Positive electrode composite material of secondary battery and preparation method of positive electrode composite material

Abstract

The invention provides a secondary battery positive electrode composite material and a preparation method thereof, and relates to the technical field of secondary batteries. The positive electrode composite material of the secondary battery comprises the following raw material components: A-1) active particles, A-2) a conductive agent and A-3) a binder, and the binder is asparagi polyurea. The secondary battery prepared from the positive electrode composite material disclosed by the invention has relatively good electrical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of secondary batteries and relates to a secondary battery positive electrode composite material and a preparation method thereof. Background Art

[0002] The positive electrode of a secondary battery includes a current collector and a composite material on its surface. The composite material mainly consists of active particles, a conductive agent, and a binder. The binder is a key component to maintain the stability of the positive electrode structure. The binder of the positive electrode of a secondary battery should have the following characteristics: (1) excellent electrochemical stability to prevent a series of side reactions caused by high voltage; (2) excellent mechanical properties to suppress deformation problems caused by the charge and discharge process; (3) high ionic conductivity; (4) low cost and environmental friendliness. According to the properties of the dispersion medium, the binder can be divided into oily binders and water-based binders. At present, the widely used oily binders are mainly polyvinylidene fluoride (PVDF) or polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and the water-based binders mainly include styrene-butadiene rubber (SBR) emulsion and carboxymethyl cellulose (CMC). In addition, there are also water-based binders such as polyacrylic acid (PAA), polyacrylonitrile (PAN) and polyacrylate.

[0003] However, the existing oily binder PVDF still has at least one of the following deficiencies in practical applications: insufficient stability at high temperatures, insufficient bonding performance, low ionic conductivity, limited electrochemical window, the need for specific organic solvents for dissolution, and high cost. Summary of the Invention

[0004] Aspartame polyurea, a new material, exhibits excellent properties, including good adhesion, high wear resistance, high compressive strength, excellent chemical corrosion resistance, and environmental friendliness. Furthermore, aspartame polyurea contains abundant polar functional groups such as -COC- and / or -C=O, which effectively promote ion transport and improve charge and discharge efficiency. Based on this, the present invention provides a secondary battery positive electrode composite material and a method for preparing it.

[0005] The technical solutions of the present invention are as follows:

[0006] A secondary battery positive electrode composite material comprising the following raw material components:

[0007] A-1) Active particles;

[0008] A-2) conductive agent;

[0009] A-3) binder;

[0010] The binder is aspartame polyurea.

[0011] Preferably, the weight proportion of the active particles in the secondary battery positive electrode composite material is not less than 70%;

[0012] The binder accounts for 5-20% by weight in the secondary battery positive electrode composite material;

[0013] The weight proportion of the conductive agent in the secondary battery positive electrode composite material is 10-20%.

[0014] Preferably, the active particles are selected from one or a combination of two or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, ternary materials, layered metal oxides, polyanionic compounds, Prussian blue and the like.

[0015] Preferably, the conductive agent is selected from one or a combination of two or more of carbon black, graphite, graphene, carbon nanotubes, fullerene and conductive polymers.

[0016] Preferably, the adhesive is obtained by reacting an aspartic acid ester resin and an isocyanate curing agent.

[0017] More preferably, the aspartic acid ester resin is obtained by reacting a polyamine containing polyether with one or a combination of two or more of maleate, fumarate and acrylate.

[0018] More preferably, the number average molecular weight of the polyamine is no more than 3,000.

[0019] More preferably, the isocyanate curing agent is selected from one or a combination of two or more of HDI trimer, IPDI trimer and diisocyanate compounds.

[0020] More preferably, the molar ratio of the amino groups in the aspartic acid ester resin to the NCO groups in the isocyanate curing agent is 1:1-1.2.

