Conjugated organic framework modified and regulated electrode material as well as preparation method and application thereof

Abstract

The invention discloses a conjugated organic framework modified and regulated electrode material as well as a preparation method and application thereof, and belongs to the technical field of chemical power sources. By doping the conjugated organic framework, the problems of poor stability and low safety of the high-nickel positive electrode are solved. The high-nickel ternary material is ensured to have good cycle performance, thermal stability and safety while the energy density is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical power sources, and in particular relates to an electrode material modified and regulated by a conjugated organic skeleton, and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy technologies, lithium-ion batteries have attracted widespread attention as efficient and environmentally friendly energy storage devices. High-nickel cathode materials, due to their high specific capacity and high energy density, are considered one of the most promising cathode materials for next-generation lithium-ion batteries. However, high-nickel cathode materials still face many challenges in practical applications, mainly in the following aspects:

[0003] Li / Ni mixing problem: Li / Ni mixing often occurs during the synthesis and charge-discharge process of high nickel cathode materials. + and Ni 2+ The ionic radius of Ni 2+ It is easy to occupy the vacancies in the Li layer, resulting in Li + The migration channels of the materials are blocked, resulting in irreversible capacity loss and a decrease in rate performance. In addition, the mixing phenomenon can also cause thermal instability, further exacerbating the structural degradation of the material.

[0004] Lattice oxygen loss: During high-voltage charging, the lattice oxygen in the high-nickel cathode material easily migrates from the bulk to the surface and precipitates, resulting in irreversible loss of lattice oxygen. This oxygen loss not only reduces the specific capacity of the material, but also causes the structural collapse and voltage decay of the cathode material. For example, in nickel-rich cathode materials, the precipitation of oxygen will promote the oxidative decomposition of the electrolyte, forming a passivation layer, which further hinders the Li + insertion and removal.

[0005] Lattice distortion and mechanical degradation: During the charge and discharge process, high-nickel cathode materials are prone to lattice distortion and particle breakage due to volume changes and lattice stress. These mechanical degradation phenomena increase the structural instability of the material, thereby affecting the cycle life and rate performance of the battery.

[0006] Surface side reactions: Complex side reactions occur between the surface of high-nickel cathode materials and the electrolyte, forming a thick cathode-electrolyte interface (CEI) layer. These side reactions not only consume active lithium but also increase the internal resistance of the battery, further reducing battery performance.

[0007] Problems such as Li / Ni mixing, lattice oxygen loss, lattice distortion, and surface side reactions in high-nickel cathode materials seriously affect the irreversible capacity, cycle stability, and rate performance of lithium-ion batteries. Therefore, developing a technical solution that can effectively address these issues is of great significance for improving the performance of high-nickel cathode materials and promoting the development of lithium-ion battery technology. Summary of the Invention

[0008] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0009] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0010] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing an electrode material modified and regulated by a conjugated organic skeleton.

[0011] In order to solve the above technical problems, the present invention provides the following technical solutions, including:

[0012] After the conjugated organic framework, NCM811, conductive carbon and binder are evenly mixed, a solvent is added to make a slurry, which is coated on aluminum foil to form a uniform reaction covering, and vacuum dried to obtain an electrode material modified and regulated by the conjugated organic framework;

[0013] The mass ratio of the conjugated organic framework, NCM811, conductive carbon and binder is 0.25-1:150-250:20-30:20-30.

[0014] As a preferred embodiment of the method for preparing the electrode material modified and regulated by the conjugated organic skeleton of the present invention, the conjugated organic skeleton contains a cyano functional group.

[0015] As a preferred embodiment of the method for preparing the electrode material modified and regulated by the conjugated organic skeleton of the present invention, the method for preparing the conjugated organic skeleton comprises:

[0016] Triethylamine is added to a mixed solution of HHTP and TFTPN in dioxane, followed by freezing at 77-120K and vacuum flame sealing to obtain a sealed tube. The sealed tube is heated for reaction, separated, and washed to obtain a yellow precipitate. The yellow precipitate is immersed in 50-75 mL of DMF for 24-36 hours, THF for 24-36 hours, and acetone for 24-36 hours, with the solvent changed 4-7 times daily to remove impurities in the pores. The conjugated organic framework is then dried at 80-100°C in vacuum to obtain a CN-JOC COF.

[0017] The molar ratio of HHTP, TFTPN, dioxane and triethylamine is 4-5:6-7:1000-1500:30.

