Lithium-ion battery positive electrode material and preparation method thereof, positive electrode sheet

Abstract

This application discloses a lithium-ion battery positive electrode material, a preparation method, and a positive electrode sheet, relating to the field of electrode materials. The positive electrode material has the structural formula shown in Formula I below: wherein R1 is an aromatic nucleus, at least two of R2, R3, R4, and R5 are acridinium groups / acridine derivative groups, and the remainder are hydrogen atoms. This application has the effect of improving the energy density, power density, and cycle life of lithium-ion batteries using organic electrode materials.

Description

Technical Field

[0001] The present application relates to the field of electrode materials, and in particular to a lithium-ion battery positive electrode material, a preparation method thereof, and a positive electrode sheet. Background Art

[0002] Lithium-ion batteries, with their advantages of high energy density, long cycle life, and environmental friendliness, dominate the portable electronics market and show great promise in large-scale applications such as electric vehicles (EVs) and smart grids.

[0003] At present, lithium-ion batteries mainly use transition metal oxides or phosphates as positive electrodes, such as LiCoO2, LiMn2O4, LiFePO4 or LiNi x Mn y Co z O2, etc., have high energy density, good conductivity and stable structure, and are widely used in life. Organic electrode materials are widely available, have designable structures, are not restricted by ion types, and are resource-sustainable and environmentally friendly.

[0004] However, inorganic electrode materials are often derived from non-renewable ores, while existing organic electrode materials have limited performance in terms of energy density, power density and cycle life. Summary of the Invention

[0005] In view of the deficiencies of the above-mentioned related technologies, the present application provides a lithium-ion battery positive electrode material and a preparation method thereof, and a positive electrode sheet.

[0006] In the first aspect, the present application provides a lithium-ion battery positive electrode material using the following technical solution:

[0007] A lithium-ion battery positive electrode material, the structural formula of which is shown in Formula I below: , wherein R1 is an aromatic nucleus, at least two of R2, R3, R4 and R5 are acridinium groups / acridine derivative groups, and the rest are hydrogen atoms.

[0008] Preferably, at least two of R2, R3, R4 and R5 are the following groups: , the rest are hydrogen atoms; # indicates the connection position.

[0009] Preferably, the specific structural formula includes the following formulas (I-1) to (I-24):

[0010] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and Any of .

[0011] Preferably, its specific structural formula is 、 、 and Any of .

[0012] In a second aspect, the present application provides a method for preparing a positive electrode material for a lithium-ion battery using the following technical solution:

[0013] A method for preparing a lithium ion battery positive electrode material comprises the following steps: subjecting a halogenated aromatic compound and an acridine / acridine derivative to a coupling reaction to obtain the lithium ion battery positive electrode material.

[0014] Preferably, the method comprises the following steps: mixing acridine / acridine derivatives, halogenated aromatic compounds, solvents and additives for reaction for 10-14 hours under an inert gas atmosphere, and purifying to obtain the lithium-ion battery positive electrode material.

[0015] Preferably, the additive includes one or more of palladium acetate, tri-tert-butylphosphine tetrafluoroborate, potassium tert-butoxide and potassium hydroxide.

[0016] Preferably, when the halogen atom in the halogenated aromatic compound is substituted on a benzene ring, the additive comprises palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide, and the molar ratio of the halogenated aromatic compound, palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide is 1:(0.03-0.09):(0.05-0.12):(4-8); and the purification comprises the following steps: mixing the reacted substance with water, extracting with dichloromethane and concentrating the organic layer, then purifying by silica gel column chromatography and then recrystallizing with dichloromethane and n-hexane.

[0017] Preferably, when the halogen atom in the halogenated aromatic compound is substituted on a benzene ring, the additive comprises palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide, and the molar ratio of the halogenated aromatic compound, palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide is 1:(0.03-0.09):(0.05-0.12):(4-8); the reaction temperature is 105-115° C.; and the purification comprises the following steps: mixing the reacted substance with water, extracting with dichloromethane, concentrating the organic layer, and then purifying by silica gel column chromatography and then recrystallizing with dichloromethane and n-hexane.

