Lithium battery positive electrode material applied to unmanned aerial vehicle and preparation method of lithium battery positive electrode material

Abstract

The invention discloses a lithium battery positive electrode material applied to an unmanned aerial vehicle and a preparation method of the lithium battery positive electrode material, and belongs to the technical field of lithium batteries. Through the design of two coating layers, the inner layer is a carbon layer with a relatively large pore diameter and relatively soft texture, the outer layer is a titanium dioxide layer, multifunctional modifier powder is impregnated into pores of the inner layer and is bonded with hydroxyl on the surface of the outer layer, and the coating layer is formed; the powder structure of the multifunctional modifier contains pyridine groups and methoxyl groups, the whole multifunctional modifier shows relatively strong alkalinity, can neutralize hydrogen sulfate ions in a battery, and can be conjugated with adjacent pyridine rings to improve the capability of neutralizing the hydrogen sulfate ions, oxygen atoms on methoxyl anions carry certain negative charges, and thus the hydrogen sulfate ions can be neutralized. According to the present invention, the porous carbon material has characteristics of strong adsorption, strong attraction with the positively charged sodium ions, and sodium ion adsorption, and the multifunctional modifier powder is tightly filled in the porous carbon material through impregnation and grafting so as to achieve the good neutralization effect on the hydrogen sulfate radical ions and the sodium ions remaining in the pores.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and particularly relates to a cathode material for a lithium battery applied to an unmanned aerial vehicle and a preparation method thereof. Background Art

[0002] A lithium battery is a device that directly converts the chemical energy of its own electrode material into electrical energy. Its negative electrode is lithium metal or lithium alloy with extremely high energy density. Lithium batteries have advantages such as high energy density, low self-discharge, and high specific energy compared to secondary batteries, and are widely used in daily life. With the booming development of the unmanned aerial vehicle industry, the power demand for unmanned aerial vehicles has gradually increased. In current research, there is a tendency to convert fuel-powered unmanned aerial vehicles into electric unmanned aerial vehicles to reduce the flight noise and failure rate of unmanned aerial vehicles, enabling unmanned aerial vehicles to have the ability to start and stop at any time, glide silently, and cruise quietly during mission execution, greatly improving the mission performance of unmanned aerial vehicles. Unmanned aerial vehicle batteries have relatively high requirements for battery power. When quickly increasing the throttle from a hovering state to the maximum speed, the battery power will increase rapidly, with a several-fold increase in power within a short period of time. Therefore, it is necessary to solve the problems of high capacity, high rate, and cycle stability of unmanned aerial vehicle batteries.

[0003] Chinese Patent Publication No. CN112968175B discloses a modification method of a lithium battery cathode active material, a modified lithium battery cathode active material, a cathode, and a lithium battery. By treating MnO2 with an LiOH solution, alkaline lithium hydroxide easily reacts with acidic hydrogen sulfate ions. However, sodium ions in the pores of MnO2 may be partially encapsulated or tightly bound to the structure, resulting in incomplete replacement of sodium ions by lithium ions and incomplete neutralization reaction: the distribution of hydrogen sulfate ions in the pores may be uneven, and alkaline LiOH is difficult to completely penetrate and react with them, resulting in the continued presence of residual acidic ions. When the battery works for a long time, hydrogen sulfate ions and sodium ions are gradually released, thus affecting the service life of the battery. Summary of the Invention

[0004] The purpose of the present invention is to provide a cathode material for a lithium battery applied to an unmanned aerial vehicle and a preparation method thereof. Through the design of two coating layers, the inner layer is a carbon layer with larger pore size and softer texture, and the outer layer is a titanium dioxide layer. A multifunctional modifier powder is impregnated into the pores of the inner layer and bonded to the hydroxyl groups on the outer surface. The multifunctional modifier powder structure contains pyridine groups and methoxy groups, and overall shows strong alkalinity, which can neutralize hydrogen sulfate ions in the battery and can conjugate with adjacent pyridine rings to improve the ability to neutralize hydrogen sulfate ions. The oxygen atom on the methoxy anion carries a certain negative charge and can form a strong attraction with positively charged sodium ions, which is beneficial to the adsorption of sodium ions. The multifunctional modifier powder is tightly filled inside through impregnation and grafting, so as to have a good neutralization effect on hydrogen sulfate ions and sodium ions remaining inside the pores.

[0005] Further optimize the ion distribution of the battery.