[0021] A method for preparing the secondary battery positive electrode composite material according to any of the above embodiments comprises mixing and dispersing the raw material components uniformly in an organic solvent, coating the mixture on a current collector, and heating and curing the mixture to obtain the secondary battery positive electrode composite material.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention uses asparagine as a binder for the positive electrode of a secondary battery, which has the following characteristics: 1) Excellent adhesion, mechanical properties and chemical corrosion resistance, which can not only effectively suppress the expansion problem caused by the positive electrode material during the charge and discharge process of the battery, but also effectively isolate the direct contact between the electrolyte and the active material, avoiding a series of side reactions, thereby improving the cycle life of the battery; 2) It contains rich polar functional groups such as -COC-, -C=O, -NHCONH-, etc., which promote the conduction of metal ions more quickly during the charge and discharge process of the battery, thereby improving the charge and discharge efficiency; 3) The curing reaction of asparagine and the adhesion to the electrode sheet are carried out simultaneously during the baking process, which can more evenly adhere the active particles and the conductive agent together to form a positive electrode composite material; 4) The polar / non-polar structure exists in the aspartic acid ester resin structure, which can better coat the active particles and the conductive agent, thereby improving the dispersion uniformity of the active particles and the conductive agent.

[0024] (2) The secondary battery obtained from the secondary battery positive electrode composite material of the present invention has good electrical performance, is suitable for positive electrode materials with different discharge voltages, and has good rate performance and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure shows a comparison of the discharge capacities of the batteries of Example 1 and Comparative Example 1 at different current densities.

[0026] Figure 2 The figure shows the cycling performance comparison of the batteries of Example 1 and Comparative Example 1 at a current density of 3C.

[0027] Figure 3 The figure shows a comparison of the cycling performance of the batteries of Example 1, Example 2 and Example 3 at a current density of 1C.

[0028] Figure 4 The figure shows the cycling performance comparison between Example 4 and Comparative Example 2 at a current density of 1C. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0030] In one aspect, the present invention provides a secondary battery positive electrode composite material comprising the following raw material components:

[0031] A-1) Active particles;

[0032] A-2) conductive agent;

[0033] A-3) binder;

[0034] The above-mentioned adhesive is aspartame polyurea.

[0035] Aspartic acid polyurea is composed of alternating isocyanate residues and aspartic acid ester residues to form a strong, highly polar polyurea backbone, forming a three-dimensional cross-linked structure with high adhesion, mechanical strength, weather resistance, and chemical resistance. The ester group in the side chain can adjust the flexibility and polarity of the material. Therefore, as a binder for positive electrode composite materials, it has the following effects: (1) effectively suppressing the expansion problem caused by the positive electrode material during the charge and discharge process of secondary batteries; (2) effectively isolating the direct contact between the electrolyte and the active material to avoid side reactions; (3) rich polar functional groups such as -COC-, -C=O, and -NHCONH- can quickly promote the conduction of metal ions during the charge and discharge process of the battery, thereby improving the charge and discharge efficiency; (4) the polar-nonpolar structure can better disperse the active particles and conductive agents.

[0036] In the present invention, the secondary battery refers to a rechargeable secondary battery, which may be a lithium ion battery, a sodium ion battery, or the like.

[0037] In some embodiments, the active particles account for no less than 70% by weight of the secondary battery positive electrode composite material;

[0038] The binder accounts for 5-20% by weight in the secondary battery positive electrode composite material;

[0039] The weight proportion of the conductive agent in the secondary battery positive electrode composite material is 10-20%.

[0040] For example, the weight proportion of active particles in the raw material components can be any value among 70%, 75%, 80%, 85%, etc. or any value between them, the weight proportion of binder can be any value among 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc. or any value between them, and the weight proportion of conductive agent can be any value among 10%, 12%, 15%, 17%, 18%, 20%, etc. or any value between them. For the raw material composition of the secondary battery positive electrode composite material of the present invention, for example, the weight proportions of active particles, binder and conductive agent can be 70%, 10% and 20%, or 75%, 15% and 10%, or 80%, 10% and 10%, or 80%, 5% and 15%, or 85%, 5% and 10%, etc.

