Doping modified ternary positive electrode material, preparation method thereof and battery

Abstract

The invention discloses a doped modified ternary positive electrode material, a preparation method thereof and a battery, and belongs to the technical field of batteries and ternary materials. The preparation method comprises the following steps: respectively weighing Ni0. 8Co0. 1Mn0. 1 (OH) 2, lithium hydroxide and a doping agent according to a molar ratio, mixing and grinding to form a mixture; and calcining the mixture in sections in an oxygen atmosphere, grinding and sieving to obtain the doped and modified ternary positive electrode material. The high-nickel ternary material is doped with a proper amount of Ti and V, and the Ti and V have a synergistic effect, so that the stability of the material structure is improved, the cation mixing degree is reduced, the reversible degree of the material and the reaction kinetics are improved, and the electrochemical performance of the material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries and ternary materials, and more specifically, the application relates to a doped modified ternary positive electrode material, a preparation method thereof and a battery. BACKGROUND

[0002] Due to the non-renewable nature of fossil energy and the resulting environmental problems, the combined use of green renewable energy (such as solar energy, wind energy, tidal energy, nuclear energy, etc.) has become an international trend. However, mechanical, chemical and thermal energy storage with low energy conversion efficiency easily leads to waste of energy transmission and increasingly cannot meet the needs of today's society. As a high-energy conversion efficiency energy storage system, electrochemical energy storage has attracted the attention of many scholars and experts. In the 20th century, the technology of electrical energy storage developed rapidly, and the initial battery technology also emerged. However, with the development of society, it has become increasingly difficult to meet the needs in terms of energy storage density, cycle life, price and environmental protection. Lithium-ion batteries have a comprehensive and significant advantage in terms of energy storage density, cycle life, price and environmental protection, and have gradually become the mainstream of today's electrochemical energy storage system.

[0003] High-nickel ternary positive electrode materials (such as NCM811) used in lithium-ion batteries have high specific capacity and can achieve high energy density, effectively reducing battery costs. However, high-nickel materials also have poor cycle stability and thermal stability. A large number of studies have shown that different synthesis methods have a significant impact on the microstructure and interface characteristics of NCM811 positive electrode materials, and the microstructure and interface characteristics of NCM811 positive electrode materials are gradually becoming the development trend of high-nickel positive electrode materials. The sol-gel method and the hydrothermal method have more potential and advantages in the design of nanostructures of positive electrode materials, but the problem of cycle stability must be solved. The spray drying method has great advantages in the processing and synthesis of positive electrode materials, but the structural defects caused in the synthesis limit its widespread application. The high-temperature solid-phase method has a mature process operation and is suitable for widespread application and development. These synthesis methods of NCM811 can effectively improve the electrochemical performance of NCM811, thereby improving its application value.

[0004] Although the high-temperature solid-phase method can well control the cost and be suitable for industrial production, this process can cause the following problems: low tap density, cation mixing, irreversible phase transition, and loss of active lithium due to side reactions, thereby affecting the electrochemical performance. Therefore, it is of great significance to study how to improve the electrochemical performance of high-nickel ternary positive electrode materials. SUMMARY

[0005] An object of the present application is to solve at least the problems and / or drawbacks described above, and to provide at least the advantages stated below.

[0006] To achieve these objects and other advantages of the present application, a method for preparing a doped modified ternary positive electrode material is provided, characterized in that it comprises the following steps: Step one, mixing Ni 0.8 Co 0.1 Mn 0.1 (OH)2, lithium hydroxide and a dopant, and grinding to form a mixture; Step two, calcining the mixture in an oxygen atmosphere in sections, grinding and sieving to obtain a doped modified ternary positive electrode material.

[0007] Preferably, in the step one, the molar ratio of Ni 0.8 Co 0.1 Mn 0.1 (OH)2and lithium hydroxide is 1:1.03~1.07.

[0008] Preferably, in the step one, the dopant is one or both of titanium dioxide and vanadium pentoxide; wherein the molar ratio of the titanium dioxide to the Ni 0.8 Co 0.1 Mn 0.1 (OH)2is 0.001~0.005:1; and the molar ratio of the vanadium pentoxide to the Ni 0.8 Co 0.1 Mn 0.1 (OH)2is 0.001~0.005:1.