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] A cathode material for lithium batteries applied to unmanned aerial vehicles is prepared by the following steps:

[0008] Step 1: The modifier precursor solution undergoes an alkylation reaction under alkaline conditions to obtain a methoxy-modified modifier powder. Add isonicotinyl chloride hydrochloride, triethylamine, and dichloromethane into the reaction kettle, stir at 20 - 25 °C and 400 - 500 r / min for 30 - 40 min, then add the methoxy-modified modifier powder, continue to stir and react for 18 - 24 h, concentrate, wash the concentrated solution with deionized water 2 - 3 times, then transfer it to ethyl acetate for recrystallization, and crush the obtained solid to obtain a multifunctional modifier powder with a particle size of 10 - 20 μm.

[0009] Step 2: The porous matrix powder obtained after coating and carbonization is acidified to obtain an activated porous matrix powder; add the activated porous matrix powder, multifunctional modifier powder, and deionized water into the reaction kettle, perform vacuum impregnation at 50 - 65 °C and 400 - 500 r / min for 2 - 3 h, filter, wash the filter cake with deionized water and absolute ethanol 2 - 3 times respectively, and perform vacuum drying to obtain a modified activated porous matrix powder;

[0010] Step 3: Add the modified activated porous matrix powder, titanium tetrachloride, and deionized water into the reaction kettle, stir in an oxygen atmosphere at 40 - 50 °C and 500 - 600 r / min for 1 - 2 h, filter, wash the filter cake with deionized water and absolute ethanol 2 - 3 times respectively, and perform vacuum drying to obtain a cathode material for lithium batteries applied to unmanned aerial vehicles.

[0011] Further, in Step 1, the dosage ratio of isonicotinyl chloride hydrochloride, triethylamine, dichloromethane, and methoxy-modified modifier powder is 25 - 28 g : 4 - 5 mL : 300 - 400 mL : 20 - 30 g.

[0012] Further, in Step 2, the dosage ratio of activated porous matrix powder, multifunctional modifier powder, and deionized water is 12 - 18 g : 20 - 30 g : 300 - 400 mL.

[0013] Further, in Step 3, the dosage ratio of modified activated porous matrix powder, titanium tetrachloride, and deionized water is 15 - 20 g : 40 - 50 mL : 400 - 500 mL.

[0014] Further, the specific steps of the methoxy-modified modifier powder in Step 1 are as follows:

[0015] Add the modifier precursor solution and N,N-dimethylformamide into the reaction kettle, stir for 5 - 10 min under the conditions of 20 - 25 °C and 500 - 600 r / min, then under the protection of nitrogen, add the catalyst cuprous bromide, heat to 60 - 70 °C and continue to stir for 30 - 40 min, then add the sodium hydroxide solution with a mass fraction of 40 - 50% and methanol, heat to 85 - 90 °C and continue to stir for 5 - 6 h, filter, wash the filter cake with deionized water and absolute ethanol for 2 - 3 times respectively, and dry it under vacuum to obtain the methoxy-modified modifier powder.

[0016] Furthermore, the dosage ratio of the modifier precursor solution, N,N-dimethylformamide, cuprous bromide, sodium hydroxide solution and methanol is 40 - 50 mL : 80 - 100 mL : 1 - 2 g : 15 - 20 mL : 50 - 60 mL.

[0017] Furthermore, the specific steps of the modifier precursor solution in step one are as follows:

[0018] Add 2,5-dihydroxybenzoic acid, N,N'-bis(2-hydroxyethyl)ethylenediamine, bromoacetic acid and deionized water into the reaction kettle, stir for 1 - 2 h under the conditions of nitrogen atmosphere, 20 - 25 °C and 500 - 600 r / min, adjust the pH value to 10 - 11 with the potassium hydroxide solution with a mass fraction of 50 - 60%, raise the temperature to 40 - 45 °C and continue to stir for 48 - 60 h, add hydrochloric acid to adjust the pH value of the solution to 5 - 6, extract the product with the potassium chloride solution with a mass fraction of 40 - 50% and ethyl acetate for 2 - 3 times, and combine the organic phases to obtain the modifier precursor solution.

[0019] Furthermore, the dosage ratio of 2,5-dihydroxybenzoic acid, N,N'-bis(2-hydroxyethyl)ethylenediamine, bromoacetic acid and deionized water is 20 - 30 g : 30 - 40 g : 10 - 12 mL : 400 - 500 mL.

[0020] Furthermore, the specific steps of activating the porous matrix powder in step two are as follows:

[0021] Add the porous matrix powder, the hydrochloric acid solution with a mass fraction of 5 - 8% and the hydrogen peroxide solution with a mass fraction of 7 - 8% into the reaction kettle, stir for 1 - 2 h under the conditions of 70 - 80 °C and 500 - 600 r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it under vacuum at 60 - 80 °C for 1 - 2 h to obtain the activated porous matrix powder.

