Preparation method of positive electrode material, precursor, lithium metal oxide and positive electrode material

Abstract

The application relates to the technical field of lithium ion battery preparation, in particular to a preparation method of a positive electrode material, a precursor, a lithium metal oxide and the positive electrode material. The preparation method comprises the following steps: carrying out an oxidation reaction on a nickel-containing precursor and an oxidizing agent to obtain a pre-oxidized precursor; uniformly mixing the pre-oxidized precursor and a lithium source in a solvent to obtain a mixed slurry, and carrying out spray drying or spray pyrolysis on the mixed slurry to obtain a lithium metal oxide; and carrying out sintering treatment on the lithium metal oxide to obtain a positive electrode material. The method reduces the oxidation difficulty in the sintering treatment through pre-oxidation. In addition, the method embeds lithium ions into the crystal lattice structure of hydroxyl oxide in a high-temperature state through the spray drying or spray pyrolysis mode, so as to obtain the lithium metal oxide. The above reaction can complete the lithium embedding reaction only by using a lithium salt with an equal molar amount of the pre-oxidized precursor, so that the lithium source consumption is significantly reduced, and the lithium ion embedding effect is improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery preparation technology, and in particular to a method for preparing a cathode material, a precursor, a lithium metal oxide, and a cathode material. Background Technology

[0002] Lithium-ion batteries have advantages such as high energy density and good cycle performance, and have rapidly replaced lead-acid batteries in widespread applications such as laptops, electric bicycles, and new energy electric vehicles. The cathode material, as a crucial component of the battery, largely determines its performance.

[0003] Among them, ternary cathode materials have attracted much attention due to their high capacity, low cost, high cycle stability, and high safety. However, in the preparation process of ternary cathode materials, the precursor and lithium source are usually mixed and calcined under an oxygen atmosphere to obtain high-performance ternary cathode materials. To ensure that the Ni in the precursor remains within the optimal range during calcination... 2+ Can be oxidized to Ni 3+ A large amount of oxygen is required during the calcination process; otherwise, Ni... 2+ and Li + Due to the similar ionic radii, a large amount of cation mixing occurs, which affects the electrochemical performance of the cathode material. In addition, the precursor and lithium source have low reactivity, so an excessive amount of lithium source and long-term high-temperature calcination are required to ensure the crystallinity of the cathode material, resulting in increased production costs and reduced production efficiency. Summary of the Invention

[0004] This application discloses a method for preparing a cathode material, a precursor, a lithium metal oxide, and the cathode material, in order to solve the problems of existing cathode material preparation methods that require an excess lithium source to complete the lithium intercalation reaction, and that have long sintering time and high oxygen consumption.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] In a first aspect, this application provides a method for preparing a cathode material, the method comprising the following steps:

[0007] A nickel hydroxide precursor and an oxidant are subjected to an oxidation reaction to obtain a pre-oxidized precursor, which includes hydroxyl oxides.

[0008] The pre-oxidized precursor and the lithium source are mixed evenly in a solvent to obtain a mixed slurry. The mixed slurry is then spray-dried or spray-pyrolyzed to obtain lithium metal oxide.

[0009] Lithium metal oxides are sintered to obtain cathode materials.

[0010] Furthermore, the oxidation reaction temperature is 20℃-100℃, the oxidation reaction time is 1h-24h, and the oxidation reaction pH value is 9-14.

[0011] Furthermore, the oxidation reaction is carried out in the liquid phase, and the solid-liquid ratio of the oxidation reaction is 0.3-10.

[0012] Furthermore, the molar ratio of lithium source to pre-oxidized precursor is 1.0:1-1.5:1.

[0013] Furthermore, the mixed slurry also includes a dopant, which is a compound of metal R, where R is a dopant element selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti; the ratio of the molar amount of R to the total molar amount of metal elements in the pre-oxidized precursor is 0-0.1:1.

[0014] Furthermore, the temperature range for spray drying or spray pyrolysis is 180℃-1000℃.