[0018] Preferably, when the halogen atom in the halogenated aromatic compound is substituted with an alkyl group, the additive includes potassium hydroxide, and the molar ratio of the halogenated aromatic compound to the potassium hydroxide is 1:8-12; the purification includes the following steps: mixing the reacted substance with water, filtering under reduced pressure to collect the filter residue, purifying it through silica gel column chromatography, and then recrystallizing it with n-hexane.

[0019] Preferably, when the halogen atom in the halogenated aromatic compound is substituted with an alkyl group, the additive includes potassium hydroxide, and the molar ratio of the halogenated aromatic compound to the potassium hydroxide is 1:8-12; the reaction temperature is room temperature; and the purification includes the following steps: mixing the reacted substance with water, filtering under reduced pressure to collect the filter residue, and then purifying it through silica gel column chromatography and then recrystallizing it with n-hexane.

[0020] Preferably, the eluents in the silica gel column chromatography purification process include dichloromethane (DCM) and petroleum ether (PE).

[0021] Preferably, the volume ratio of dichloromethane (DCM) to petroleum ether (PE) is 1:3.5-4.5.

[0022] In a third aspect, the present application provides a positive electrode sheet adopting the following technical solution:

[0023] A positive electrode sheet comprises the lithium ion battery positive electrode material, a conductive agent and a binder.

[0024] Preferably, the conductive agent includes one or more of conductive carbon black, graphene, carbon nanotubes, acetylene black, Ketjen black or ordered mesoporous carbon.

[0025] In a fourth aspect, the present application provides a lithium-ion battery employing the following technical solution:

[0026] A lithium-ion battery comprises the positive electrode sheet, a separator, an electrolyte and a negative electrode sheet.

[0027] In summary, this application includes at least one of the following beneficial technical effects:

[0028] 1. With an aromatic core as the intermediate core and an acridinium / acridine derivative group at the end of the intermediate core as an electropolymerization unit, the intermediate core determines the molecular aggregation state of the lithium-ion battery cathode material, while the acridinium / acridine derivative group determines the molecular chemical structure of the lithium-ion battery cathode material. The combined effect of the two improves the reversible redox ability, electrochemical stability, rate capability, and cycle performance of the lithium-ion battery cathode material as an organic electrode material.

[0029] 2. The lithium-ion battery cathode material of this application exhibits a high discharge voltage exceeding 3.6 V, thereby improving the energy density of the battery;

[0030] 3. When oxidized, nitrogen atoms in the lithium-ion battery cathode material of this application lose electrons to form positively charged cation radicals. These atoms then combine with large anions in the electrolyte to compensate for the charge, thereby improving the rate performance of the lithium-ion battery.

[0031] 4. The electropolymerization behavior of the lithium-ion battery positive electrode material of the present application during the charge and discharge process is beneficial to improving the battery cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a comparison diagram of the aggregation structure of the lithium-ion battery positive electrode materials provided in Example 1 and Example 2 of the present application.

[0033] Figure 2 This is a comparison diagram of the aggregation structure of the lithium-ion battery positive electrode materials provided in Examples 3 and 4 of the present application.

[0034] Figure 3 This is a cycle performance diagram of the lithium-ion battery provided in Example 9 of the present application.

[0035] Figure 4 This is an infrared spectrum of the positive electrode sheet of Example 5 of the present application before and after the lithium-ion battery cycle test provided in Example 9.

[0036] Figure 5 This is a scanning electron microscope image of the positive electrode sheet of Example 5 of the present application before and after the lithium ion battery cycle test provided in Example 9.

[0037] Figure 6 1 is a comparison chart of the rate performance of the lithium-ion batteries provided in Example 9 and Example 10.

[0038] Figure 7 This is a comparison chart of the rate performance of the lithium-ion batteries provided in Example 11 and Example 12.

[0039] Figure 8 This is a rate performance diagram of the lithium-ion battery provided in Example 9 under different activation current rate conditions.

[0040] Figure 9 This is a comparison diagram of the cyclic voltammetry curves of the lithium-ion batteries provided in Examples 9-12.