[0022] Furthermore, the dosage ratio of the porous matrix powder, hydrochloric acid solution and hydrogen peroxide solution is 30 - 40 g : 150 - 180 mL : 50 - 60 mL.

[0023] Furthermore, the specific steps of the porous matrix powder in step two are as follows:

[0024] Styrene, divinylbenzene and deionized water are added into a reaction kettle, and stirred for 20 - 30 min under the conditions of 20 - 25 °C and 500 - 600 r / min. Manganese dioxide powder with a particle size of 5 - 10 μm, urea, benzoyl peroxide as an initiator and sodium dodecylbenzenesulfonate as a dispersant are added into the reaction kettle, and the reaction is continued with stirring for 1 - 2 h. Then, filtration is carried out, and the filter cake is washed 2 - 3 times with deionized water and absolute ethanol respectively, freeze-dried, transferred to a muffle furnace, and kept warm at 800 - 900 °C for 4 - 6 h under nitrogen protection, and then naturally cooled to obtain porous matrix powder.

[0025] Furthermore, the dosage ratio of styrene, divinylbenzene, deionized water, manganese dioxide powder, urea, benzoyl peroxide and sodium dodecylbenzenesulfonate is 40 - 50 mL : 30 - 40 mL : 500 - 600 mL : 70 - 80 g : 1 - 2 g : 4 - 5 g : 2 - 4 g.

[0026] Advantages of the present invention:

[0027] 1. The lithium battery cathode material of the unmanned aerial vehicle prepared by the present invention can effectively inhibit the side reaction between the active substance of the lithium ion battery cathode material and the electrolyte, effectively avoid the influence of hydrogen sulfate ions and sodium ions, has good cycle performance, small volume change and long service life.

[0028] 2. The lithium battery cathode material of the present invention, through the design of two coating layers, the inner layer is a carbon layer with larger pore size and softer texture, which reduces the contact area with the electrolyte, reduces the decomposition of the electrolyte, thereby improving the cycle stability and safety of the battery, and can absorb the stress generated by volume change during the charge and discharge process of the battery, reducing the mechanical damage of the material. The titanium dioxide layer deposited on the outer surface has excellent chemical stability, which can protect the internal electrode material from chemical corrosion and oxidation, thereby prolonging the service life of the battery.

[0029] 4. The multifunctional modifier powder enters the pores of the double carbon layer by impregnation and bonds with the hydroxyl groups on the outer surface, improving the stability of the multifunctional modifier powder in the pores. The structure of the multifunctional modifier powder contains pyridine groups and methoxy groups. The presence of multiple pyridine groups makes the modifier as a whole show strong alkalinity, which can neutralize and remove hydrogen sulfate ions in the battery, thereby reducing the negative impact of these impurity ions on the battery performance; the oxygen atom on the methoxy group has a lone pair of electrons, which can conjugate with the adjacent pyridine ring. This conjugation effect causes the redistribution of the pyridine ring, usually resulting in an increase in the electron cloud density of the nitrogen atom on the ring, and its ability to accept protons also increases accordingly. The oxygen atom on the methoxy anion has a certain negative charge, which can form a strong attraction with the positively charged sodium ion, thereby facilitating the adsorption and binding of sodium ions and further optimizing the ion distribution of the battery. Detailed implementation manners

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with 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. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Embodiment 1: A cathode material for lithium batteries applied to drones is prepared through the following steps:

[0032] S1: Add 40 mL of styrene, 30 mL of divinylbenzene, and 500 mL of deionized water into a reaction kettle, stir at 20°C and 500 r / min for 20 min, add 70 g of manganese dioxide powder with a particle size of 5 - 10 μm, 1 g of urea as a pore-forming agent, 4 g of benzoyl peroxide as an initiator, and 2 g of sodium dodecylbenzenesulfonate as a dispersant into the reaction kettle, continue to stir and react for 1 h, centrifuge, collect the manganese dioxide wrapped with polystyrene, wash it twice with deionized water and absolute ethanol respectively, freeze-dry, transfer it to a muffle furnace, keep it warm at 800°C under nitrogen protection for 4 h, and cool it naturally to obtain porous matrix powder.

[0033] Under the action of the pore-forming agent, monomers such as styrene polymerize with manganese dioxide powder particles as templates and wrap around the surface of manganese dioxide particles to form polystyrene macroporous resin. After carbonization, a first layer of carbon layer with large pore size and soft texture is formed on the surface of manganese dioxide particles.

