Cathode materials, methods for preparing cathode materials, and electrochemical devices

Abstract

This application discloses a cathode material, a method for preparing the cathode material, and an electrochemical device. The preparation method includes the following steps: preparing a precursor solution comprising nickel salt, cobalt salt, manganese salt, and titanium salt; performing a co-precipitation reaction on the precursor solution to obtain a cathode material precursor, wherein the mass percentage of titanium element is 0.05% to 0.2% based on the total mass of each metal element in the cathode material precursor; mixing the cathode material precursor with lithium salt to obtain a first mixture; sintering the first mixture once to obtain a first-sintered material; mixing the first-sintered material with zirconium oxide to obtain a second mixture, wherein the mass percentage of zirconium element is 0.05% to 0.2% based on the total mass of the first-sintered material; and sintering the second mixture a second time to prepare the cathode material.

Description

Technical Field

[0001] This application relates to the field of electrochemistry, and more particularly to a cathode material, a method for preparing the cathode material, and an electrochemical device. Background Technology

[0002] Lithium-ion batteries are a new type of green energy storage device. Among them, nickel-cobalt-manganese ternary cathode materials are widely used because of their high energy density, low cost and reliable safety. However, high-nickel and low-cobalt ternary cathode materials have poor cycle stability under high pressure.

[0003] Currently, conventional solutions to the aforementioned technical problems include washing, coating, and doping. However, washing damages the chemical structure of the cathode material surface, affecting battery cycle life. While coating can isolate the cathode material from the electrolyte, its preparation process is complex and cannot meet the needs of large-scale production. Doping suffers from uneven distribution of dopant elements and difficulty in completely washing away residual organic matter. Therefore, a new method for preparing ternary cathode materials is urgently needed to improve the poor cycle stability of existing ternary cathode materials under high voltage. Summary of the Invention

[0004] In view of this, this application provides a cathode material, a method for preparing the cathode material, and an electrochemical device to solve at least one of the above-mentioned technical problems.

[0005] The first aspect of this application provides a method for preparing a cathode material, comprising the following steps: A precursor solution is prepared, comprising nickel salt, cobalt salt, manganese salt, and titanium salt. The precursor solution is subjected to a co-precipitation reaction to obtain a cathode material precursor. Based on the total mass of the metal elements in the cathode material precursor, the mass percentage of titanium is 0.05% to 0.2%. The cathode material precursor is mixed with a lithium salt to obtain a first mixture. The first mixture is sintered once to obtain a first-sintered material. The first-sintered material is mixed with zirconium oxide to obtain a second mixture. Based on the total mass of the first-sintered material, the mass percentage of zirconium is 0.05% to 0.2%. The second mixture is sintered a second time to prepare the cathode material.

[0006] Based on the first aspect, in some possible implementations, the temperature of the first sintering is 800°C to 1000°C, and the time of the first sintering is 10h to 18h.

[0007] Based on the first aspect, in some possible implementations, the temperature of the secondary sintering is 350°C to 550°C, and the time of the primary sintering is 6 hours to 15 hours.

[0008] Based on the first aspect, in some possible implementations, the molar ratio of lithium in the lithium salt to the total of nickel, cobalt and manganese in the cathode material precursor is (1-1.2):1.

[0009] Based on the first aspect, in some possible embodiments, the titanium salt comprises tetrabutyl titanate.

[0010] Based on the first aspect, in some possible embodiments, the nickel salt includes at least one of nickel nitrate, nickel sulfate, and nickel chloride.

[0011] Based on the first aspect, in some possible embodiments, the manganese salt includes manganese nitrate and / or manganese sulfate.

[0012] Based on the first aspect, in some possible implementations, the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

[0013] Based on the first aspect, in some possible implementations, the lithium salt includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium sulfate.

[0014] The second aspect of this application provides a cathode material, which is prepared by the method for preparing the cathode material provided in the first aspect of this application.

[0015] Based on the second aspect, in some possible implementations, the chemical formula of the cathode material is: LiNixCoyMn1-x-yO2 (0.5≤x≤0.7, 0≤y≤0.1).