[0018] As a preferred embodiment of the method for preparing the electrode material modified and regulated by the conjugated organic framework of the present invention, the heating reaction is carried out at a heating temperature of 120 to 160° C. and a heating time of 2 to 3 days.

[0019] As a preferred embodiment of the preparation method of the electrode material modified and regulated by the conjugated organic framework of the present invention, the average particle size of the NCM811 is 600-800 nm, and the theoretical density is 2.94-3.15 g·cm -3 .

[0020] As a preferred embodiment of the method for preparing the electrode material modified and regulated by the conjugated organic framework of the present invention, the conductive carbon includes one or more of carbon black, Super P, and acetylene black; and the binder includes one or more of PVDF and sodium alginate.

[0021] As a preferred embodiment of the method for preparing the electrode material modified and regulated by the conjugated organic framework of the present invention, the thickness of the reaction covering is 200 to 220 μm.

[0022] As a preferred solution of the preparation method of the conjugated organic framework modified and regulated electrode material of the present invention, the solvent includes one or more of NMP, DMF, and DMSO; and the solvent accounts for 83-95% of the volume of the entire slurry.

[0023] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an electrode material modified and regulated by a conjugated organic skeleton.

[0024] The purpose of the present invention is to overcome the deficiencies in the prior art and provide an application of an electrode material modified and regulated by a conjugated organic skeleton, and to apply the electrode material modified and regulated by a conjugated organic skeleton to a lithium ion battery.

[0025] Beneficial effects of the present invention:

[0026] (1) The present invention prepares an electrode material modified and regulated by a conjugated organic skeleton, which is applied to batteries and exhibits excellent cycle performance and rate performance.

[0027] (2) The present invention effectively improves the interface stability of high-nickel ternary materials, while also having good cycle performance, thermal stability and safety.

[0028] (3) The modification process of the present invention is simple and only requires simple stirring. It is low-cost and has a small amount of doping. The raw materials are cheap, the equipment is simple, the energy consumption is low, the time is short, and the safety is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort. Among them:

[0030] Figure 1 IR spectra of HHTP, TFTPN and CN-JOC COF prepared in Example 1.

[0031] Figure 2 This is the Raman test image of the CN-JOC COF prepared in Example 1.

[0032] Figure 3 This is the nitrogen adsorption and desorption curve of the CN-JOC COF prepared in Example 1.

[0033] Figure 4 This is a test diagram of the cycle performance of a half-cell assembled from the positive electrode sheets prepared in Example 1 and Comparative Example 1 at a charge and discharge cut-off voltage of 4.3V.

[0034] Figure 5 The rate performance of the half-cell assembled from the positive electrode sheets prepared in Example 1 and Comparative Example 1.

[0035] Figure 6 CV test graphs of half-cells assembled from the positive electrode sheets prepared in Example 1(a) and Comparative Example 1(b) at 0.1, 0.2, 0.3, 0.4, and 0.5 mV / s;

[0036] Figure 7 It is the AC impedance diagram of the half-cell assembled from Example 1(a) and Comparative Example 1(b) and Comparative Example 1 before and after cycling at a voltage of 3-4.3V and a current of 0.2C.

[0037] Figure 8It is an SEM morphology of the positive electrode sheet and the negative electrode surface after the half-battery cycle assembled from Example 1, Comparative Example 1 and Comparative Example 1, wherein a is the positive electrode side of Comparative Example 1, b is the negative electrode side of Comparative Example 1, c is the positive electrode side of Example 1, and d is the negative electrode side of Example 1.

[0038] Figure 9 Surface chemical information characterization diagrams of the two materials of Example 1 and Comparative Example 1 after 100 cycles, wherein a is the XPS C spectrum of Comparative Example 1, b is the XPS C spectrum of Example 1, c is the XPS O spectrum of Comparative Example 1, and d is the XPS O spectrum of Example 1. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0042] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0043] The materials of the present invention and their abbreviations are as follows:

[0044] NCM811 is a ternary cathode material with a nickel:cobalt:manganese ratio of 8:1:1, hexahydroxytriphenylene (HHTP), tetrafluoroterephthalonitrile (TFTPN), dimethylformamide (DMF), tetrahydrofuran (THF), polyvinylidene fluoride (PVDF), N-methylpyrrolidone (NMP) N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0045] The electrochemical performance of the materials prepared in the examples of the present invention was tested as follows:

[0046] The electrode material synthesized by the method of the present invention is cut into positive electrode sheets, and assembled in a glove box in the order of negative electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, positive electrode sheet, negative electrode shell, gasket, and spring, sealed, and allowed to stand in an oven at 30°C for 48 hours to obtain a battery.