[0041] Figure 10 It is a comparison diagram of the constant current charge and discharge curves of the lithium ion batteries provided in Examples 9-12. DETAILED DESCRIPTION

[0042] The present application is described in further detail below with reference to the examples. The following examples are intended to illustrate the present invention only and should not be construed as limiting the scope of the present invention. In the following examples, if specific conditions are not specified, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. The methods used are conventional methods well known in the art unless otherwise specified, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise indicated, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention. The raw materials used in the examples and comparative examples can be obtained commercially.

[0043] Example 1

[0044] Example 1 of the present application provides a positive electrode material for a lithium-ion battery, which is prepared by the following method:

[0045] Under nitrogen atmosphere, 1, 4-dibromobenzene (400.0 mg, 1.71 mmol), 9,10-dihydro-9,9-dimethylacridine (715.8 mg, 3.42 mmol), palladium acetate (20.2 mg, 0.09 mmol), tri-tert-butylphosphine tetrafluoroborate (37.7 mg, 0.13 mmol), and potassium tert-butoxide (1151.3 mg, 10.26 mmol) were placed in a Schlenk reaction tube. Toluene (20 mL) was added, and the mixture was heated at reflux at 110 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature, poured into water, extracted three times with dichloromethane, and the organic layer is concentrated to obtain a crude product. The crude product is purified by silica gel column chromatography (eluent: DCM: PE = 1:4) and recrystallized with dichloromethane and n-hexane to obtain a lithium ion battery positive electrode material represented by formula (I-1) (white powder, 520 mg, yield: 62.1%).

[0046] The prepared lithium-ion battery cathode material having a structure as shown in formula (I-1) was characterized by hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum and mass nuclear magnetic resonance spectrum. The characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.61 (s, 4H,ArH), 7.50 (d, J= 7.3 Hz, 4H, ArH), 7.09 (t, J = 7.4 Hz, 4H, ArH), 6.99 (t, J =7.3 Hz, 4H, ArH), 6.45 (d, J = 8.0 Hz, 4H, ArH), 1.72 (s, 12H, -CH3). 13 C NMR (100 MHz, CDCl3) δ (ppm): 140.79, 133.95, 130.35, 126.50, 125.29, 120.90, 113.99, 36.06, 31.03. MS (EI, m / z ): [M] + calcd for: C 36 H 32 N2, 492.67; Found:492.60.

[0047] Example 2

[0048] Example 2 of the present application provides a lithium-ion battery positive electrode material, which is prepared by the following method:

[0049] Under nitrogen atmosphere, 2,7-dibromofluorene (400.0 mg, 1.24 mmol), 9,10-dihydro-9,9-dimethylacridine (571.4 mg, 2.73 mmol), palladium acetate (13.5 mg, 0.06 mmol), tri-tert-butylphosphine tetrafluoroborate (26.1 mg, 0.09 mmol), and potassium tert-butoxide (834.8 mg, 7.44 mmol) were placed in a Schlenk reaction tube. Toluene (20 mL) was added, and the mixture was heated at reflux at 110 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature and poured into water. The mixture is extracted three times with dichloromethane and the organic layer is concentrated to obtain a crude product. The crude product is purified by silica gel column chromatography (eluent: DCM: PE = 1:4) and recrystallized with dichloromethane and n-hexane to obtain a lithium ion battery positive electrode material as shown in formula (I-7) (light yellow powder, 350 mg, yield: 48.7%).

[0050] The prepared lithium-ion battery cathode material having a structure as shown in formula (I-7) was characterized by hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum and mass nuclear magnetic resonance spectrum. The characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.11 (d, J= 7.9Hz, 2H, ArH), 7.56 (s, 2H, ArH), 7.48 (d, J = 7.5 Hz, 4H, ArH), 7.42 (d, J = 7.9Hz, 2H, ArH), 7.01 – 6.90 (m, 8H, ArH), 6.37 (d, J = 7.6 Hz, 4H, ArH), 4.10 (s, 2H, -CH2), 1.72 (s, 12H, -CH3). 13 C NMR (100 MHz, CDCl3) δ (ppm): 146.36,141.06, 140.93, 140.20, 130.25, 130.05, 128.11, 126.37, 125.31, 122.23,120.57, 114.10, 37.12, 36.02, 31.38. MS (EI, m / z ): [M] + calcd for: C 43 H 36 N2,580.78; Found: 580.75.