[0034] S2: Add 20 - 30 g of 2,5-dihydroxybenzoic acid, 30 - 40 g of N,N'-bis(2-hydroxyethyl)ethylenediamine, 10 - 12 mL of bromoacetic acid, and 400 - 500 mL of deionized water into a reaction kettle, stir at 20 - 25°C and 500 - 600 r / min for 1 - 2 h under a nitrogen atmosphere, adjust the pH value to 10 - 11 with a potassium hydroxide solution with a mass fraction of 50 - 60%, raise the temperature to 40 - 45°C and continue to stir for 48 - 60 h, add hydrochloric acid to adjust the pH value of the solution to 5 - 6, extract the product 2 - 3 times with a potassium chloride solution with a mass fraction of 40 - 50% and ethyl acetate, combine the organic phases to obtain a modifier precursor solution.

[0035] S3: Add 40 - 50 mL of modifier precursor solution and 80 - 100 mL of N,N - dimethylformamide into the reaction kettle, stir for 5 - 10 min under the conditions of 20 - 25 °C and 500 - 600 r / min, then under nitrogen protection, add 1 - 2 g of catalyst cuprous bromide, heat to 60 - 70 °C and continue to stir for 30 - 40 min, then add 15 - 20 mL of sodium hydroxide solution with a mass fraction of 40 - 50% and 50 - 60 mL of methanol, heat to 85 - 90 °C and continue to stir for 5 - 6 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, dry in vacuum at 60 °C for 1 h to obtain methoxy - modified modifier powder; Add 25 - 28 g of isonicotinyl chloride hydrochloride, 4 - 5 mL of triethylamine and 300 - 400 mL of dichloromethane into the reaction kettle, stir for 30 - 40 min under the conditions of 20 - 25 °C and 400 - 500 r / min, then add 20 - 30 g of methoxy - modified modifier powder, continue to stir and react for 18 - 24 h, concentrate, wash the concentrated solution with deionized water for 2 - 3 times, then transfer it to ethyl acetate for recrystallization, crush the obtained solid to obtain multifunctional modifier powder with a particle size of 10 - 20 μm.

[0036] Due to the relatively large electronegativity of the nitrogen atom and the uneven distribution of the electron cloud density of the pyridine ring, the lone pair of electrons on the nitrogen atom can partially participate in the conjugated system of the ring. This conjugation effect makes the nitrogen atom on the pyridine ring show a certain basicity and be able to accept protons to form positively charged ions. Therefore, in the multifunctional modifier powder, the presence of multiple pyridine groups makes the compound as a whole show strong basicity and can neutralize the bisulfate ions in the lithium - ion battery.

[0037] Methoxy is a typical electron - donating group, and the lone pair of electrons on its oxygen atom can conjugate with the adjacent pyridine ring. This conjugation effect redistributes the electron cloud density on the pyridine ring, resulting in an increase in the electron cloud density of the nitrogen atom on the ring. Due to the increase in the electron cloud density on the nitrogen atom, its ability to accept protons also increases.

[0038] And the oxygen atom on the methoxy anion carries a certain negative charge, while the sodium ion carries a certain positive charge. Due to the gravitational interaction between opposite charges, the gravitational interaction between the sodium ion and the methoxy anion is relatively strong and can more easily form a complex. This gravitational interaction makes methoxy have a certain affinity in an environment where sodium ions exist, which is beneficial to the adsorption and binding of sodium ions.

[0039] S4: Add 30 - 40 g of porous matrix powder, 150 - 180 mL of hydrochloric acid solution with a mass fraction of 5 - 8%, and 50 - 60 mL of hydrogen peroxide solution with a mass fraction of 7 - 8% into the reaction kettle. Stir for 1 - 2 h under the conditions of 70 - 80 °C and 500 - 600 r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 60 - 80 °C for 1 - 2 h to obtain activated porous matrix powder; Add 12 - 18 g of activated porous matrix powder, 20 - 30 g of multifunctional modifier powder, and 300 - 400 mL of deionized water into the reaction kettle. Vacuum impregnate for 2 - 3 h under the conditions of 50 - 65 °C and 400 - 500 r / min, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, and vacuum dry at 60 °C for 1 h to obtain modified activated porous matrix powder;

[0040] Add 15 - 20 g of modified activated porous matrix powder, 40 - 50 mL of titanium tetrachloride, and 400 - 500 mL of deionized water into the reaction kettle. Stir for 1 - 2 h under the conditions of 40 - 50 °C and 500 - 600 r / min in an oxygen atmosphere, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2 - 3 times, and vacuum dry to obtain the positive electrode material of the lithium battery applied to the drone.

[0041] The titanium dioxide layer deposited on the outer surface has excellent chemical stability, which can protect the internal electrode material from chemical corrosion and oxidation, helping to improve the durability and service life of the electrode material. Carbon fiber can enhance high strength and rigidity.