[0047] Example 1

[0048] This embodiment provides a method for preparing an electrode material modified and regulated by a conjugated organic framework, specifically:

[0049] To a mixed solution of HHTP (32.3 mg, 0.10 mmol) and TFTPN (25.5 mg, 0.12 mmol) in dioxane (2.0 mL) was added triethylamine (83.6 μL, 0.60 mmol) (i.e., the molar ratio of HHTP, TFTPN, dioxane, and triethylamine was 5:6:1135:30). The mixed aqueous solution was then transferred to a test tube and the test tube was frozen at 77 K (liquid nitrogen bath). The tube was then flame-sealed under vacuum. The sealed tube was heated at 120°C for three days. After cooling to room temperature, the resulting yellow precipitate was isolated and washed three times with dimethylformamide (DMF), ultrapure water, tetrahydrofuran (THF), and acetone. The resulting solid was immersed in 50.0 mL of DMF for 24 hours, THF for 24 hours, and acetone for 24 hours, respectively, with the solvent changed four times daily during this period. Finally, the precipitate was dried under vacuum at 80 °C overnight to obtain pure yellow solid CN-JOC COF.

[0050] The two raw materials HHTP, TFTPN and the prepared CN-JOC COF were subjected to infrared testing. The results are as follows Figure 1 As shown in Figure 3, the weakening of the C=N characteristic peak and the shift of the CO characteristic peak can be found, which proves the successful synthesis of CN-JOC COF. Figure 2 The Raman test further proves that the synthesized product has good Figure 3 The BET test demonstrated that the synthesized CN-JOC COF had a good pore structure.

[0051] 2 mg of prepared CN-JOC COF powder and 0.4 g of particles with an average particle size of 600 nm and a theoretical density of 2.94 g·cm -3 NCM811, 0.05g carbon black and 0.05g PVDF (i.e., the mass ratio of CN-JOC COF, NCM811, carbon black and PVDF is 1:200:25:25) were put into a mortar and ground for 2h. The ground mixture was placed in a vial and 2mL of anhydrous NMP solvent was added and stirred for 24h (i.e., the solvent accounted for 91% of the volume of the entire slurry). The slurry was then poured onto the rough surface of aluminum foil for coating. The film thickness was controlled at 200μm. The coated electrode was placed in a vacuum oven at 100℃ and baked for 24h. The dried electrode was cut into small discs with a diameter of 12mm using a punch to obtain a positive electrode.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the addition amount of CN-JOC COF is adjusted to 0, and the rest of the preparation process is the same as that of Example 1 to prepare a positive electrode sheet.

[0054] The assembled batteries were clamped on the Xinwei test channel with battery clips, and the rate and cycle performance tests of the two system half-cells were carried out in the voltage range of 3-4.3V. Figure 4 The cycling performance of the two half-cell systems was tested at a charge-discharge cutoff voltage of 4.3V. At a current of 0.2C, the NCM / PVDF half-cell maintained 60% of its capacity after 200 cycles. Meanwhile, the NCM / COF half-cell maintained 85% of its capacity after 200 cycles. This is because the addition of CN-JOCCOF effectively inhibits the irreversible phase transition from H2 to H3, stabilizing the cathode structure and improving cycling stability.

[0055] The rate test results of the two half-cell systems are as follows: Figure 5 As shown in the figure, the discharge capacity of the NCM811 half-cell shows a rapid decay trend with the increase of current and the capacity is irreversible, while the half-cell with PIS as the binder can fully recover to the discharge capacity at a current of 0.2C after 35 cycles, showing good capacity reversibility. In addition, compared with the NCM811 half-cell at a rate of 75mA hg -1 Compared with the discharge specific capacity of NCM / COF, the reversible specific capacity of NCM / COF is 160mA hg -1 The above results indicate that CN-JOC COF can stabilize the cathode structure at high current, inhibit irreversible phase transition, and improve the rate performance of NCM811 electrode. Figure 4 and Figure 5 It can also be seen that the cycle performance and rate performance of the NCM811 electrode prepared in Comparative Example 1 are poor.