[0051] Example 3

[0052] Example 3 of the present application provides a lithium-ion battery positive electrode material, which is prepared by the following method:

[0053] Under nitrogen atmosphere, tri(4-bromophenyl)amine (400.0 mg, 0.84 mmol), 9,10-dihydro-9,9-dimethylacridine (544.2 mg, 2.60 mmol), palladium acetate (9.0 mg, 0.04 mmol), tri-tert-butylphosphine tetrafluoroborate (17.4 mg, 0.06 mmol) and potassium tert-butoxide (565.5 mg, 5.04 mmol) were placed in a Schlenk reaction tube, toluene (20 mL) was added, and the mixture was heated at reflux at 110 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature, poured into water, extracted three times with dichloromethane, and the organic layer is concentrated to obtain a crude product. The crude product is purified by silica gel column chromatography (eluent: DCM: PE = 1:4) and recrystallized with dichloromethane and n-hexane to obtain a lithium ion battery positive electrode material represented by formula (I-17) (white powder, 450.0 mg, yield: 61.8%).

[0054] The prepared lithium-ion battery cathode material having a structure as shown in formula (I-17) was characterized by hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum and mass nuclear magnetic resonance spectrum. The characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.53 (d, J = 8.2Hz, 6H, ArH), 7.47 (d, J = 7.7 Hz, 6H, ArH), 7.34 (d, J = 8.2 Hz, 6H, ArH), 7.05(t, J = 7.6 Hz, 6H, ArH), 6.95 (t, J = 7.4 Hz, 6H, ArH), 6.46 (d, J = 8.1 Hz, 6H, ArH), 1.70 (s, 18H, -CH3). 13 C NMR (100 MHz, CDCl3) δ (ppm): 146.97, 141.07,136.19, 132.46, 130.20, 126.43, 126.28, 125.22, 120.66, 114.03, 36.01, 31.08. MS (MALDI-TOF) calcd. for C 63 H 54 N4[M+H] + : 866.43; Found: 866.60.

[0055] Example 4

[0056] Example 4 of the present application provides a lithium-ion battery positive electrode material, which is prepared by the following method:

[0057] 9,10-Dihydro-9,9-dimethylacridine (753.4 mg, 3.60 mmol) and ground potassium hydroxide (504.9 mg, 9.00 mmol) were placed in a round-bottom flask, dissolved in N,N-dimethylformamide (20 mL), and stirred at room temperature for 1 h. 1,2,4,5-Tetrabromomethylbenzene (400.0 mg, 0.90 mmol) was then added in small portions and stirred at room temperature for 12 h. At the end of the reaction, water was added to produce a precipitate. After vacuum filtration, the residue was collected to obtain the crude product. The crude product was purified by silica gel chromatography and recrystallized from dichloromethane and n-hexane to obtain the lithium-ion battery cathode material represented by Formula (I-22) (white powder, 150.0 mg, yield: 17.3%).

[0058] The prepared lithium-ion battery cathode material having a structure as shown in formula (I-22) was characterized by hydrogen nuclear magnetic resonance spectrum, carbon nuclear magnetic resonance spectrum and mass nuclear magnetic resonance spectrum. The characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ (ppm): 7.24 – 7.09 (m,8H, ArH), 6.79 (t, J = 7.4 Hz, 8H, ArH), 6.71 (d, J = 8.5 Hz, 10H, ArH), 6.39 (d, J = 7.6 Hz, 8H, ArH), 5.01 (s, 8H, -CH2), 1.34 (s, 24H, -CH3). 13 C NMR (100 MHz, CDCl3) δ (ppm): 139.84, 132.17, 131.57, 127.27, 126.19, 123.84, 120.42, 112.58, 47.50, 35.81, 28.96. MS (MALDI-TOF) calcd. for C 70 H 66 N4[M+H] + : 963.33;Found: 963.65.