[0042] Example 2: A positive electrode material of a lithium battery applied to a drone is prepared by the following steps:

[0043] S1: Add 45 mL of styrene, 35 mL of divinylbenzene, and 550 mL of deionized water into the reaction kettle. Stir for 25 min under the conditions of 23 °C and 550 r / min. Add 75 g of manganese dioxide powder with a particle size of 5 - 10 μm, 1.2 g of urea as a pore-forming agent, 4.5 g of benzoyl peroxide as an initiator, and 2.5 g of sodium dodecylbenzenesulfonate as a dispersant into the reaction kettle, and continue to stir and react for 1.2 h. Centrifuge, collect the manganese dioxide wrapped by polystyrene, wash it with deionized water and absolute ethanol respectively for 2 times, freeze-dry, transfer it to a muffle furnace, and keep it warm at 850 °C for 5 h under nitrogen protection, and cool naturally to obtain porous matrix powder.

[0044] S2: Add 25 g of 2,5-dihydroxybenzoic acid, 35 g of N,N'-bis(2-hydroxyethyl)ethylenediamine, 11 mL of bromoacetic acid, and 450 mL of deionized water into a reaction kettle. Stir for 1.2 h under the conditions of nitrogen atmosphere, 23 °C, and 550 r / min. Adjust the pH value to 10 with a 55% potassium hydroxide solution by mass. Heat up to 43 °C and continue stirring for 50 h. Add hydrochloric acid to adjust the pH value of the solution to 5. Extract the product twice with a 40 - 50% potassium chloride solution by mass and ethyl acetate. Combine the organic phases to obtain a modifier precursor solution.

[0045] S3: Add 45 mL of the modifier precursor solution and 90 mL of N,N-dimethylformamide into a reaction kettle. Stir for 7 min under the conditions of 23 °C and 550 r / min. Then, under nitrogen protection, add 1.2 g of the catalyst cuprous bromide, heat up to 65 °C, and continue stirring for 35 min. Add 17 mL of a 45% sodium hydroxide solution by mass and 55 mL of methanol, heat up to 87 °C, and continue stirring for 5.6 h. Filter, wash the filter cake twice with deionized water and absolute ethanol respectively, and dry it under vacuum at 70 °C for 1.2 h to obtain a methoxy-modified modifier powder; Add 27 g of isonicotinyl chloride hydrochloride, 4.5 mL of triethylamine, and 350 mL of dichloromethane into a reaction kettle. Stir for 35 min under the conditions of 23 °C and 450 r / min. Then add 25 g of the methoxy-modified modifier powder and continue stirring for reaction for 20 h. Concentrate, wash the concentrated solution three times with deionized water, then transfer it to ethyl acetate for recrystallization. Crush the obtained solid to obtain a multifunctional modifier powder with a particle size of 10 - 20 μm.

[0046] S4: Add 40 g of porous matrix powder, 180 mL of an 8% hydrochloric acid solution by mass, and 60 mL of an 8% hydrogen peroxide solution by mass into a reaction kettle. Stir for 1.2 h under the conditions of 80 °C and 600 r / min. Filter, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it under vacuum at 80 °C for 1.2 h to obtain activated porous matrix powder; Add 16 g of the activated porous matrix powder, 25 g of the multifunctional modifier powder, and 350 mL of deionized water into a reaction kettle. Vacuum impregnate for 2.3 h under the conditions of 55 °C and 450 r / min. Filter, wash the filter cake 2 - 3 times with deionized water and absolute ethanol respectively, and dry it under vacuum at 70 °C for 1.2 h to obtain modified activated porous matrix powder; Add 18 g of the modified activated porous matrix powder, 45 mL of titanium tetrachloride, and 450 mL of deionized water into a reaction kettle. Stir for 1.2 h under the conditions of oxygen atmosphere, 43 °C, and 550 r / min. Filter, wash the filter cake twice with deionized water and absolute ethanol respectively, and dry it under vacuum to obtain a lithium battery cathode material for drones.

[0047] Example 3: A cathode material for lithium batteries applied to drones is prepared by the following steps:

[0048] S1: Add 50 mL of styrene, 40 mL of divinylbenzene, and 600 mL of deionized water into a reaction kettle, stir for 30 min under the conditions of 25 °C and 600 r / min, add 80 g of manganese dioxide powder with a particle size of 5 - 10 μm, 2 g of urea as a pore-forming agent, 5 g of benzoyl peroxide as an initiator, and 4 g of sodium dodecylbenzenesulfonate as a dispersant into the reaction kettle, continue to stir and react for 2 h, centrifuge, collect the manganese dioxide wrapped with polystyrene, wash it 3 times with deionized water and absolute ethanol respectively, freeze-dry, transfer it to a muffle furnace, keep it at 900 °C for 6 h under nitrogen protection, and cool it naturally to obtain porous matrix powder.