[0041] In some embodiments, the active particles are selected from one or a combination of two or more of lithium cobalt oxide, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, ternary materials, layered metal oxides, polyanionic compounds, and Prussian blue and its analogs. Among them, lithium cobalt oxide, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, ternary materials, etc. are commonly used active particles in lithium-ion battery positive electrodes, and layered metal oxides, polyanionic compounds, and Prussian blue and its analogs are commonly used active particles in sodium-ion battery positive electrodes. For layered metal oxides, for example, layered metal oxides can be P2 structure layered positive electrode materials, O3 structure layered positive electrode materials, P3 structure layered positive electrode materials, etc.; polyanion positive electrode materials mainly include phosphates, pyrophosphates, sulfates, silicates, borates and mixed polyanions, such as olivine structure NaFePO4, niobate type NaFePO4, NASICON type structure Na3V2(PO4)3, etc.; for Prussian blue and its analogues, the structure of Prussian blue is Fe4[Fe(CN)6]3, and a molecular formula of Prussian blue analogues can be expressed as A x M[Fe(CN)6]·mH2O, where A and M represent cations (such as Li + 、Na + , K + etc.) and transition metal ions (such as Fe 3+ 、Co 2+ 、Ni 2+ 、Cu 2+ In the present invention, the active particles can be directly obtained from the market.

[0042] In some embodiments, the conductive agent is selected from one or a combination of two or more of carbon black, graphite, graphene, carbon nanotubes, fullerenes, and conductive polymers. The conductive polymer may be polyaniline and its derivatives, polypyrrole and its derivatives, polythiophene and its derivatives, or polypyrene. In the present invention, the conductive agent can be obtained directly from the market.

[0043] In some embodiments, the binder is obtained by reacting an aspartic acid ester resin and an isocyanate curing agent. Specifically, the secondary amino group in the aspartic acid ester resin reacts with the NCO group in the isocyanate curing agent to obtain aspartic acid polyurea, which is the binder of the present invention.

[0044] For aspartic acid ester resin, its structure can be shown as the following formula (1),

[0045]

[0046] Wherein, X is selected from a nonionic m-valent organic group with a number average molecular weight of 50-5000 and no more than 2 heteroatoms that is inert to isocyanate groups at 100°C, R1 and R2 are independently selected from C1-C8 alkyl groups, and m = 2-4. Aspartic acid ester resins are generally composed of the polyamine X(NH2) corresponding to X. m Obtained by reacting with maleate and / or fumarate. Aspartic acid ester resins can be directly obtained from the market, such as F420 resin, F520 resin, F220 resin, F421 resin, F221 resin, F330 resin, etc. from Feiyang Junyan Company.

[0047] For isocyanate curing agents, the average NCO group content in their molecular structure is not less than 2. Furthermore, the isocyanate curing agent is selected from one or a combination of two or more of HDI trimer, IPDI trimer, and diisocyanate compounds. Examples of diisocyanate compounds include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), and diphenylmethane diisocyanate (MDI).

[0048] For example, the isocyanate curing agent may be a single trimer such as HDI trimer, IPDI trimer, or a single diisocyanate compound, or a combination of a trimer and a diisocyanate compound, such as a combination of HDI trimer and IPDI in a weight ratio of 1:0.1-10, a combination of IPDI trimer and IPDI in a weight ratio of 1:0.1-10, a combination of HDI trimer and HMDI in a weight ratio of 1:0.1-10, a combination of IPDI trimer and HMDI in a weight ratio of 1:0.1-10, and the like.

[0049] In some embodiments, the aspartic acid ester resin is obtained by reacting a polyamine containing a polyether with one or more of maleate, fumarate, and acrylate. The use of a polyamine containing a polyether, i.e., the aforementioned X structure containing a polyether segment (e.g., a polyethylene glycol segment, a polypropylene glycol segment, a polytetrahydrofuran segment, etc.), has the following characteristics: (1) the obtained secondary battery positive electrode composite material has better flexibility and does not affect the bending or curling of the positive electrode; (2) the introduction of more -COC structures increases the polarity of the aspartic acid polyurea, which is beneficial for rapidly promoting the conduction of metal ions during the battery charge and discharge process and improving the charge and discharge efficiency; (3) the aspartic acid polyurea has a better polar-nonpolar structure, which better disperses the active particles and the conductive agent.