[0056] The assembled battery was clamped on the electrochemical workstation with a battery fixture, and CV tests were performed in the order of 0.1, 0.2, 0.3, 0.4, and 0.5 mV / s, and the frequency was set to 0.001-10000 for impedance testing.

[0057] The test results are as follows Figure 6 As shown in a and b, it can be seen that the redox peak shape of the CV curve is significantly improved after the addition of CN-JOC COF, and the lithium ion diffusion capacity is also greatly improved. Figure 7a, b are AC impedance diagrams of different half-cell systems before and after cycling at a high voltage of 4.7V and a current of 0.2C. The semicircle in the high-frequency region represents the electrode / electrolyte interface film impedance (Rf), and the semicircle in the low-frequency region represents the charge transfer impedance (Rct). Analysis shows that the initial Rct of the NCM / COF NCM811 and half-cells are 50Ω and 180Ω, respectively. Obviously, the addition of CN-JOU COF can effectively improve the permeability of lithium ions, thereby reducing the lithium ion transmission barrier. After 100 cycles, the Rct of the NCM / COF and NCM811 half-cells increased significantly. The reason for the sharp increase in resistance is the strong polarization of the electrodes under high voltage. The Rf of the NCM / COF half-cell after cycling is 200Ω, which is significantly lower than the Rf of NCM811 (480Ω). This indicates that the NCM811 electrode with the addition of CN-JOU COF has good structural stability and ion pathways at high voltages. It also shows that the coating layer formed by COF has a reinforcing effect on the electrode / electrolyte interface, which can reduce the redox reaction caused by the electrolyte. Figure 6 and Figure 7 It can be found that the peaks obtained from the CV test of the NCM811 electrode prepared in Comparative Example 1 are relatively messy and the peak shape is very poor, and the impedance value is relatively high.

[0058] The cycled battery was disassembled with a battery disassembly machine and cleaned with DME solvent. The cleaned pole pieces and lithium sheets were subjected to SEM testing. The results are as follows: Figure 8 As shown in the SEM morphology of the positive electrode surface after cycling, the NCM811 electrode shows obvious secondary particle cracking and pulverization, as well as surface roughness. This is due to severe interfacial side reactions during the cycling process. This secondary particle surface roughness is not observed in the NCM / COF electrode, indicating that during long-cycle charge and discharge, the porous structure of CN-JOC COF can avoid structural fragmentation and interfacial side reactions caused by stress concentration during repeated charge and discharge. Figure 8 It can also be found that the surface of the NCM811 electrode after cycling is very rough, proving that the side reaction at the interface is very intense.

[0059] XPS test was used to characterize the surface chemical information of the two materials after 100 cycles. The results are as follows: Figure 9As shown. Deconvolution of the C1s spectrum can be divided into peaks corresponding to C–F, C=O, C–O, and C–C bonds. The C–F chemical bond corresponds to the binder PVDF, the C–C peak at 284.8 eV can be attributed to conductive carbon black, and the C–O and C=O peaks correspond to side reaction products on the electrode surface, primarily decomposition products of the carbonate electrolyte solvent at high voltage during cycling. Corresponding peaks appear at 531.6 eV (C=O) and 533.2 eV (C–O) in the O1s spectrum. Compared to NCM811, the NCM811 / COF electrode exhibits relatively weak C–O and C=O peaks, indicating that side reactions at the cathode / electrolyte interface caused by the decomposition of the carbonate solvent are effectively suppressed. This demonstrates that the CN-JOC COF significantly suppresses interfacial side reactions. It can also be found that the side reaction products C–O and C=O peaks corresponding to the electrode surface in NCM811 prepared in Comparative Example 1 are stronger, indicating that the side reaction at the cathode / electrolyte interface caused by the decomposition of the carbonate solvent is more intense.

[0060] Example 2

[0061] The difference between this embodiment and embodiment 1 is that the mass of CN-JOC COF powder is adjusted to 1 mg, that is, the mass ratio of CN-JOCCOF, NCM811, carbon black and PVDF is 0.5:200:25:25. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0062] Example 3

[0063] The difference between this embodiment and embodiment 1 is that the mass of CN-JOC COF powder is adjusted to 0.5 mg, that is, the mass ratio of CN-JOCCOF, NCM811, carbon black and PVDF is 0.25:200:25:25. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0064] Example 4

[0065] The difference between this embodiment and embodiment 1 is that the mass of CN-JOC COF powder is adjusted to 3 mg, that is, the mass ratio of CN-JOCCOF, NCM811, carbon black and PVDF is 1.5:200:25:25. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0066] The positive electrode sheets prepared in the above embodiment were assembled into half-cells for electrochemical performance testing. The results compared with those in Example 1 are shown in Table 1.