[0015] Furthermore, the sintering process includes a first stage and a second stage. The sintering temperature of the first stage is 300℃-500℃, and the sintering time is 3h-6h. The sintering temperature of the second stage is 600℃-800℃, and the sintering time is 5h-16h. The oxygen concentration in the sintering process is less than or equal to 50%.

[0016] Furthermore, the general formula for nickel-containing precursors is Ni a Co b Mn c R d (OH)2, where 0.6≤a≤1, 0≤b≤0.4, 0≤c≤0.4, 0≤d≤0.4, a+b+c+d=1, and R is a doped metal element.

[0017] Secondly, this application provides a precursor for preparing a cathode material, the precursor comprising Ni(hydroxyl oxide) m Co y Mn z R k OOH, and the molar percentage of hydroxyl oxide in the precursor is greater than or equal to 0.4; wherein, 0.6≤m≤1, 0≤y≤0.4, 0≤z≤0.4, 0≤k≤0.4, and m+y+z+k=1, and R is selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti.

[0018] Thirdly, this application provides a lithium metal oxide, which is obtained by spray drying or spray pyrolysis of a mixed slurry comprising a lithium source and a precursor of the second aspect; the general formula of the lithium metal oxide is Li. xNi e Co f Mn g R h O2, where 0.9≤x≤1.05, 0.6≤e≤1, 0≤f≤0.4, 0≤g≤0.4, 0≤h≤0.4, and e+f+g+h=1.

[0019] Fourthly, this application provides a cathode material obtained by sintering lithium metal oxide as described in the third aspect.

[0020] The beneficial effects of adopting the technical solution of this application are as follows:

[0021] The method for preparing the cathode material provided in this application involves firstly reacting a nickel-containing hydroxide precursor with an oxidant to obtain a pre-oxidized precursor including hydroxyl oxides, i.e., the pre-oxidation treatment removes Ni from the nickel-containing precursor. 2+ Direct oxidation to Ni 3+ Then, through spray drying or spray pyrolysis, lithium ions can be more uniformly and fully intercalated into the lattice structure of hydroxyl oxide at high temperatures, thereby obtaining lithium metal oxide. This reaction only requires an equimolar amount of lithium salt with the pre-oxidized precursor to complete the intercalation reaction. Compared to existing wet intercalation processes, this reduces the amount of lithium source used and eliminates the need to consider the recovery of lithium-containing mother liquor, simplifying the process. Finally, the lithium metal oxide is sintered to obtain the lithium-ion cathode material. Because Ni 2+ It has been oxidized to Ni in the pre-oxidation reaction. 3+ This reduces the difficulty of oxidation during sintering, thus allowing for lower calcination temperature, calcination time, and oxygen consumption, thereby significantly reducing production costs. Attached Figure Description

[0022] Figure 1 This is a SEM image of the cathode material in Embodiment 1 of this application. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The application scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application. Those skilled in the art will understand that with the emergence of new application scenarios, the technical solutions provided in this application are also applicable to similar technical problems. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0025] Traditional cathode material preparation methods involve high sintering temperatures, long sintering times, and high oxygen concentrations; moreover, the lithium intercalation process often requires the addition of excessive lithium salts as the driving force for the ion exchange reaction to ensure the amount of lithium ions intercalated.

[0026] In view of this, embodiments of this application provide a method for preparing a cathode material, the method comprising the following steps:

[0027] Step A) The nickel-containing precursor and the oxidant are subjected to an oxidation reaction to obtain a pre-oxidized precursor;

[0028] Step B) The pre-oxidized precursor and lithium source are mixed evenly in a solvent to obtain a mixed slurry. The mixed slurry is then spray-dried or spray-pyrolyzed to obtain lithium metal oxide.

[0029] Step C) Sintering lithium metal oxide to obtain cathode material.

[0030] The above steps are explained in detail below:

[0031] Step A)

[0032] The general formula of the nickel-containing precursor in step A) is Ni a Co b Mn c R d (OH)2, wherein 0.6≤a≤1, 0≤b≤0.4, 0≤c≤0.4, 0≤d≤0.4, a+b+c+d=1, and R is a doped metal element selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti.