[0050] In some embodiments, the number average molecular weight of the polyether-containing polyamine is no more than 3000. For example, the number average molecular weight of the polyether-containing polyamine can be any value among 3000, 2800, 2500, 2200, 2000, 1800, 1500, 1300, 1200, 1000, 800, 600, 500, 300, or any value in between. The polyether-containing polyamine can further be a polyether polyamine, such as Huntsman's D230, D200, T403, D400, ED-2003, or Chenguang New Materials' CAD-2000, CAD-400, CAD-230.

[0051] In some embodiments, the molar ratio of the amino group (secondary amino group) in the aspartic acid ester resin to the NCO group in the isocyanate curing agent is 1:1-1.2. The excess of NCO groups relative to the amino group can promote the complete reaction of the amino group. For example, the molar ratio of the amino group (secondary amino group) in the aspartic acid ester resin to the NCO group in the isocyanate curing agent can be any value among 1:1, 1:1.02, 1:1.03, 1:1.05, 1:1.07, 1:1.08, 1:1.1, 1:1.12, 1:1.13, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.2, etc., or any value in between.

[0052] On the other hand, the present invention also provides a method for preparing the secondary battery positive electrode composite material described in any of the above embodiments, wherein the raw material components are mixed and dispersed uniformly in an organic solvent, then coated onto a current collector and heated to cure, thereby obtaining the secondary battery positive electrode composite material. The above organic solvent can be selected from N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), butyl acetate, dimethyl carbonate, and tetrahydrofuran. In an organic solvent, the curing reaction of aspartic acid ester resin and isocyanate curing agent is relatively slow, allowing sufficient time for the active particles and conductive agent to disperse. Specifically, one preparation method can be: adding the active particles and conductive agent to an organic solvent, and then using high-speed mechanical stirring or grinding to effectively disperse the active particles and conductive agent in the organic solvent. Then, adding the aspartic acid ester resin and isocyanate curing agent, and stirring to mix uniformly. Alternatively, a preparation method may include adding the aspartic acid ester resin to an organic solvent and stirring to disperse the mixture uniformly, then adding the active particles and the conductive agent and dispersing the mixture uniformly by high-speed mechanical stirring or grinding, and finally adding the isocyanate curing agent and stirring to mix the mixture uniformly. Alternatively, a preparation method may include adding the aspartic acid ester resin and the isocyanate curing agent to an organic solvent and stirring to disperse the mixture uniformly, then adding the active particles and the conductive agent and dispersing the mixture uniformly by high-speed mechanical stirring or grinding, to obtain the product.

[0053] In the present invention, the positive electrode sheet of the secondary battery is composed of a current collector (such as aluminum foil) and a positive electrode composite material layer. The thickness of the positive electrode composite material layer can be 10-300 μm.

[0054] The technical solution of the present invention is further described and illustrated below based on various embodiments.

[0055] Preparation Example 1-3 Preparation of aspartic acid ester resin

[0056] Preparation Example 1

[0057] The molar ratio of Huntsman ED-2003 and diethyl maleate is 1:2.

[0058] Under nitrogen protection, ED-2003 was put into a reactor, and diethyl maleate was added dropwise at room temperature. After the addition was completed, the temperature was raised to 80°C and the reaction was carried out for 160 hours to obtain polyaspartic acid resin, which was recorded as P-1.

[0059] Preparation Example 2

[0060] The molar ratio of Huntsman D400 and diethyl maleate is 1:2.

[0061] Under nitrogen protection, D400 was put into a reactor, and diethyl maleate was added dropwise at room temperature. After the addition was completed, the temperature was raised to 100°C and the reaction was carried out for 100 hours to obtain polyaspartic acid resin, which was recorded as P-2.

[0062] Preparation Example 3

[0063] The molar ratio of CAED-600 and diethyl maleate of Chenguang New Materials is 1:2.

[0064] Under nitrogen protection, CAED-600 was added to a reactor, and diethyl maleate was added dropwise at room temperature. After the addition was complete, the temperature was raised to 100°C and the reaction was carried out for 100 hours to obtain polyaspartic acid resin, which was recorded as P-3.

[0065] Example 1

[0066] The binder is composed of the polyaspartic acid resin P-1 of Preparation Example 1 and HDI trimer HT-600 in a molar ratio of amino group to NCO group of 1:1.05.