[0009] Preferably, in the step two, the specific steps of calcining in sections are as follows: heating at a certain heating rate to 100~200℃ and keeping for 0.2~1 h, heating to 450~550℃ and keeping for 3~7 h, heating to 800~900℃ and keeping for 3~7 h, then cooling at a certain cooling rate to 750~800℃ and keeping for 8~12 h, and finally cooling to 100~200℃.

[0010] Preferably, the heating rate is 2~4℃ / min, and the cooling rate is 1~3℃ / min.

[0011] Preferably, in the step two, the grinding is through a 400~600 mesh sieve.

[0012] Preferably, the dopant is titanium dioxide and vanadium pentoxide.

[0013] Preferably, before adding the titanium dioxide and vanadium pentoxide, the titanium dioxide and vanadium pentoxide are subjected to a modification treatment, comprising the following steps: S11, TiO2 and V2O5 are mixed in a molar ratio of 1-5:1-5, then added into deionized water, stirred uniformly, then polyethylene glycol 400 is added, stirred uniformly, to obtain a dispersion liquid; S12, acrylamide and ammonium persulfate are added into the dispersion liquid, reacted at 60-90 DEG C for 4-8h, suction filtered, washed with anhydrous ethanol, vacuum dried, to obtain product A; S13, silane coupling agent is added into anhydrous ethanol, to prepare a silane coupling agent solution with a concentration of 1-10wt%, product A and the silane coupling agent solution are mixed, heated to 60-80 DEG C, stirred for 1-3h, suction filtered, washed with anhydrous ethanol, deionized water in sequence, vacuum dried, to obtain modified TiO2 and V2O5.

[0014] Preferably, in S11, the mass ratio of the total mass of TiO2 and V2O5, deionized water and polyethylene glycol 400 is 1:10-50:0.1-0.3.

[0015] Preferably, in S12, the mass ratio of the total mass of TiO2 and V2O5 to acrylamide is 1:0.1-2; the mass ratio of acrylamide to ammonium persulfate is 5-20:0.1.

[0016] Preferably, in S13, the mass ratio of product A to the silane coupling agent solution is 1:3-8.

[0017] A doped and modified ternary positive electrode material is prepared by the preparation method of the doped and modified ternary positive electrode material.

[0018] A battery, wherein the positive electrode material of the battery is the doped and modified ternary positive electrode material.

[0019] The present application at least includes the following beneficial effects: the present application dopes appropriate amounts of Ti and V in high-nickel ternary materials, both of which improve the stability of the material structure through synergistic effect, reduce the degree of cation mixing, improve the degree of reversibility and the kinetics of the reaction, and improve the electrochemical performance of the material. In addition, the present application also includes modification treatment of TiO2 and V2O5, so that TiO2 and V2O5 have good dispersibility and stability, so that Ti and V can be uniformly doped into the crystal lattice of NCM, so that the structure is more stable; wherein, a dispersant polyethylene glycol is first added to prepare a dispersion liquid, then a initiator ammonium persulfate and acrylamide are used to form polyacrylamide on the surface of TiO2 and V2O5, so as to improve the dispersibility and interface reactivity, which is beneficial to subsequent reaction, and carbon and nitrogen elements are introduced, which can further improve the conductivity of the material, and finally silane coupling agent is added to further improve the dispersibility and stability.

[0020] Additional advantages, objects, and features of the application will be apparent from the following description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 XRD patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application; Figure 2 SEM images of NCM-0.32 prepared for Example 1 of the present application and NCM-1.05 prepared for Comparative Example 1 at different magnifications (5K, 1W, 2W), wherein A is NCM-1.05 and B is NCM-0.32; 1 is 2W, 2 is 1W and 3 is 5K; Figure 3 0.1C first charge-discharge curve patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application; Figure 4 Cycle performance patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application at 1C; Figure 5 Rate performance patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application; Figure 6 Cyclic voltammetry patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application; Figure 7 Impedance patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application before cycling; Figure 8 Impedance patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared for Examples 1-3 of the present application after cycling; Figure 9 Rate performance patterns of NCM-0.32 prepared for Example 1 of the present application and NCM-1.05 prepared for Comparative Example 1. DETAILED DESCRIPTION

[0022] The present application will now be described in further detail by way of reference only to the accompanying drawings, where:

[0023] It should be understood that the terms such as "have", "have", and "include" used herein do not exclude the presence or addition of one or more other elements.

