraction. Wash and dry the extract, then perform vacuum filtration. Rotate and evaporate the filtrate to obtain intermediate 6. Step s7: Add intermediate 7, tetrahydrofuran, and concentrated hydrochloric acid into a three-necked flask, stir and react. After the reaction is completed, cool the reaction product to room temperature, then let it stand for liquid separation. Rotate and evaporate the organic phase to obtain intermediate 7. Step s8: Add intermediate 7, γ-glycidyl ether oxypropyltrimethoxysilane, and absolute ethanol into a three-necked flask, stir and react. After the reaction is completed, cool the reaction product to room temperature, and then perform rotary evaporation to obtain a particle modifier.

2. The preparation method of an alkali metal ion-doped copper iron manganese cathode material according to claim 1, characterized in that, In step one, the dosage ratio of copper sulfate pentahydrate, ferrous sulfate heptahydrate, manganese sulfate monohydrate, cetyltrimethylammonium bromide, ethanol solution, and sodium hydroxide solution is 20 mmol: 10 mmol: 20 mmol: 0.15 - 0.25 g: 100 - 120 mL: 30 - 50 mL. The volume fraction of the ethanol solution is 50%, and the mass fraction of the sodium hydroxide solution is 35 - 40%.

3. The preparation method of an alkali metal ion-doped copper iron manganese cathode material according to claim 1, wherein In step two, the dosage ratio of the active particles, particle modifier, ethanol solution, anhydrous ferric chloride, and pyrrole is 10 g: 0.8 - 3.6 g: 60 - 80 mL: 2.6 - 5.2 g: 2.5 - 5.5 mL. The volume fraction of the ethanol solution is 70 - 80%.

4. The preparation method of an alkali metal ion-doped copper-iron-manganese cathode material according to claim 1, characterized in that, In step s1, the dosage ratio of 8-hydroxy-2-methylquinoline, dioxane, bromoethane, and anhydrous potassium carbonate is 0.1 mol: 120 - 150 mL: 0.1 mol: 0.15 - 0.2 mol; in step s2, the dosage ratio of selenium dioxide, dioxane, and intermediate 1 solution is 0.1 mol: 120 - 150 mL: 50 - 60 mL. The intermediate 1 solution is a solution formed by dissolving intermediate 1 in dioxane at a ratio of 0.08 - 0.1 mol: 50 mL.

5. The preparation method of an alkali metal ion-doped copper iron manganese cathode material according to claim 1, characterized in that, In step s3, the dosage ratio of intermediate 2, pyrrole, and trifluoroacetic acid is 15 - 20 mL: 10 mmol: 1 - 1.5 mmol; in step s4, the dosage ratio of intermediate 3, 4-bromo-2-thiophenecarboxaldehyde, trifluoroacetic acid, and tetrachlorobenzoquinone is 15 - 20 mmol: 10 mmol: 120 - 150 mL: 5 - 7 mmol: 5 - 7 mmol.

6. The preparation method of an alkali metal ion-doped copper iron manganese cathode material according to claim 1, wherein In step s5, the dosage ratio of intermediate 4, cobalt acetate, and N, N-dimethylformamide is 10 mmol: 10 mmol: 80 - 100 mL; in step s6, the dosage ratio of intermediate 5, pyrrole, anhydrous diethyl ether, and potassium tert-butoxide is 10 mmol: 10 mmol: 80 - 100 mL: 10 - 15 mmol.

7. The preparation method of an alkali metal ion-doped copper iron manganese cathode material according to claim 1, characterized in that, In step s7, the dosage ratio of intermediate 7, tetrahydrofuran, and concentrated hydrochloric acid is 10 mmol: 50 - 60 mL: 30 - 40 mL. The mass fraction of the concentrated hydrochloric acid is 37%; in step s8, the dosage ratio of intermediate 7, γ-glycidyl ether oxypropyltrimethoxysilane, and absolute ethanol is 10 mmol: 35 - 40 mmol: 80 - 100 mL.

8. An alkali metal ion-doped copper iron manganese cathode material, characterized in that, The alkali metal ion-doped copper iron manganese cathode material is prepared according to the preparation method of the alkali metal ion-doped copper iron manganese cathode material described in any one of claims 1 - 7.

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