[0016] A third aspect of this application provides an electrochemical device, the electrochemical device including a positive electrode, the positive electrode including the positive electrode material provided in the second aspect of this application.

[0017] The method for preparing the cathode material in this application involves adding titanium salt during the preparation of the cathode material precursor and controlling the amount of titanium added in the titanium salt. This results in a more uniform distribution of the dopant titanium within the cathode material's crystal lattice, effectively improving the structural stability of the cathode material and thus enhancing the cycle stability of the electrochemical device under high temperature and high pressure. Furthermore, this application also involves a secondary sintering process, mixing the primary sintering material with zirconium oxide and controlling the amount of zirconium oxide added. This allows zirconium oxide to uniformly coat the cathode material surface, forming a uniform and stable protective layer. This effectively prevents direct contact between the cathode material and the electrolyte, reducing side reactions and further minimizing the dissolution of Mn from the cathode material. This lowers the risk of lattice distortion and structural collapse during long-term cycling, thereby contributing to improved cycle stability and charge / discharge capacity of the electrochemical device. Additionally, the modification of the cathode material by zirconium oxide promotes charge transfer at the cathode interface and improves the surface chemical properties of the cathode material.

[0018] Moreover, this application adopts a method of doping titanium elements in the precursor and coating zirconium elements in a synergistic manner. Its preparation process is relatively simple, the doped titanium elements are evenly distributed, and no complicated subsequent processing steps are required, which is conducive to realizing industrial production. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the cathode material precursor in Example 1 of this application.

[0020] Figure 2 This is a SEM image of the cathode material in Example 1 of this application.

[0021] Figure 3 This is a comparison chart of the first charge-discharge capacity of the cathode materials in Examples 1 to 5 and Comparative Examples 1 to 3 of this application.

[0022] Figure 4 The graphs show the cycle capacity retention of the coin cells in Examples 1 to 5 and Comparative Examples 1 to 3 of this application at 45°C. Detailed Implementation

[0023] The embodiments of this application are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. The reagents and materials described in the following embodiments are all commercially available.

[0024] One embodiment of this application provides a method for preparing a cathode material, specifically including the following steps: Step S1: Prepare a precursor solution, which includes nickel salt, cobalt salt, manganese salt and titanium salt. After co-precipitation reaction, the precursor solution is pretreated by washing and drying to obtain a cathode material precursor. Based on the total mass of each metal element in the cathode material precursor, the mass percentage of titanium element is 0.05% to 0.2%.

[0025] This application incorporates titanium salt during the preparation of the cathode material precursor. Since the radius of Ti ions (0.605 Å) is between that of Ni ions (0.69 Å), Co ions (0.545 Å), and Mn ions (0.53 Å), the doped Ti ions can embed into the cathode material lattice, causing lattice distortion, increasing the diffusion resistance of Li ions, and inhibiting the migration of transition metal ions (such as Ni ions) to lithium sites during charge and discharge. This reduces cation mixing, maintains the stability of the layered structure of the cathode material, and thus improves the cycle stability of the electrochemical device. Furthermore, Ti ions can act as "heterogeneous nucleation sites" during co-precipitation, promoting uniform growth of precursor particles, inhibiting agglomeration, and forming particles with narrower particle size distribution and higher sphericity. This makes it easier to form uniformly sized single-crystal materials during the subsequent preparation of the cathode material described in this application, thereby improving the kinetic performance (charge-discharge rate) and cycle performance of the electrochemical device.

[0026] In this embodiment, the molar ratio of nickel salt, cobalt salt and manganese salt is 1:1:1.

[0027] In some embodiments, the titanium salt includes tetrabutyl titanate. Compared to conventional titanium salts (such as Ti(OH)4 and TiO2), the tetrabutyl titanate used in this application has good solubility in organic solvents and can be uniformly doped into the cathode material precursor.

[0028] In some embodiments, the nickel salt includes at least one of nickel nitrate, nickel sulfate, and nickel chloride; the manganese salt includes manganese nitrate and / or manganese sulfate; and the cobalt salt includes at least one of cobalt nitrate, cobalt sulfate, and cobalt chloride.