[0059] Example 5

[0060] Example 5 of the present application provides a positive electrode sheet, which is prepared by the following method:

[0061] Weigh 40 mg of the lithium-ion battery positive electrode material prepared in Example 1 and 40 mg of conductive carbon black Super P in a mortar and grind them evenly. Add a mixed solution of polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) at a mass ratio of 4:4:2 of lithium-ion battery positive electrode material, conductive carbon black and polyvinylidene fluoride (PVDF). Transfer the mixed solution to a small beaker, stir and mix at 60 ° C for 1 hour, and then coat it on aluminum foil with a thickness of 120 μm. After vacuum drying at 100 ° C for 12 hours, slice it to obtain a 12 mm diameter and a loading of 0.9-1.2 mg cm -2 The positive electrode.

[0062] Example 6

[0063] Example 6 of the present application provides a positive electrode sheet. The difference between Example 6 and Example 5 is that Example 6 uses the lithium-ion battery positive electrode material prepared in Example 2 to replace the lithium-ion battery positive electrode material prepared in Example 1.

[0064] Example 7

[0065] Example 7 of the present application provides a positive electrode sheet. The difference between Example 7 and Example 5 is that Example 7 uses the lithium-ion battery positive electrode material prepared in Example 3 to replace the lithium-ion battery positive electrode material prepared in Example 1.

[0066] Example 8

[0067] Example 8 of the present application provides a positive electrode sheet. The difference between Example 8 and Example 5 is that Example 8 uses the lithium-ion battery positive electrode material prepared in Example 4 to replace the lithium-ion battery positive electrode material prepared in Example 1.

[0068] Example 9

[0069] Example 9 of the present application provides a lithium ion battery, which is prepared by the following method:

[0070] First, place the negative electrode shell on a workbench. Place the spring, gasket, and negative electrode sheet (lithium sheet) in that order. Add 20 μL of electrolyte to the lithium sheet, place the separator, and again add 20 μL of electrolyte. Place the positive electrode sheet prepared in Example 5, cover with the positive electrode shell, and press-pack the components using a battery packaging machine to obtain a lithium-ion battery (CR2032 button cell). After assembly, let the battery rest for at least 6 hours to ensure that the separator and positive electrode sheet are fully soaked by the electrolyte. The electrolyte used is a solution of 1.0 M lithium hexafluorophosphate (LiPF6) dissolved in ethylene carbonate (EC) and diethyl carbonate (DEC) (v / v = 1 / 1).

[0071] Example 10

[0072] Example 10 of the present application provides a lithium-ion battery. The difference between Example 10 and Example 9 is that Example 10 uses the positive electrode sheet prepared in Example 6 to replace the positive electrode sheet prepared in Example 5.

[0073] Example 11

[0074] Example 11 of the present application provides a lithium-ion battery. The difference between Example 11 and Example 9 is that Example 11 uses the positive electrode sheet prepared in Example 7 to replace the positive electrode sheet prepared in Example 5.

[0075] Example 12

[0076] Example 12 of the present application provides a lithium-ion battery. The difference between Example 12 and Example 9 is that Example 12 uses the positive electrode sheet prepared in Example 8 to replace the positive electrode sheet prepared in Example 5.

[0077] Test and Inspection

[0078] (1) Detect the aggregation structure diagram of the lithium ion battery positive electrode material provided in Examples 1-4, such as Figure 1-2 As shown, Figure 1 (a) is a diagram of the aggregated structure of the lithium-ion battery cathode material provided in Example 1; Figure 1 (b) is a diagram showing the aggregated structure of the lithium-ion battery cathode material provided in Example 2; Figure 2 (a) is a diagram of the aggregated structure of the lithium-ion battery cathode material provided in Example 3; Figure 2 (b) is a diagram of the aggregated structure of the lithium-ion battery positive electrode material provided in Example 4.

[0079] (2) The cycle performance of the lithium-ion battery provided in Example 9 was measured, and the cycle performance graph was obtained as shown in FIG. Figure 3 As shown, the positive electrode sheets in the lithium-ion battery before and after the cycle were detected and the infrared spectra were obtained as shown in Figure 4 As shown in the scanning electron microscope image Figure 5 shown.