[0067] The weight ratio of the polyanionic sodium vanadium phosphate, the conductive agent Super P and the binder is 8:1:1.

[0068] Polyaspartic acid resin P-1 and HT-600 were added to NMP at a binder concentration of 5wt% and stirred to disperse uniformly. Polyanionic sodium vanadium phosphate and a conductive agent were then added and stirred at 1500 rpm for 30 minutes. The stirring speed was then reduced to 600 rpm and stirring continued for 1 hour to obtain a composite material solution. The composite material solution was coated on one side of an aluminum foil current collector and heated in a vacuum oven at 60°C for 12 hours to obtain a composite material-loaded positive electrode sheet. The average thickness of the composite material was 50 μm.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that in Example 1, the binder is replaced by PVDF-HFP of equal weight, and the remaining steps remain unchanged.

[0071] The positive electrode sheets of Example 1 and Comparative Example 1 were punched into 12mm diameter positive electrode sheets and used as positive electrodes. Hard carbon was used as negative electrode, porous glass fiber was used as separator, and 1 mol / L NaPF6 (EC / DEC+5%FEC) was used as electrolyte. Coin cells were assembled in an argon glove box with a water oxygen value below 0.1ppm, and their rate and cycle performance were tested. The performance results are shown in the attached figure. Figure 1 and attached Figure 2 shown.

[0072] In Example 1, when asparagine polyurea was used as a binder, the discharge capacities of the battery at current densities of 0.2C, 0.5C, 1C, 3C, 5C and 10C were 112.4 mAh / g, 111.7 mAh / g, 110.0 mAh / g, 107.1 mAh / g, 105.2 mAh / g and 101.4 mAh / g, respectively. In Comparative Example 1, when PVDF-HFP was used as a binder, the discharge capacities of the battery at current densities of 0.2C, 0.5C, 1C, 3C, 5C and 10C were 112.6 mAh / g, 110.5 mAh / g, 108.6 mAh / g, 105.2 mAh / g, 102.2 mAh / g and 98.4 mAh / g, respectively. Therefore, the rate performance of the battery when asparagine polyurea was used as a binder was significantly higher than that of PVDF-HFP. The cycle performance of the battery in Example 1 and the battery in Comparative Example 1 is shown in FIG. Figure 2 As shown in the graph, the capacity retention rate of the battery in Example 1 after 300 cycles at a current density of 3C is 93.4%, which is much higher than 88.4% of the battery in Comparative Example 1, indicating that aspartame as a binder is also significantly better than PVDF-HFP in battery cycle performance.

[0073] Example 2

[0074] The difference between this embodiment and embodiment 1 is that in embodiment 1, the weight ratio of polyanionic sodium vanadium phosphate, conductive agent Super P, and binder is adjusted from 8:1:1 to 7:1:2. The remaining steps remain unchanged.

[0075] Example 3

[0076] The difference between this embodiment and embodiment 1 is that in embodiment 1, the weight ratio of polyanionic sodium vanadium phosphate, conductive agent Super P, and binder is adjusted from 8:1:1 to 8.5:1:0.5. The remaining steps remain unchanged.

[0077] The positive electrodes of Examples 2 and 3 were prepared into button-type batteries according to the method of Example 1. The discharge specific capacities of the button-type batteries obtained in Examples 1, 2 and 3 at a current density of 1C were 110.6 mAh / g, 106.8 mAh / g and 104.4 mAh / g, respectively. After 100 cycles, the retention rates were 97.2%, 96.1% and 96.5%, respectively. Figure 3 Furthermore, comparing the electrical performance results of Examples 1-3, it can be seen that a suitable amount of binder helps to better disperse the active particles and the conductive agent, thereby obtaining a battery with better performance.

[0078] Example 4

[0079] The isocyanate curing agent is composed of HDI trimer HT-600 and HDI in a weight ratio of 3:1. The adhesive is composed of the polyaspartic acid resin P-2 of Preparation Example 2 and the isocyanate curing agent in a molar ratio of amino group to NCO group of 1:1.08.

[0080] The weight ratio of sodium nickel iron manganese oxide layered oxide, conductive agent Super P and binder is 7.5:1:1.5.