[0029] Step S2: Add the cathode material precursor and lithium salt to a high-speed mixer, and mix them evenly by setting parameters (different stirring times can be set according to different types of high-speed mixers and the amount of cathode material precursor and lithium salt added, as long as the purpose of this application can be achieved) to obtain the first mixture.

[0030] In some embodiments, the molar ratio of lithium in the lithium salt to the total amount of nickel, cobalt, and manganese in the cathode material precursor is (1-1.2):1. This application controls the molar ratio of lithium in the lithium salt to the total amount of nickel, cobalt, and manganese in the cathode material precursor to meet this range. An appropriate amount of lithium salt helps control the residual alkali on the cathode material surface, thereby further improving the long-term storage performance of the electrochemical device and gas production without affecting its overall capacity.

[0031] Step S3: Under a certain sintering atmosphere, the first mixture is sintered once to obtain a sintered material.

[0032] In some embodiments, the sintering atmosphere is an air atmosphere, an oxygen-enriched air atmosphere with different oxygen contents, or a pure oxygen atmosphere. In this embodiment, the sintering atmosphere is a pure oxygen atmosphere.

[0033] In some embodiments, the sintering temperature is between 800°C and 1000°C, and the sintering time is between 10 hours and 18 hours. For example, the sintering temperature can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, or a range of any two of these values. For example, the sintering time can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, or a range of any two of these values. This application involves sintering the first mixture once, and controlling the temperature and time of the first sintering to meet the above-mentioned range. The purpose is to form a single crystal material with uniform particles, without single crystal-like or secondary spherical morphology, and to form a good layered structure.

[0034] Step S4: The primary sintered material and zirconium oxide are added to a high-speed mixer using a solid-phase dry coating method. The mixture is then homogenized by setting parameters to obtain a second mixture. Based on the total mass of the primary sintered material, the zirconium content is 0.05% to 0.2% by mass. By controlling the zirconium content to meet the above range, this application benefits both the surface reactivity of the cathode material and the diffusion resistance of lithium ions on the cathode material surface, thereby improving the capacity and kinetic performance (charge / discharge rate) of the cathode material. Furthermore, it facilitates the formation of a uniform and stable coating layer on the cathode material surface, ensuring that the cathode interface is not eroded by the electrolyte.

[0035] Step S5: Under a certain sintering atmosphere, the second mixture is sintered a second time to prepare the cathode material.

[0036] This application involves a secondary sintering process after mixing the primary sintering material with zirconium oxide, and controlling the amount of zirconium oxide added. This allows zirconium oxide to uniformly coat the surface of the cathode material, forming a uniform and stable protective layer. This effectively blocks direct contact between the cathode material and the electrolyte, reducing side reactions and further reducing the dissolution of Mn pairs in the cathode material. This lowers the risk of lattice distortion and structural collapse of the cathode material during long-term cycling, thereby helping to improve the high-temperature cycling performance and charge / discharge capacity of the electrochemical device. In addition, the modification of the cathode material by zirconium oxide promotes charge transfer at the cathode interface and improves the surface chemical properties of the cathode material.

[0037] In some embodiments, the secondary sintering temperature is between 350°C and 550°C, and the secondary sintering time is between 6 hours and 15 hours. For example, the secondary sintering temperature is 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or a range of any two of these values. For example, the primary sintering time is 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, or a range of any two of these values. This application involves secondary sintering of the second mixture, and controlling the temperature and time of the secondary sintering to meet the above-mentioned range. The purpose is to ensure that the added coating material (zirconia) can be uniformly coated on the material surface to form a stable core-shell structure.

[0038] One embodiment of this application provides a cathode material prepared by the above-described preparation method. The chemical formula of the cathode material is: LiNixCoyMn1-x-yO2 (0.5≤x≤0.7, 0≤y≤0.1).

[0039] One embodiment of this application also provides an electrochemical device (e.g., a battery) including a positive electrode plate comprising the aforementioned positive electrode material. The electrochemical device of this application exhibits good cycle performance and a long service life under high temperature and high pressure.

[0040] The following specific examples further illustrate the above-mentioned cathode material, the preparation method of the cathode material, and the electrochemical device.