[0049] S2: Add 30 g of 2,5-dihydroxybenzoic acid, 40 g of N,N'-bis(2-hydroxyethyl)ethylenediamine, 12 mL of bromoacetic acid, and 500 mL of deionized water into a reaction kettle, stir for 2 h under the conditions of nitrogen atmosphere, 25 °C and 600 r / min, adjust the pH value to 11 with a 60% potassium hydroxide solution by mass fraction, raise the temperature to 45 °C and continue to stir for 60 h, add hydrochloric acid to adjust the pH value of the solution to 6, extract the product 3 times with a 50% potassium chloride solution by mass fraction and ethyl acetate, combine the organic phases to obtain a modifier precursor solution.

[0050] S3: Add 50 mL of the modifier precursor solution and 100 mL of N,N-dimethylformamide into a reaction kettle, stir for 10 min under the conditions of 25 °C and 600 r / min, then under nitrogen protection, add 2 g of copper(I) bromide as a catalyst, heat to 70 °C and continue to stir for 40 min, then add 20 mL of a 50% sodium hydroxide solution by mass fraction and 60 mL of methanol, heat to 90 °C and continue to stir for 5 - 6 h, filter, wash the filter cake 2 - 3 times with deionized water and absolute ethanol respectively, dry it in vacuum at 80 °C for 2 h to obtain methoxy-modified modifier powder; add 28 g of isonicotinyl chloride hydrochloride, 5 mL of triethylamine, and 400 mL of dichloromethane into a reaction kettle, stir for 40 min under the conditions of 20 - 25 °C and 400 - 500 r / min, then add 30 g of methoxy-modified modifier powder, continue to stir and react for 24 h, concentrate, wash the concentrated solution 3 times with deionized water, then transfer it to ethyl acetate for recrystallization, crush the obtained solid to obtain multifunctional modifier powder with a particle size of 20 μm.

[0051] S4: Add 40 g of porous matrix powder, 180 mL of hydrochloric acid solution with a mass fraction of 8%, and 60 mL of hydrogen peroxide solution with a mass fraction of 8% into a reaction kettle, stir for 2 h under the conditions of 80 °C and 600 r / min, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and vacuum dry at 80 °C for 2 h to obtain activated porous matrix powder; Add 18 g of activated porous matrix powder, 30 g of multifunctional modifier powder, and 400 mL of deionized water into a reaction kettle, vacuum impregnate for 3 h under the conditions of 65 °C and 500 r / min, filter, wash the filter cake with deionized water and absolute ethanol three times respectively, and vacuum dry at 80 °C for 2 h to obtain modified activated porous matrix powder; Add 20 g of modified activated porous matrix powder, 50 mL of titanium tetrachloride, and 500 mL of deionized water into a reaction kettle, stir for 2 h under the conditions of 50 °C and 600 r / min in an oxygen atmosphere, filter, wash the filter cake with deionized water and absolute ethanol three times respectively, and vacuum dry to obtain the positive electrode material of a lithium battery applied to an unmanned aerial vehicle.

[0052] Comparative Example 1: On the basis of Example S3, replace the porous matrix powder in step S4 with manganese dioxide powder with the same mass and a particle size of 5 - 10 μm in step S1, and keep the other steps unchanged to prepare the positive electrode material of a lithium battery applied to an unmanned aerial vehicle.

[0053] Comparative Example 2: On the basis of Example S3, replace the multifunctional modifier powder in step S4 with methoxy-modified modifier powder in step S3, and keep the other steps unchanged to prepare the positive electrode material of a lithium battery applied to an unmanned aerial vehicle.

[0054] Comparative Example 3: On the basis of Example S3, directly use the multi-modified activated porous matrix powder in step S6 as the positive electrode material of a lithium battery applied to an unmanned aerial vehicle.

[0055] In the examples and comparative examples:

[0056] N,N'-bis(2-hydroxyethyl)ethylenediamine was purchased from Sigma-Aldrich.

[0057] Manganese dioxide powder was purchased from Hunan Daji Environmental Protection and Energy Saving Materials Co., Ltd.

[0058] Isonicotinyl chloride hydrochloride was purchased from Shanghai Macklin Biochemical Co., Ltd.