[0024] Example 1 A preparation method of a doped modified ternary positive electrode material, comprising the following steps: Step one, 92.3g of Ni 0.8 Co 0.1 Mn 0.1 (OH)2, 44.1g of LiOH·H2O and 0.32g of TiO2 are mixed and fully ground for 2h to form a mixture; Step two, the mixture is placed in a muffle furnace and calcined in stages in an oxygen atmosphere, the temperature is raised to 150℃ and kept for 0.5h, the temperature is raised to 500℃ and kept for 5h, the temperature is raised to 850℃ and kept for 5h, the temperature is lowered to 780℃ and kept for 10h, and finally the temperature is lowered to 150℃, the material is taken out, ground and filtered with a 500 mesh screen to obtain a doped modified ternary positive electrode material NCM-0.32; wherein the temperature raising rate is 3℃ / min and the temperature lowering rate is 2℃ / min.

[0025] Example 2 In this example, the amount of TiO2 is 0.24g (0.003mol), and the remaining steps are the same as in Example 1 to obtain a doped modified ternary positive electrode material NCM-0.24.

[0026] Example 3 In this example, the amount of TiO2 is 0.40g (0.005mol), and the remaining steps are the same as in Example 1 to obtain a doped modified ternary positive electrode material NCM-0.40.

[0027] Example 4 In this example, 0.004mol of V2O5 (0.73g) is used instead of TiO2, and the remaining steps are the same as in Example 1 to obtain a doped modified ternary positive electrode material NCM-0.73.

[0028] Example 5 A preparation method of a doped modified ternary positive electrode material, comprising the following steps: Step one, 92.3g of Ni 0.8 Co 0.1 Mn 0.1 (OH)2, 44.1g of LiOH·H2O and 0.32g of TiO2 and 0.73g of V2O5 are mixed and fully ground for 2h to form a mixture; Step two, the mixture is placed in a muffle furnace, calcined in stages in an oxygen atmosphere, the temperature is raised to 150°C and kept for 0.5h, the temperature is raised to 500°C and kept for 5h, the temperature is raised to 850°C and kept for 5h, the temperature is lowered to 780°C and kept for 10h, and finally the temperature is lowered to 150°C, the material is taken out after grinding and filtering with a 500 mesh screen, and a doped modified ternary positive electrode material NCM-Ti-V is obtained; wherein the heating rate is 3°C / min and the cooling rate is 2°C / min; In this embodiment, TiO2 and V2O5 are doped, and the remaining steps are the same as in Example 1.

[0029] Example 6 In this embodiment, TiO2 and V2O5 are modified before being added, and modified TiO2 and V2O5 are obtained, i.e., modified TiO2 and V2O5 are used to replace TiO2 and V2O5, and the remaining steps are the same as in Example 5, to obtain a doped modified ternary positive electrode material NCM-1; wherein the specific method for modifying TiO2 and V2O5 includes the following steps: S11, mix TiO2 and V2O5 in a molar ratio of 1:1, then add deionized water, stir until uniform, then add polyethylene glycol 400, stir until uniform, and obtain a dispersion; the mass ratio of the total mass of TiO2 and V2O5 to the mass of deionized water and polyethylene glycol 400 is 1:20:0.2; S12, add acrylamide and ammonium persulfate to the dispersion, react at 80°C for 6h, filter, wash with anhydrous ethanol 3 times, and vacuum dry to obtain product A; wherein the mass ratio of the total mass of TiO2 and V2O5 to the mass of acrylamide is 1:0.5; the mass ratio of acrylamide to ammonium persulfate is 10:0.1; S13, add silane coupling agent KH550 to anhydrous ethanol to prepare a silane coupling agent solution with a concentration of 5wt%, mix product A and the silane coupling agent solution in a mass ratio of 1:5, heat to 70°C and stir for 2h, filter, wash with anhydrous ethanol and deionized water 3 times in turn, and vacuum dry to obtain modified TiO2 and V2O5.