[0041] Example 1 Step S1: Mix aqueous solutions of nickel nitrate, cobalt nitrate, and manganese nitrate in a molar ratio of Ni:Co:Mn = 66:11:28. After stirring evenly, add tetrabutyl titanate, wherein the mass of titanium added accounts for 0.1% of the total mass of all metal elements in the cathode material precursor. After co-precipitation reaction, filter, wash, and dry to obtain the cathode material precursor.

[0042] Step S2: Add the cathode material precursor and lithium hydroxide together into a high-speed mixer to mix them evenly to obtain a first mixture, wherein the molar ratio of lithium in the lithium salt to nickel, cobalt and manganese in the cathode material precursor is 1.04:1.

[0043] Step S3: Under a pure oxygen atmosphere, the first mixture is sintered once to obtain a sintered material. The sintering temperature is 940℃ and the sintering time is 15h.

[0044] Step S4: Add the primary sintered material and zirconium oxide into a high-speed mixer and mix them evenly to obtain a second mixture, wherein the zirconium element content is 0.05% based on the total mass of the primary sintered material.

[0045] Step S5: The second mixture is sintered twice under a pure oxygen atmosphere to prepare the positive electrode material. The temperature of the second sintering is 420℃ and the time of the second sintering is 10h.

[0046] Example 2 The difference between Example 2 and Example 1 is that the mass of titanium in step S1 is replaced by 0.2% instead of 0.1% of the total mass of all metal elements in the cathode material precursor, while the other preparation conditions or steps remain unchanged.

[0047] Example 3 The difference between Example 3 and Example 1 is that the total mass of the sintered material in step S4, wherein the mass percentage of zirconium element is 0.05% is replaced with 0.1%, while the other preparation conditions or steps remain unchanged.

[0048] Example 4 The difference between Example 4 and Example 1 is that the total mass of the sintered material in step S4, wherein the mass percentage of zirconium element is 0.05% is replaced with 0.15%, while the other preparation conditions or steps remain unchanged.

[0049] Example 5 The difference between Example 5 and Example 1 is that the total mass of the sintered material in step S4, wherein the mass percentage of zirconium element is 0.05% is replaced with 0.2%, while the other preparation conditions or steps remain unchanged.

[0050] Example 6 The difference between Example 6 and Example 1 is that the mass of titanium in step S1 is replaced by 0.05% instead of 0.1% of the total mass of all metal elements in the cathode material precursor, while the other preparation conditions or steps remain unchanged.

[0051] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that zirconium oxide is not added in step S4, while the other preparation conditions or steps remain unchanged.

[0052] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that tetrabutyl titanate is not added in step S1, while the other preparation conditions or steps remain the same.

[0053] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the mass of titanium added in step S1, which is 0.1% of the total mass of all metal elements in the cathode material precursor, is replaced with 0.02%, while the other preparation conditions or steps remain unchanged.

[0054] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the mass of titanium added in step S1, which is 0.1% of the total mass of all metal elements in the cathode material precursor, is replaced with 0.3%, while the other preparation conditions or steps remain unchanged.

[0055] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the mass percentage of zirconium element in step S1, which is 0.1% of the total mass of all metal elements in the cathode material precursor, is replaced with 0.02%, while the other preparation conditions or steps remain unchanged.

[0056] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the mass percentage of zirconium element in step S1, which is 0.1% of the total mass of all metal elements in the cathode material precursor, is replaced with 0.3%, while the other preparation conditions or steps remain unchanged.

[0057] Performance testing The positive electrode material, conductive adhesive, and ternary material from Examples 1-6 and Comparative Examples 1-6 were prepared into a slurry, which was then coated using a coating machine to form a positive electrode sheet. The positive electrode sheet was then used to assemble a coin cell. First, the positive electrode sheet was removed from its paper packaging and placed flat inside the positive electrode shell. 2-3 drops of electrolyte were added to the electrode sheet using a dropper. A separator was placed flat on the positive electrode sheet. 2 drops of electrolyte were added to the separator. A lithium sheet was placed flat on the separator, ensuring it completely covered the positive electrode sheet and formed a concentric circle. Nickel foam was placed on the lithium sheet. The negative electrode shell was then covered. The coin cell was sealed using a battery sealing machine and tested.