[0059] The performance of the lithium battery cathode materials prepared in Examples 1 - 3 and Comparative Examples 1 - 3 for use in drones was tested, and the results are shown in Table 1: First, the active material, conductive agent (Ketjenblack), and binder (polyvinylidene fluoride) were weighed according to a mass ratio of 7:2:1 and mixed and ground evenly. Then, an appropriate amount of N-methylpyrrolidone (NMP) was added to the slurry while grinding. When the slurry was ground to be viscous and without obvious granularity, the slurry was transferred to the matte side of the copper foil and evenly coated using a film doctor. Subsequently, the copper foil was immediately placed in a vacuum oven to dry to remove the NMP and trace moisture in the slurry. The CR2032 coin cells were assembled in a glove box under an argon atmosphere, where the contents of water and oxygen in the glove box were strictly controlled below 0.01 ppm. The coin cells were assembled in the order of the positive electrode case, electrode sheet, separator, lithium / sodium metal sheet, gasket, spring piece, and negative electrode case. During this process, an appropriate amount of electrolyte needed to be dropped. Finally, the battery was compacted using a hydraulic sealer. The sodium sheet was prepared by rolling small pieces of metallic sodium until flat and then cutting them into square thin sheets of approximately 1.0 mm × 1.0 mm. The separator models used in the lithium-ion battery and sodium-ion battery were Celgard 2400 and Whatman GF / D, respectively. The electrolytes used were an ether-based electrolyte (ethylene glycol dimethyl ether (DME) with 1.0 M NaPF6) and an ester-based electrolyte (EC:DEC (1:1) with 5.0% FEC and 1.0 M NaClO4) sold by Duoduo Chemical Reagent Network.

[0060] Table 1 Performance Test Table of Lithium Battery Cathode Materials for Use in Drones

[0061]

[0062]

[0063] As can be seen from Table 1, the conductivity, capacity retention rate, first efficiency, and first discharge capacity of the lithium battery cathode materials prepared in Examples 1 - 3 for use in drones are significantly superior to those of the comparative examples, and the percentage change in volume is significantly lower than that of the comparative examples, indicating that the lithium battery cathode materials prepared by the present invention for use in drones can effectively inhibit the side reactions between the active substances of the lithium-ion battery cathode material and the electrolyte, have good cycle performance, small volume change, and long service life.

[0064] In Comparative Example 1, the porous matrix powder was replaced with manganese dioxide powder, losing the carbon layer with a softer texture and larger pores inside, and being unable to better relieve the stress caused by volume change. Through the synergistic effect of the carbon layer and the titanium dioxide layer, the contact with the electrolyte can be better isolated, thereby improving the cycle stability and safety of the battery. The inner carbon layer will also increase the conductivity.

[0065] In Comparative Example 2, the multi-functional modifier powder was replaced with a methoxy-modified modifier powder. Only the methoxy-modified modifier powder, whose structural formula does not contain a pyridine group, cannot better neutralize the bisulfate ions in the electrode material, thereby affecting the performance of the battery material.

[0066] In Comparative Example 3, the multi-modified activated porous matrix powder was directly used as the cathode material of a lithium battery applied to an unmanned aerial vehicle. The titanium dioxide layer deposited on the outer surface has excellent chemical stability, which can protect the internal electrode material from chemical corrosion and oxidation, thereby extending the service life of the battery.

[0067] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0068] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a cathode material for a lithium battery applied to a drone, characterized in that, It includes the following steps: Step 1: Add isonicotinyl chloride hydrochloride, triethylamine and dichloromethane into a reaction kettle, stir at 20 - 25°C and 400 - 500 r / min for 30 - 40 min, add methoxy-modified modifier powder and continue stirring for 18 - 24 h, concentrate, wash the concentrated solution with deionized water 2 - 3 times, then transfer it to ethyl acetate for recrystallization, crush the obtained solid to obtain multifunctional modifier powder with a particle size of 10 - 20 μm; Step 2: Obtain activated porous matrix powder by acidifying the porous matrix powder; Add the activated porous matrix powder, multifunctional modifier powder and deionized water into the reaction kettle according to the dosage ratio of 12 - 18 g : 20 - 30 g : 300 - 400 mL, carry out vacuum impregnation at 50 - 65°C and 400 - 500 r / min for 2 - 3 h, filter, wash the filter cake with deionized water and absolute ethanol respectively 2 - 3 times, and carry out vacuum drying to obtain modified activated porous matrix powder; Step 3: Add the modified activated porous matrix powder, titanium tetrachloride and deionized water into the reaction kettle according to the dosage ratio of 15 - 20 g : 40 - 50 mL : 400 - 500 mL, under an oxygen atmosphere, stir at 40 - 50°C and 500 - 600 r / min for 1 - 2 h, filter, wash the filter cake with deionized water and absolute ethanol respectively 2 - 3 times, and carry out vacuum drying to obtain the cathode material of a lithium battery applied to an unmanned aerial vehicle; The dosage ratio of the isonicotinyl chloride hydrochloride, triethylamine, dichloromethane and methoxy-modified modifier powder is 25 - 28 g : 4 - 5 mL : 300 - 400 mL : 20 - 30 g.