[0067] Table 1

[0068]

[0069]

[0070] As can be seen from the table above, adjusting the content of CN-JOC COF powder in the positive electrode sheet has a significant impact on the performance of the half-cell. This is because CN-JOC COF can inhibit interfacial side reactions. Too much or too little content will weaken its inhibitory effect, thereby causing poor battery performance. According to the results in the table above, the best technical effect can be achieved when the mass ratio of the conjugated organic framework, NCM811, conductive carbon, and binder in the present invention is 1:200:25:25.

[0071] Example 5

[0072] The difference between this embodiment and embodiment 1 is that the volume of the anhydrous NMP solvent is adjusted to 1 mL, that is, the solvent accounts for 83% of the volume of the entire slurry. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0073] Example 6

[0074] The difference between this embodiment and embodiment 1 is that the volume of the anhydrous NMP solvent is adjusted to 3 mL, that is, the solvent accounts for 94% of the entire slurry volume. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0075] Example 7

[0076] The difference between this embodiment and embodiment 1 is that the volume of the anhydrous NMP solvent is adjusted to 4 mL, that is, the solvent accounts for 95% of the volume of the entire slurry. The rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0077] The positive electrode sheets prepared in the above examples were assembled into half-cells for electrochemical performance testing. The results compared with those in Example 1 are shown in Table 2.

[0078] Table 2

[0079] Volume ratio of solvent Capacity retention rate% (200 cycles) Example 1 91％ 80.7 Example 5 83％ 76.6 Example 6 94％ 75.1 Example 7 95％ 67.8

[0080] It can be seen from the above table that adjusting the solvent volume of the positive electrode slurry has a significant effect on the performance of the half-cell. This is because after adjusting the volume of anhydrous NMP, the viscosity is too low, which affects the stability of the positive electrode slurry. According to the results in the above table, the best technical effect can be obtained when the volume ratio of anhydrous NMP to the volume of the slurry is 91%.

[0081] Example 8

[0082] The difference between this embodiment and embodiment 1 is that the grinding time is adjusted to 1 hour, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0083] Example 9

[0084] The difference between this embodiment and embodiment 1 is that the grinding time is adjusted to 0.5 h, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0085] The positive electrode sheets prepared in the above examples were assembled into half-cells for electrochemical performance testing. The results compared with those in Example 1 are shown in Table 3.

[0086] Table 3

[0087] Grinding time Capacity retention rate% (200 cycles) Example 1 2h 80.7 Example 8 1h 73.2 Example 9 0.5h 60

[0088] As can be seen from the above table, adjusting the grinding time has a significant impact on the performance of the half-cell. This is because the adjustment of the grinding time leads to uneven mixing of the various components. According to the results in the above table, the best technical effect can be obtained when the grinding time in the present invention is 2 hours.

[0089] Example 10

[0090] The difference between this embodiment and embodiment 1 is that the slurry stirring time is adjusted to 18 hours, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0091] Example 11

[0092] The difference between this embodiment and embodiment 1 is that the slurry stirring time is adjusted to 12 hours, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0093] The positive electrode sheets prepared in the above examples were assembled into half-cells for electrochemical performance testing. The results compared with those in Example 1 are shown in Table 4.

[0094] Table 4

[0095] Slurry stirring time Capacity retention rate% (200 cycles) Example 1 24h 80.7 Example 10 18h 71.8 Example 11 12h 66.8

[0096] It can be seen from the above table that adjusting the slurry stirring time has a significant impact on the performance of the half-cell. This is because changing the slurry stirring time causes the various components to be dispersed less evenly in the solution. According to the results in the above table, the best technical effect can be obtained when the slurry stirring time in the present invention is 24h.

[0097] Example 12

[0098] The difference between this embodiment and embodiment 1 is that the thickness of the reaction cover is adjusted to 180 μm, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0099] Example 13

[0100] The difference between this embodiment and embodiment 1 is that the thickness of the reaction cover is adjusted to 220 μm, and the rest of the preparation process is the same as that of embodiment 1 to prepare a positive electrode sheet.