[0030] Example 7 In this embodiment, TiO2 and V2O5 are modified before being added, and modified TiO2 and V2O5 are obtained, i.e., modified TiO2 and V2O5 are used to replace TiO2 and V2O5, and the remaining steps are the same as in Example 5, to obtain a doped modified ternary positive electrode material NCM-2; wherein the specific method for modifying TiO2 and V2O5 includes the following steps: S11, TiO2 and V2O5 were mixed in a molar ratio of 1:1 and then added to deionized water, stirred uniformly, then polyethylene glycol 400 was added and stirred uniformly, filtered, washed with anhydrous ethanol three times, and vacuum dried to obtain product A; the mass ratio of the total mass of TiO2 and V2O5, deionized water, and polyethylene glycol 400 was 1:20:0.2; S12, silane coupling agent KH550 was added to anhydrous ethanol to prepare a silane coupling agent solution with a concentration of 5wt%, product A and the silane coupling agent solution were mixed in a mass ratio of 1:5, heated to 70°C and stirred for 2h, filtered, washed with anhydrous ethanol and deionized water three times in turn, and vacuum dried to obtain modified TiO2 and V2O5; Compared with Example 6, this example does not perform polyacrylamide treatment.

[0031] Example 8 In this example, TiO2 and V2O5 were modified before being added, to obtain modified TiO2 and V2O5, that is, modified TiO2 and V2O5 were used to replace TiO2 and V2O5, and the remaining steps were the same as those of Example 5, to obtain a doped and modified ternary positive electrode material NCM-3; wherein the specific method for modifying TiO2 and V2O5 included the following steps: S11, TiO2 and V2O5 were mixed in a molar ratio of 1:1 and then added to deionized water, stirred uniformly, then polyethylene glycol 400 was added and stirred uniformly, filtered, washed with anhydrous ethanol three times, and vacuum dried to obtain product A; the mass ratio of the total mass of TiO2 and V2O5, deionized water, and polyethylene glycol 400 was 1:20:0.2; S12, acrylamide and ammonium persulfate were added to the dispersion, reacted at 80°C for 6h, filtered, washed with anhydrous ethanol three times, and vacuum dried to obtain modified TiO2 and V2O5; wherein the mass ratio of the total mass of TiO2 and V2O5 to acrylamide was 1:0.5; the mass ratio of acrylamide to ammonium persulfate was 10:0.1; Compared with Example 6, this example does not perform silane coupling agent treatment.

[0032] Example 9 In this example, TiO2 and V2O5 were modified before being added, to obtain modified TiO2 and V2O5, that is, modified TiO2 and V2O5 were used to replace TiO2 and V2O5, and the remaining steps were the same as those of Example 5, to obtain a doped and modified ternary positive electrode material NCM-4; wherein the specific method for modifying TiO2 and V2O5 included the following steps: S11, TiO2 and V2O5 were mixed in a molar ratio of 1:1 and then added to deionized water, stirred uniformly, then polyethylene glycol 400 was added and stirred uniformly, filtered, washed with anhydrous ethanol three times, and vacuum dried to obtain product A; the mass ratio of the total mass of TiO2 and V2O5, deionized water, and polyethylene glycol 400 was 1:20:0.2; S12, acrylamide and ammonium persulfate were added to the dispersion, and reacted at 80°C for 6h, and then filtered, washed with anhydrous ethanol for 3 times, and dried in vacuum to obtain product A; wherein, the mass ratio of total mass of TiO2 and V2O5 to the mass of acrylamide was 1:0.5; the mass ratio of acrylamide to ammonium persulfate was 10:0.1; S13, silane coupling agent KH550 was added to anhydrous ethanol to prepare a silane coupling agent solution with a concentration of 5wt%, product A and the silane coupling agent solution were mixed according to a mass ratio of 1:5, and then heated to 70°C and stirred for 2h, and then filtered, washed with anhydrous ethanol and deionized water for 3 times, and dried in vacuum to obtain modified TiO2 and V2O5. Compared with Example 6, polyethylene glycol 400 is not used in this example.