[0058] (1) 45℃ Cyclic Capacity Retention Rate Test The battery capacity retention was tested at an operating voltage range of 2.8V to 4.4V, a temperature of 45℃, and a current density of 1C, after 100 cycles.

[0059] (2) Transition metal dissolution test The test substance was dissolved by EDTA to obtain a solution, and the content of Ni / Co / Mn transition metal elements in the solution was tested using an ICP (inductively coupled plasma) instrument.

[0060] (3) Charge and discharge capacity test The charge and discharge performance was tested in a 25°C constant temperature chamber with an operating voltage range of 2.8V to 4.4V.

[0061] Figure 1 These are scanning electron microscope (SEM) images of the cathode material precursor in Example 1 of this application. Figure 1 As can be seen, titanium doping does not change the spherical structure of the secondary particles in the cathode material precursor of this application.

[0062] Figure 2 SEM images of the cathode material in Embodiment 1 of this application, from... Figure 2 As can be seen from the above, the cathode material of this application is composed of primary particles with a single crystal morphology, wherein the particle size of the primary particles is 1μm to 10μm, the primary particles have good roundness, uniform particle size, and good dispersibility.

[0063] Figure 3 This is a comparison chart of the first charge-discharge capacity of the cathode materials in Examples 1 to 6 and Comparative Examples 1 to 6 of this application. Figure 3 As can be seen, by mixing the primary sintering material with zirconium oxide and then performing secondary sintering, and controlling the amount of zirconium oxide added to meet the requirements of this application, the charge and discharge capacity of the electrochemical device (button cell) of this application can be improved to a certain extent.

[0064] Figure 4 The graphs show the cycle capacity retention rates of the coin cells in Examples 1 to 6 and Comparative Examples 1 to 6 of this application at 45°C. Figure 4As can be seen, after 100 cycles at 45°C, the coin cells in Examples 1 to 6 and Comparative Examples 1 to 6, compared to Comparative Example 2, exhibit better high-temperature cycling performance and optimized rate performance and increased 1C capacity by adding titanium salt (tetrabutyl titanate) in step S1 and controlling its addition amount to meet the range of this application. Furthermore, compared to Comparative Example 1, by adding zirconium oxide in step S4 and controlling its addition amount to meet the range of this application, Examples 1 to 6 can uniformly coat the surface of the cathode material, forming a uniform and stable protective layer. This effectively blocks direct contact between the cathode material and the electrolyte, reducing side reactions and further reducing the dissolution of Mn pairs in the cathode material. This lowers the risk of lattice distortion and structural collapse of the cathode material during long-term cycling, thereby improving the high-temperature cycling performance of the electrochemical device of this application.

[0065] Table 1 compares the transition metal leaching data in Examples 1-6 and Comparative Examples 1-6. Combination Figures 3 to 4 According to the data in Table 1, compared with Comparative Examples 1 to 6, Examples 1 to 6, by adding titanium salt during the preparation of the cathode material precursor and controlling the amount of titanium added in the titanium salt, resulted in a more uniform distribution of the dopant titanium within the cathode material lattice, effectively improving the structural stability of the cathode material and thus enhancing the cycle stability of the electrochemical device under high temperature and high pressure. Furthermore, this application also involves a secondary sintering process after mixing the primary sintering material with zirconium oxide, and controlling the amount of zirconium oxide added. This allows zirconium oxide to uniformly coat the cathode material surface, forming a uniform and stable protective layer. This effectively blocks direct contact between the cathode material and the electrolyte, reducing side reactions and further reducing the dissolution of Mn pairs in the cathode material. This lowers the risk of lattice distortion and structural collapse during long-term cycling, thereby contributing to improved cycle stability and charge / discharge capacity of the electrochemical device. In addition, the modification of the cathode material by zirconium oxide promotes charge transfer at the cathode interface and improves the surface chemical properties of the cathode material.