[0101] The positive electrode sheets prepared in the above examples were assembled into half-cells for electrochemical performance testing. The results compared with those in Example 1 are shown in Table 5.

[0102] Table 5

[0103] Thickness of reaction cover Capacity retention rate% (200 cycles) Example 1 200μm 80.7 Example 12 180μm 82 Example 13 220μm 70.3

[0104] As can be seen from the table above, adjusting the coating thickness results in changes in electrode loading. Excessively high loading increases ion transport resistance, leading to performance degradation. While excessively low loading slightly improves capacity retention, it significantly reduces the overall battery energy density. Based on the results in the table above, the optimal technical effect is achieved when the reaction coating thickness is 200 μm.

[0105] Comparative Example 2

[0106] 2,5-Dihydroxyterephthalic acid (1.82 mmol, 0.361 g) and cobalt nitrate hexahydrate (6.502 mmol, 1.893 g) were dissolved in a uniform mixture of N,N-dimethylformamide-ethanol-water (v:v:v, 1:1:1, 150 mL) and sonicated for uniform dissolution. The solution was transferred to a Teflon-lined autoclave and placed in an oven at 100°C for 24 h. After 24 h, the autoclave was removed and allowed to cool to room temperature. The sample was collected under air and washed with methanol. The synthesized Co-MOF-74 sample was activated in an appropriate amount of anhydrous methanol, with fresh methanol replaced every 12 h. The sample was soaked for 72 h and filtered at room temperature.

[0107] NCM811, carbon black, and PVDF were mixed in NMP at a ratio of 90:5:5, and 5 wt% of Co-MOF-74 was added. The mixture was coated on aluminum foil, and the electrode loading density was controlled to be about 8 mg cm -2 The cells were dried in a vacuum oven at 150°C for 12 hours. The dried electrodes were punched into 12mm diameter discs. A 2032-type button cell was assembled using the cut electrodes as the positive electrode, lithium metal as the negative electrode, PP as the separator, and the electrolyte as the electrolyte. The cells were then tested for 200 cycles at 30°C, with a current of 0.1C to a voltage between 3 and 4.3V.

[0108] Comparative Example 3

[0109] NCM811 and ammonium bicarbonate were mixed at a mass ratio of 100:1. The mixture was then transferred to a quartz tube and evacuated to 1.0×10 -3Pa and flame sealed. The sealed quartz tube was heated at 300 °C for 15 min. The modified NCM811, carbon black, and PVDF were mixed in NMP at a ratio of 8:1:1. The mixture was coated on aluminum foil, and the electrode loading density was controlled to be about 8 mg cm -2 The cells were dried in a vacuum oven at 150°C for 12 hours. The dried electrodes were punched into 12mm diameter discs. A 2032-type button cell was assembled using the cut electrodes as the positive electrode, lithium metal as the negative electrode, PP as the separator, and the electrolyte as the electrolyte. The cells were then tested for 200 cycles at 30°C, with a current of 0.1C to a voltage between 3 and 4.3V.

[0110] Comparative Example 4

[0111] 1 g NCM positive electrode material, 0.01 g nano-Al2O3 and 10 mL of anhydrous ethanol were added to a beaker, mixed by ultrasonic dispersion method for 1 h, stirred for 20 h, dried at 60 ° C for 20 h, and calcined at 450 ° C for 10 h under argon atmosphere to obtain an Al2O3-coated NCM material with a mass fraction of 1%, which was recorded as NCM@Al2O3.

[0112] NCM@Al2O3, carbon black, and PVDF were mixed in NMP at a ratio of 8:1:1, and the mixture was coated on aluminum foil. The electrode loading density was controlled to be about 8 mg cm -2 The electrodes were then dried in a vacuum oven at 150°C for 12 hours. The dried electrodes were then cut into 12mm diameter discs using a punch. A 2032-type button cell was assembled using the cut electrodes as the positive electrode, lithium metal as the negative electrode, PP as the separator, and the electrolyte as the electrolyte. The cells were then tested for 200 cycles at 30°C, with a current of 0.1C to a voltage between 3 and 4.3V.

[0113] Comparative Example 5

[0114] Dicyandiamide (99.9%, Aladdin) was dissolved in 50 mL of anhydrous ethanol (99.5%, Aladdin). Subsequently, the NCM811 positive electrode was slowly added to the solution and ball milled for 12 hours at a ball-to-material ratio of 10:1 and a rotation speed of 100 r / min. Then, the obtained product was dried at 80°C for 12 hours, placed in a sealed crucible and heated to 350°C and maintained for 1 hour to ensure that the dicyandiamide was fully vaporized. Finally, they were further heated to 500°C and maintained for 1 hour to decompose the dicyandiamide on the surface and form C3N4. The C3N4(CN)-coated NCM9055 sample (denoted as NCM811@CN) was synthesized.