[0033] Comparative Example 1 A preparation method of a ternary positive electrode material, comprising the following steps: Step one, 92.3g of Ni 0.8 Co 0.1 Mn 0.1 (OH)2 and 44.1g of LiOH·H2O were weighed according to a molar ratio of 1:1.05, and then ground for 2h to form a mixture; Step two, the mixture was placed in a muffle furnace and calcined in stages in an oxygen atmosphere, and then heated to 150°C and kept for 0.5h, heated to 500°C and kept for 5h, heated to 850°C and kept for 5h, cooled to 780°C and kept for 10h, and finally cooled to 150°C, and then the material was taken out, ground and filtered with a 500 mesh sieve to obtain a ternary positive electrode material NCM-1.05; wherein, the heating rate was 3°C / min, and the cooling rate was 2°C / min; In this comparative example, titanium dioxide was not doped, and the remaining steps were the same as those in Example 1.

[0034] Figure 1 The XRD patterns of NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Examples 1-3 were obtained, and it could be found from the figure that NCM-0.24, NCM-0.32 and NCM-0.40 were relatively consistent compared with the standard card of PDF#09-0063, and it could be seen that with the increase of Ti 4+ , the intensity of the peak decreased.

[0035] Figure 2SEM images of NCM-0.32 prepared in Example 1, NCM-1.05 prepared in Comparative Example 1 at different magnifications (5K, 1W, 2W), wherein A1-A3 are NCM-1.05, B1-B3 are NCM-0.32, A1, B1 are 2W magnification, A2, B2 are 1W magnification, A3, B3 are 5K magnification. It can be seen that after doping titanium, the particle size is more uniform, the agglomeration is weakened, and the surface is smoother. For the change of material structure, it is shown that titanium dioxide is effectively doped into the material and changes the surface state of the material, which weakens the agglomeration tendency of the material, significantly improves the morphology and particle size of the material, and increases the resistance of ion movement in the material.

[0036] Electrochemical performance test: (1) Cyclic voltammetry test (CV) The principle of cyclic voltammetry (CV) is to apply a linear scanning voltage from the starting voltage, change the potential direction after reaching the end potential, and record the current change with the electrode potential at the same time, which is used to explore the chemical reaction and reversibility of the electrode material. In this experiment, CHI660D of Shanghai Chenhua Instrument Co., Ltd. was used, the voltage range was set to 2.7-4.3 V, and the scanning rate was 0.2 mV / s.

[0037] (2) Alternating current impedance test (EIS) Electrochemical impedance spectroscopy (EIS) is a test method that uses a small alternating current to disturb the electrode to study the change of interface resistance. The electrochemical workstation used in this experiment is CHI660E, the test frequency range is 0.01~100kH, and the amplitude is 5 mV.

[0038] (3) Battery assembly First, 0.8 grams of positive electrode material, 0.1 grams of acetylene black and 0.1 grams of PVDF were placed in a glass bottle, 1000 microliters of NMP were added to the glass bottle, and stirring was carried out for 12 hours to obtain an electrode slurry; the prepared electrode slurry was uniformly coated on a 12 cm aluminum sheet using a coating machine, and the aluminum sheet with the electrode slurry was placed in a vacuum oven and vacuum dried for 6 h to obtain a positive electrode sheet; a metal lithium sheet was used as the negative electrode; the separator was an imported polypropylene microporous membrane (Celgard 2400); the electrolyte was an equal amount of 1 mol / L LiPF6, ethylene carbonate (EC) and dimethyl carbonate (DMC) mixed solution, and the battery was assembled in an argon glove box, and the model was CR2032.