[0081] Polyaspartic acid resin P-1 and HT-600 were added to NMP at a binder concentration of 5wt% and stirred to disperse uniformly. Sodium nickel iron manganese oxide and a conductive agent were then added and stirred at 1500 rpm for 30 minutes. The stirring speed was then reduced to 600 rpm and stirring continued for 1 hour to obtain a composite material solution. The composite material solution was coated on one side of an aluminum foil current collector and heated in a vacuum oven at 60°C for 12 hours to obtain a composite material-loaded positive electrode sheet. The average thickness of the composite material was 80 μm.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 4 is that in Example 4, the binder is replaced by PVDF-HFP of equal weight, and the remaining steps remain unchanged.

[0084] The positive electrodes of Example 4 and Comparative Example 2 were prepared into button type batteries according to the method of Example 1. The comparison results of electrical performance are shown in the attached figure. Figure 4 As shown in the figure, the capacity retention rates of the batteries of Example 4 and Comparative Example 2 after 160 cycles at a current density of 1C are 83.4% and 77.1%, respectively. Therefore, the cyclic stability of the present invention using aspartame as a binder in a high-voltage battery system is also significantly better than that of PVDF-HFP.

[0085] Example 5

[0086] The difference between this example and Example 4 is that in Example 4, the polyaspartic acid resin P-2 is replaced by the polyaspartic acid resin P-3 of Preparation Example 3 having the same molar amino group. The remaining steps remain unchanged.

[0087] Example 6

[0088] The difference between this embodiment and embodiment 4 is that in embodiment 4, the polyaspartic acid resin P-2 is replaced by F420 resin of Feiyang Junyan Co., Ltd. having the same molar amino group. The remaining steps remain unchanged.

[0089] The positive electrodes of Example 5 and Example 6 were respectively prepared into button-type batteries according to the method of Example 1. The capacity retention rates of the batteries of Example 5 and Example 6 after 160 cycles at a current density of 1 C were 83.1% and 80.7%, respectively.

[0090] As described above, the basic principles, main features, and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A secondary battery positive electrode composite material, characterized in that: Contains the following raw materials: A-1) Active particles; A-2) conductive agent; A-3) binder; The binder is aspartame polyurea.

2. The secondary battery positive electrode composite material according to claim 1, characterized in that The active particles account for no less than 70% by weight of the secondary battery positive electrode composite material; The binder accounts for 5-20% by weight in the secondary battery positive electrode composite material; The weight proportion of the conductive agent in the secondary battery positive electrode composite material is 10-20%.

3. The secondary battery positive electrode composite material according to claim 1, characterized in that The active particles are selected from one or a combination of two or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, ternary materials, layered metal oxides, polyanionic compounds, Prussian blue and the like.

4. The secondary battery positive electrode composite material according to claim 1, characterized in that The conductive agent is selected from one or a combination of two or more of carbon black, graphite, graphene, carbon nanotubes, fullerene and conductive polymers.

5. The secondary battery positive electrode composite material according to claim 1, characterized in that: The adhesive is obtained by reacting aspartic acid ester resin and isocyanate curing agent.

6. The secondary battery positive electrode composite material according to claim 5, characterized in that: The aspartic acid ester resin is obtained by reacting a polyamine containing polyether with one or a combination of two or more of maleate, fumarate and acrylate.

7. The secondary battery positive electrode composite material according to claim 6, characterized in that: The number average molecular weight of the polyamine is no more than 3,000.

8. The secondary battery positive electrode composite material according to claim 5, characterized in that The isocyanate curing agent is selected from one or a combination of two or more of HDI trimer, IPDI trimer and diisocyanate compounds.

9. The secondary battery positive electrode composite material according to claim 5, characterized in that: The molar ratio of the amino groups in the aspartic acid ester resin to the NCO groups in the isocyanate curing agent is 1:1-1.

2.

10. A method for preparing the secondary battery positive electrode composite material according to any one of claims 1 to 9, characterized in that: The raw material components are mixed and dispersed uniformly in an organic solvent, and then coated on a current collector, and heated and cured to obtain the secondary battery positive electrode composite material.

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