[0115] NCM811@CN, carbon black, and PVDF were mixed in NMP at a ratio of 8:1:1, and the mixture was coated on aluminum foil to control the electrode loading density to be approximately 8 mg cm-2 The electrodes were then dried in a vacuum oven at 150°C for 12 hours. The dried electrodes were then cut into 12mm diameter discs using a punch. A 2032-type button cell was assembled using the cut electrodes as the positive electrode, lithium metal as the negative electrode, PP as the separator, and the electrolyte as the electrolyte. The cells were then tested for 200 cycles at 30°C, with a current of 0.1C to a voltage between 3 and 4.3V.

[0116] The positive electrode sheets prepared in the above comparative example were assembled into half-cells and subjected to electrochemical performance tests. The results were compared with those of Example 1 and are shown in Table 6.

[0117] Table 6

[0118] Capacity retention rate% (200 cycles) Example 1 CN-JOCCOF modification 80.7 Comparative Example 2 Co-MOF-74 modification 78.2 Comparative Example 3 <![CDATA[NH4HCO3 shell modification]]> 72.6 Comparative Example 4 <![CDATA[Surface Coating of Nano-Al2O3]]> 68.7 Comparative Example 5 <![CDATA[Surface modification of C3N4]]> 63.8

[0119] It can be seen from the above table that the NCM811 cathode material modified with the conjugated organic framework CN-JOC COF has the best modification effect and the best cycle stability.

[0120] In summary, the present invention has produced an electrode material modified and regulated by a conjugated organic framework, which, when applied to batteries, exhibits excellent cycling and rate performance. This effectively improves the interfacial stability of high-nickel ternary materials while also exhibiting good cycling performance, thermal stability, and safety.

[0121] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing an electrode material modified and regulated by a conjugated organic framework, characterized in that: include, After the conjugated organic framework, NCM811, conductive carbon and binder are evenly mixed, a solvent is added to make a slurry, which is coated on aluminum foil to form a uniform reaction covering, and vacuum dried to obtain an electrode material modified and regulated by the conjugated organic framework; The mass ratio of the conjugated organic framework, NCM811, conductive carbon and binder is 0.25-1:150-250:20-30:20-30.

2. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 1, wherein: The conjugated organic skeleton contains a cyano functional group.

3. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 2, wherein: The preparation method of the conjugated organic framework comprises: Triethylamine is added to a mixed solution of HHTP and TFTPN in dioxane, followed by freezing at 77-120K and vacuum flame sealing to obtain a sealed tube. The sealed tube is heated for reaction, separated, and washed to obtain a yellow precipitate. The yellow precipitate is immersed in 50-75 mL of DMF for 24-36 hours, THF for 24-36 hours, and acetone for 24-36 hours, with the solvent changed 4-7 times daily to remove impurities in the pores. The conjugated organic framework is then dried at 80-100°C in vacuum to obtain a CN-JOC COF. The molar ratio of HHTP, TFTPN, dioxane and triethylamine is 4-5:6-7:1000-1500:

30.

4. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 3, wherein: The heating reaction has a heating temperature of 120 to 160° C. and a heating time of 2 to 3 days.

5. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 1, wherein: The average particle size of NCM811 is 600-800 nm, and the theoretical density is 2.94-3.15 g·cm -3 .

6. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 1, wherein: The conductive carbon includes one or more of carbon black, Super P, and acetylene black; the binder includes one or more of PVDF and sodium alginate.

7. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 1, wherein: The thickness of the reaction cover is 200-220 μm.

8. The method for preparing an electrode material modified and regulated by a conjugated organic framework according to claim 1, wherein: The solvent includes one or more of NMP, DMF and DMSO; the solvent accounts for 83-95% of the volume of the entire slurry.

9. An electrode material modified and regulated by a conjugated organic skeleton prepared by the preparation method according to any one of claims 1 to 8.

10. An application of the electrode material modified and regulated by the conjugated organic framework according to claim 9, characterized in that: The electrode material modified and regulated by the conjugated organic framework is applied to lithium-ion batteries.

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