[0080] (3) The rate performance of the lithium-ion batteries provided in Examples 9-12 was measured, and the rate performance graph was obtained as shown in FIG. Figure 6-8 As shown, Figure 6 The rate performance diagram of the lithium ion battery provided in Example 9 ( Figure 6 (a)) and the rate performance diagram of the lithium ion battery provided in Example 10 ( Figure 6 The comparison diagram of (b) is shown in the figure below, where Figure 7 The rate performance diagram of the lithium ion battery provided in Example 11 ( Figure 7 (a)) and the rate performance diagram of the lithium ion battery provided in Example 12 ( Figure 7 The comparison chart of (b) is as follows: Figure 8 This is a rate performance diagram of the lithium-ion battery provided in Example 9 under different activation current rate conditions.

[0081] (4) Measure the cyclic voltammetry curves of the lithium ion batteries provided in Examples 9-12, as shown in FIG. Figure 9 As shown, Figure 9 (a) is a cyclic voltammetry curve of the lithium ion battery provided in Example 9; Figure 9 (b) is a cyclic voltammetry graph of a lithium-ion battery provided in Example 10; Figure 9 (c) is a cyclic voltammetry curve of the lithium ion battery provided in Example 11; Figure 9 (d) is a cyclic voltammetry curve of the lithium-ion battery provided in Example 12.

[0082] (5) Determine the constant current charge and discharge curves of the lithium ion batteries provided in Examples 9-12, as shown in FIG. Figure 10 As shown, Figure 10(a) is a constant current charge and discharge curve diagram of the lithium ion battery provided in Example 9; Figure 10 (b) is a constant current charge and discharge curve diagram of the lithium-ion battery provided in Example 10; Figure 10 (c) is a constant current charge and discharge curve diagram of the lithium ion battery provided in Example 11; Figure 10 (d) is a constant current charge and discharge curve diagram of the lithium-ion battery provided in Example 12.

[0083] Result Analysis

[0084] The following combination Figure 1-10 The experimental data provided are used to explain this application in detail.

[0085] Reference Figure 1 and Figure 6 The lithium ion battery provided in Example 9 has a better rate performance than the lithium ion battery provided in Example 10, and the specific capacity of the lithium ion battery provided in Example 9 decreases less at 20C. Figure 1 Analysis shows that in the aggregation structure diagram of the lithium-ion battery positive electrode material used in the lithium-ion battery provided in Example 9 and Example 10, the lithium-ion battery positive electrode material used in the lithium-ion battery provided in Example 9 has a closer polymerization site and a more planar polymerization mode than the lithium-ion battery positive electrode material used in the lithium-ion battery provided in Example 10, indicating that the intermediate core of the lithium-ion battery positive electrode material in Example 1 is beneficial to improving the rate performance of the prepared lithium-ion battery by changing the aggregation structure. And referring to Figure 8 The lithium-ion battery provided in Example 9 can still operate normally at a high rate of 100C, indicating that the material has excellent rate performance.

[0086] Reference Figure 2 and Figure 7 The rate performance of the lithium-ion battery provided in Example 11 is better than that of the lithium-ion battery provided in Example 12, and the rate performance of the lithium-ion batteries provided in Examples 11 and 12 is improved when the activation current rate is increased to 5C. Figure 2 Analysis shows that in the aggregation structure diagram of the lithium ion battery positive electrode material used in the lithium ion batteries provided in Examples 11 and 12, the lithium ion battery positive electrode material used in the lithium ion battery provided in Example 11 has larger channels for ion transmission than the lithium ion battery positive electrode material used in the lithium ion battery provided in Example 12, indicating that the intermediate core of the lithium ion battery positive electrode material of Example 3 is beneficial to improving the rate performance of the prepared lithium ion battery by changing the aggregation structure.