2. The preparation method of a lithium battery cathode material applied to a drone according to claim 1, characterized in that, The methoxy-modified modifier powder in Step 1 is prepared by the following steps: Add the modifier precursor solution and N,N-dimethylformamide into the reaction kettle, stir at 20 - 25°C and 500 - 600 r / min for 5 - 10 min, under nitrogen protection, add cuprous bromide, heat to 60 - 70°C and continue stirring for 30 - 40 min, then add 40 - 50 wt% sodium hydroxide solution and methanol, heat to 85 - 90°C and continue stirring for 5 - 6 h, filter, wash the filter cake with deionized water and absolute ethanol respectively 2 - 3 times, and carry out vacuum drying to obtain methoxy-modified modifier powder.

3. The preparation method of a lithium battery cathode material applied to a drone according to claim 2, characterized in that, The dosage ratio of the modifier precursor solution, N,N-dimethylformamide, cuprous bromide, sodium hydroxide solution and methanol is 40 - 50 mL : 80 - 100 mL : 1 - 2 g : 15 - 20 mL : 50 - 60 mL.

4. The preparation method of a lithium battery cathode material applied to an unmanned aerial vehicle according to claim 2, characterized in that, The modifier precursor solution is prepared by the following steps: Add 2,5-dihydroxybenzoic acid, N,N'-bis(2-hydroxyethyl)ethylenediamine, bromoacetic acid and deionized water into the reaction kettle, under a nitrogen atmosphere, stir at 20 - 25°C and 500 - 600 r / min for 1 - 2 h, adjust the pH value to 10 - 11 with potassium hydroxide solution, continue stirring at 40 - 45°C for 48 - 60 h, adjust the pH value to 5 - 6 with hydrochloric acid, extract the product with 40 - 50 wt% potassium chloride solution and ethyl acetate 2 - 3 times, and combine the organic phases to obtain the modifier precursor solution.

5. The preparation method of a lithium battery cathode material applied to an unmanned aerial vehicle according to claim 4, characterized in that, The dosage ratio of the 2,5-dihydroxybenzoic acid, N,N'-bis(2-hydroxyethyl)ethylenediamine, bromoacetic acid and deionized water is 20-30 g: 30-40 g: 10-12 mL: 400-500 mL.

6. The preparation method of a lithium battery cathode material applied to an unmanned aerial vehicle according to claim 1, characterized in that, The specific steps for acidifying the porous matrix powder described in Step 2 are as follows: Add the porous matrix powder, 5-8 wt% hydrochloric acid solution and 7-8 wt% hydrogen peroxide solution into a reaction kettle, stir at 70-80 °C and 500-600 r / min for 1-2 h, filter, wash the filter cake with deionized water until the last washing liquid is neutral, and dry it under vacuum to obtain the activated porous matrix powder.

7. The preparation method of a lithium battery cathode material applied to a drone according to claim 6, wherein, The dosage ratio of the porous matrix powder, hydrochloric acid solution and hydrogen peroxide solution is 30-40 g: 150-180 mL: 50-60 mL.

8. The preparation method of a lithium battery cathode material applied to an unmanned aerial vehicle according to claim 1, wherein, The porous matrix powder described in Step 2 is prepared by the following steps: Add styrene, divinylbenzene and deionized water into a reaction kettle, stir at 20-25 °C and 500-600 r / min for 20-30 min, then add manganese dioxide powder with a particle size of 5-10 μm, urea, benzoyl peroxide and sodium dodecylbenzenesulfonate, continue to stir for 1-2 h, filter, wash the filter cake with deionized water and absolute ethanol respectively for 2-3 times, freeze-dry and transfer it to a muffle furnace, keep it at 800-900 °C for 4-6 h under nitrogen protection, and cool it naturally to obtain the porous matrix powder.

9. The preparation method of a lithium battery cathode material applied to a drone according to claim 8, characterized in that, The dosage ratio of the styrene, divinylbenzene, deionized water, manganese dioxide powder, urea, benzoyl peroxide and sodium dodecylbenzenesulfonate is 40-50 mL: 30-40 mL: 500-600 mL: 70-80 g: 1-2 g: 4-5 g: 2-4 g.

10. A cathode material for lithium batteries applied to drones, characterized in that, Prepared by the preparation method described in any one of Claims 1-9.

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