[0039] Figure 3The NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Examples 1-3 were subjected to first charge-discharge curve mapping at 0.1C, and the data are shown in Table 1. It can be seen that appropriate titanium doping can improve the physical properties and electrochemical properties of the electrode material, and it is possible that Ti 4+ The interlayer spacing of the material is expanded, but excessive doping may affect the stability of the material structure, resulting in reduced coulombic efficiency and specific discharge capacity.

[0040] Table 1 Figure 4 The cycle performance of NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Examples 1-3 at 1C is shown in Table 2. It can be seen that appropriate Ti 4+ doping enhances the M-O bond, improves the stability of the material structure, and thus improves the cycle performance of the material, and the cycle performance of NCM-0.32 is the most excellent; Ti 4+ Excessive doping reduces the stability between materials and reduces the cycle performance of the material.

[0041] Table 2 Figure 5 The rate performance of NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Examples 1-3 is shown in Table 3, which is the specific discharge capacity at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and the specific discharge capacity after returning to 0.1C. It can be seen that the specific discharge capacity of the three materials at 5C rate is 100.61, 152.22, 132.99 m Ah / g, and the specific discharge capacity of NCM-0.32 is better. The material structure of NCM-0.32 is more stable than NCM-0.24 and NCM-0.40 at high rate, indicating that appropriate titanium can improve the stability of the material structure.

[0042] Table 3 Figure 6The cyclic voltammograms of NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Example 1-3, the potential difference of NCM-0.24 is 0.7044 V, the potential difference of NCM-0.32 is 0.415 V, and the potential difference of NCM-0.40 is 0.434 V. It can be seen that the potential difference of NCM-0.24 and NCM-0.40 is greater than that of NCM-0.32, indicating that the degree of electrochemical polarization of NCM-0.32 is better. But the peak symmetry degree of NCM-0.32 is greater than that of NCM-0.24 and less than that of NCM-0.40. It shows that with the increase of titanium doping amount, the reversibility of redox reaction and the kinetics of reaction will also increase.

[0043] Figures 7-8 The impedance diagrams of NCM-0.24, NCM-0.32 and NCM-0.40 prepared in Example 1-3, Figure 7 Before cycling, Figure 8 After cycling. It can be seen that the radius of NCM-0.32 is the smallest, and the charge transfer impedance is the smallest, indicating that the battery prepared by the sample material of NCM-0.32 has lower charge transfer resistance and better electrochemical performance than the battery prepared by the sample material of NCM-0.24 or NCM-0.40.

[0044] The first charge-discharge data of NCM-0.32 prepared in Example 1 and NCM-1.05 prepared in Comparative Example 1 at 0.1C are shown in Table 4. It can be seen that the doping of titanium expands the interlayer spacing between materials, and the doping improves the coulombic efficiency of the material.

[0045] Table 4 The cycle performance data of NCM-0.32 prepared in Example 1 and NCM-1.05 prepared in Comparative Example 1 at 1C are shown in Table 5. It can be seen that the doping of Ti 4+ improves the stability of the material structure, thereby improving the cycle performance of the material.

[0046] Table 5 Figure 9 The rate performance diagram of NCM-0.32 prepared in Example 1 and NCM-1.05 prepared in Comparative Example 1 is shown in Table 6, and the data is the discharge specific capacity at 0.1C, 0.2C, 0.5C, 1C, 2C and 5C, and the discharge specific capacity after returning to 0.1C. It can be seen that the structure of the undoped material has collapsed at 5C, reducing the discharge specific capacity of the material, and Ti 4+The doping of the material can enhance the stability of the ternary positive electrode material at a large rate, and improve the rate performance of the material.

[0047] Table 6 The first charge-discharge data of the doped modified ternary positive electrode material prepared in examples 1, 4-9 at 0.1C are shown in Table 7.

[0048] Table 7 The cycle performance data of the doped modified ternary positive electrode material prepared in examples 1, 4-9 at 1C are shown in Table 8.

[0049] Table 8 The rate performance data of the doped modified ternary positive electrode material prepared in examples 1, 4-9 are shown in Table 9, specifically the discharge specific capacity at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and the discharge specific capacity finally returned to 0.1C.