[0087] Reference Figure 3 The lithium-ion battery provided in Example 9 can still maintain 62.8 mAhg after 20,000 cycles at 50C.-1 The reversible capacity, capacity retention rate is 77.3%, the average capacity decay rate per cycle is 0.0011%, and the coulombic efficiency is stable at 100%, showing excellent cycle performance. Figure 4 The infrared spectrum of the cathode prepared in Example 5 shows that the positive electrode sheet after the cycle is at a wave number of 700-750 cm -1 The bending vibration peak of the ortho-disubstituted CH of the benzene ring disappears and is located at the wave number 800-820 cm -1 The 1, 2, 4-trisubstituted vibration peak of the benzene ring at 100 nm appears, proving that the acridine group undergoes CC coupling polymerization during the battery cycle. Figure 5 It can be seen from the scanning electron micrograph that the surface of the positive electrode sheet prepared in Example 5 is uniform and dense before the cycle, and particles of 100-300 nm in size appear on the surface after the cycle, indicating that as the cycle proceeds, the surface of the positive electrode sheet prepared in Example 5 forms a larger surface structure that is more conducive to electrode liquid infiltration and anion shuttling, which is beneficial to improving the cycle performance of the lithium-ion battery.

[0088] Reference Figure 9 As can be seen from the figure, the disappearance of the oxidation peak that appeared in the first forward scan indicates the occurrence of in situ electropolymerization of the acridine group. The symmetry and reversibility of the scanning curve after the 5th cycle indicate that the polymerized material has excellent reversible redox ability and electrochemical stability.

[0089] Reference Figure 10 As can be seen from the figure, the lithium-ion batteries of Examples 9-12 all exhibited a discharge voltage exceeding 3.6 V and a relatively high specific capacity, which is beneficial to the improvement of energy density; and the specific capacity and voltage of the lithium-ion battery positive electrodes of Examples 9, 10 and 12 gradually increased with the progress of the cycle, indicating a process of electropolymerization activation, indicating that the lithium-ion battery positive electrode materials prepared by Examples 1-4 are beneficial to improving the discharge voltage, specific capacity and energy density of the lithium-ion battery.

Claims

1. Application of a lithium-ion battery positive electrode material in preparing a lithium-ion battery positive electrode, characterized in that: The specific structural formula of the lithium-ion battery positive electrode material is: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and Any of .

2. A method for preparing a lithium-ion battery positive electrode material according to claim 1, characterized in that: The following steps are involved: Under an inert gas atmosphere, an acridine derivative, a halogenated aromatic compound, a solvent and an additive are mixed and reacted for 10-14 hours, and purified to obtain a lithium-ion battery positive electrode material with structural formula (I-1) to (I-24) as described in claim 1; the additive is one or more of palladium acetate, tri-tert-butylphosphine tetrafluoroborate, potassium tert-butoxide and potassium hydroxide.

3. The method for preparing a positive electrode material for a lithium ion battery according to claim 2, wherein: When the halogen atom in the halogenated aromatic compound is substituted on a benzene ring, the additive is palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide, and the molar ratio of the halogenated aromatic compound, palladium acetate, tri-tert-butylphosphine tetrafluoroborate and potassium tert-butoxide is 1:(0.03-0.09):(0.05-0.12):(4-8); The purification comprises the following steps: mixing the reacted substance with water, extracting with dichloromethane and concentrating the organic layer, purifying with silica gel column chromatography and then recrystallizing with dichloromethane and n-hexane.

4. The method for preparing a positive electrode material for a lithium ion battery according to claim 2, wherein: When the halogen atom in the halogenated aromatic compound is substituted on an alkyl group, the additive is potassium hydroxide, and the molar ratio of the halogenated aromatic compound to the potassium hydroxide is 1:8-12; The purification comprises the following steps: mixing the reacted substance with water, collecting the filter residue by vacuum filtration, purifying the residue by silica gel column chromatography, and then recrystallizing the residue by using n-hexane.

5. A positive electrode sheet, characterized in that: The invention comprises a lithium-ion battery positive electrode material having the structural formula (I-1) to (I-24) as described in claim 1, a conductive agent and a binder.

6. A lithium-ion battery, characterized in that: The invention comprises the positive electrode sheet, the separator, the electrolyte and the negative electrode sheet as claimed in claim 5.

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