[0066] Specifically, in Comparative Example 1, without the addition of zirconium, the dissolution rate of Mn was very high, resulting in poor electrical performance. In Examples 1 to 6, the dissolution rate of Mn was much lower than in Comparative Example 1. Following the order of Examples 6, 1, 3, 4, and 5, the amount of zirconium added gradually increased within a certain range, and the effect of reducing Mn dissolution became increasingly better. The zirconium addition amounts in Examples 1 and 2 also had comparable effects on reducing Mn dissolution. Furthermore, the amount of titanium added in Examples 1 to 6 was within a suitable range, so the corresponding electrical performance was better than that of the comparative examples. In Comparative Example 5, the amount of zirconium added was too small, resulting in a very poor effect on reducing Mn dissolution, and consequently, poor electrical performance. In Comparative Example 6, because of the large amount of zirconium added, the effect of reducing Mn dissolution was very significant; however, the excessive addition of zirconium hindered charge and discharge, resulting in low capacity and poor rate capability.

[0067] In Comparative Examples 2, 3, and 4, the amount of zirconium added was the same and within the range, yet its effect on reducing Mn dissolution remained poor. This is because the amount of titanium added was none, below the lower limit, and above the upper limit, respectively. Ti ions have a small radius (0.605 Å), easily entering the interstitial space, enhancing the metal-oxygen bond energy, and inhibiting transition metal dissolution; it can also improve the lithium-ion diffusion coefficient. Zr ions have a large radius (0.72 Å), close to that of Li ions (0.76 Å), which can stabilize the crystal framework, suppress volume expansion during charging and discharging (especially in high-nickel materials), and reduce particle breakage. When the two are combined, Zr "stabilizes the framework," and Ti "strengthens bond energy," forming a dual guarantee of "structural support + bond energy enhancement." In other words, the titanium and zirconium added in this application have a synergistic effect. When the amount of both is within the range controlled by this application, the final cathode material can have better performance, which also explains the performance of Comparative Examples 2, 3, and 4.

[0068] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. A method for preparing a positive electrode material, characterized in that, The preparation method includes the following steps: A precursor solution is prepared, comprising nickel salt, cobalt salt, manganese salt, and titanium salt. The precursor solution is subjected to a co-precipitation reaction to obtain a cathode material precursor. Based on the total mass of each metal element in the cathode material precursor, the mass percentage content of titanium element is 0.05% to 0.2%. The cathode material precursor is mixed with lithium salt to obtain a first mixture; The first mixture is sintered once to obtain a sintered material; The first sintered material is mixed with zirconium oxide to obtain a second mixture, wherein the zirconium content is 0.05% to 0.2% by mass based on the total mass of the first sintered material. The second mixture is subjected to secondary sintering to prepare the cathode material; The titanium salt includes tetrabutyl titanate.

2. The method for preparing the cathode material according to claim 1, characterized in that, The temperature of the first sintering is 800℃ to 1000℃, and the time of the first sintering is 10h to 18h.

3. The method for preparing the cathode material according to claim 1, characterized in that, The secondary sintering temperature is 350℃ to 550℃, and the secondary sintering time is 6h to 15h.

4. The method for preparing the cathode material according to claim 1, characterized in that, The molar ratio of lithium in the lithium salt to the total amount of nickel, cobalt and manganese in the cathode material precursor is (1-1.2):

1.

5. The method for preparing the cathode material according to any one of claims 1 to 4, characterized in that, The precursor solution satisfies the following characteristics: (1) The nickel salt includes at least one of nickel nitrate, nickel sulfate, and nickel chloride; (2) The manganese salt includes manganese nitrate and / or manganese sulfate; (3) The cobalt salt includes at least one of cobalt nitrate, cobalt sulfate and cobalt chloride.

6. The method for preparing the cathode material according to claim 1, characterized in that, The lithium salt includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium sulfate.

7. A positive electrode material, characterized in that, Prepared by the method for preparing the cathode material as described in any one of claims 1 to 6.

8. The cathode material according to claim 7, characterized in that, The chemical formula of the cathode material is: LiNixCoyMn1-x-yO2 (0.5≤x≤0.7, 0≤y≤0.1).

9. An electrochemical device, characterized in that, The electrochemical device includes a positive electrode, which includes the positive electrode material as described in claim 7 or 8.

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