[0050] Table 9 As can be seen from the above, the present application dopes appropriate amounts of Ti and V in the high-nickel ternary material, which have a synergistic effect and can improve the electrochemical performance of the material, and the electrochemical performance of NCM-Ti-V prepared in example 5 is better than that of example 1 (NCM-0.32) and example 4 (NCM-0.73). The present application can further improve the electrochemical performance of the material by modifying TiO2 and V2O5, and the Coulomb efficiency, cycle performance and rate performance of NCM-1 of example 6 are all optimal.

[0051] Although the embodiments of the present application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method for preparing a doped and modified ternary cathode material, characterized in that, Includes the following steps: Step 1: Ni 0.8 Co 0.1 Mn 0.1 (OH)2, lithium hydroxide, and dopants are mixed and ground to form a mixture; Step 2: The mixture is calcined in stages in an oxygen atmosphere, ground and sieved to obtain the doped and modified ternary cathode material.

2. The method for preparing a doped and modified ternary cathode material as described in claim 1, characterized in that, In step one, Ni 0.8 Co 0.1 Mn 0.1 The molar ratio of (OH)2 to lithium hydroxide is 1:1.03~1.

07.

3. The method for preparing a doped and modified ternary cathode material as described in claim 1, characterized in that, In step one, the dopant is one or both of titanium dioxide and vanadium pentoxide; wherein, the titanium dioxide and the Ni 0.8 Co 0.1 Mn 0.1 The molar ratio of (OH)₂ is 0.001~0.005:1; the vanadium pentoxide and the Ni 0.8 Co 0.1 Mn 0.1 The molar ratio of (OH)2 is 0.001~0.005:

1.

4. The method for preparing a doped and modified ternary cathode material as described in claim 1, characterized in that, In step two, the specific steps of segmented calcination are as follows: at a certain heating rate, the temperature is raised to 100~200℃ and held for 0.2~1 h, then raised to 450~550℃ and held for 3~7 h, then raised to 800~900℃ and held for 3~7 h, then lowered to 750~800℃ at a certain cooling rate and held for 8~12 h, and finally lowered to 100~200℃.

5. The method for preparing a doped and modified ternary cathode material as described in claim 4, characterized in that, The heating rate is 2~4℃ / min, and the cooling rate is 1~3℃ / min.

6. The method for preparing a doped and modified ternary cathode material as described in claim 3, characterized in that, Before adding titanium dioxide and vanadium pentoxide, the titanium dioxide and vanadium pentoxide are modified, including the following steps: S11. Mix TiO2 and V2O5 in a molar ratio of 1~5:1~5, add to deionized water, stir evenly, then add polyethylene glycol 400, stir evenly to obtain a dispersion. S12. Add acrylamide and ammonium persulfate to the dispersion, react at 60~90℃ for 4~8h, filter, wash with anhydrous ethanol, and dry under vacuum to obtain product A; S13. Add the silane coupling agent to anhydrous ethanol to prepare a silane coupling agent solution with a concentration of 1~10wt%. Mix product A with the silane coupling agent solution, heat to 60~80℃ and stir for 1~3h. Filter, wash with anhydrous ethanol and deionized water in sequence, and dry under vacuum to obtain modified TiO2 and V2O5.

7. The method for preparing a doped and modified ternary cathode material as described in claim 6, characterized in that, In S11, the mass ratio of the total mass of TiO2 and V2O5, the mass of deionized water, and the mass of polyethylene glycol 400 is 1:10~50:0.1~0.

3.

8. The method for preparing a doped and modified ternary cathode material as described in claim 6, characterized in that, In S12, the total mass ratio of TiO2 and V2O5 to acrylamide is 1:0.1~2; the mass ratio of acrylamide to ammonium persulfate is 5~20:0.

1. In S13, the mass ratio of product A to silane coupling agent solution is 1:3~8.

9. A doped and modified ternary cathode material, characterized in that, It is prepared by the preparation method of the doped and modified ternary cathode material according to any one of claims 1-8.

10. A battery, characterized in that, The positive electrode material of the battery is the doped and modified ternary positive electrode material as described in claim 9.

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