[0033] Pre-oxidation reaction of nickel-containing precursor to make Ni 2+ Oxidized to Ni 3+ This reduces the difficulty of oxidation during sintering. The pre-oxidized precursor includes hydroxyl oxides and hydroxides; preferably, the molar ratio of hydroxyl oxides to the pre-oxidized precursor is greater than or equal to 0.4.

[0034] The oxidant includes at least one selected from persulfate, disulfate, hydrogen peroxide, oxygen, ozone, potassium permanganate, hypochlorite, chlorate, and perchlorate. Preferably, the oxidant is a strong oxidizing agent.

[0035] In one embodiment of this application, the oxidation reaction temperature is 20℃-100℃, and examples of oxidation reaction temperatures are 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃.

[0036] In one embodiment of this application, the oxidation reaction time is 1h-24h, and examples of oxidation reaction times are 1h, 3h, 5h, 8h, 11h, 14h, 18h, 21h or 24h.

[0037] In one embodiment of this application, the pH value of the oxidation reaction is 9-14, and examples of pH values ​​for the oxidation reaction are 9, 10, 11, 12, 13 or 14.

[0038] Understandably, the temperature, time, and pH value of the oxidation reaction are selected within a limited range.

[0039] In one embodiment of this application, the oxidation reaction is carried out in the liquid phase to ensure a more uniform mixing of the oxidant and the nickel-containing precursor, allowing for a more complete oxidation reaction and thereby increasing the content of hydroxyl oxides in the pre-oxidized precursor. Specifically, the nickel-containing precursor and the oxidant can be dissolved in an aqueous solution to carry out the reaction. Preferably, the solid-liquid ratio of the oxidation reaction is 0.3 to 10.

[0040] Because the above reaction takes place in the liquid phase, the oxidation reaction requires filtration, washing, and drying to obtain a mixture of hydroxyl oxides and hydroxides, i.e., the pre-oxidized precursor. Specifically, washing can be done using deionized water at 30-70°C; and drying can be done at 80-120°C for 6-24 hours to obtain the pre-oxidized precursor.

[0041] To ensure a more complete oxidation reaction, the above-mentioned oxidation reaction can be carried out in a stirring device (e.g., a stirred tank). It is understood that the stirring speed is not limited in this application and can be set as needed.

[0042] Step B)

[0043] Step B) involves a lithium intercalation reaction on the pre-oxidized precursor obtained in step A). ​​Specifically, lithium ions are intercalated into the lattice structure of the hydroxyl oxide at high temperature through spray drying or spray pyrolysis to obtain lithium metal oxide. The general formula for lithium metal oxide is Li. x Ni e Co fMn g R h O2, where 0.9≤x≤1.05, 0.6≤e≤1, 0≤f≤0.4, 0≤g≤0.4, 0≤h≤0.4, and e+f+g+h=1.

[0044] In one embodiment of this application, the temperature range for spray drying or spray pyrolysis is 180℃-1000℃. The higher the temperature, the more complete the lithium intercalation process, and the easier it is for lithium ions to be intercalated into the lattice structure of hydroxyl oxide, thereby improving the electrochemical performance of the cathode material. Considering both energy consumption and lithium intercalation effect, the preferred temperature range for spray drying or spray pyrolysis is 200℃-800℃.

[0045] The spray drying or spray pyrolysis reaction is carried out in a pyrolysis furnace with an outlet temperature of 60℃-200℃ and a high-temperature furnace chamber length of 1m-20m.

[0046] In one embodiment of this application, the atomization method is two-fluid atomization or centrifugal atomization. In another embodiment of this application, the material collection method after spray drying or spray pyrolysis is cyclone dust collection or bag filter dust collection.

[0047] It is understood that lithium ions are intercalated into the crystal structure of hydroxyl oxide at high temperatures through spray drying or spray pyrolysis to obtain lithium metal oxide. This reaction only requires an equimolar amount of lithium salt with the pre-oxidized precursor to complete the intercalation reaction, significantly reducing the amount of lithium source used compared to existing wet intercalation processes. Therefore, in the preparation method of this application embodiment, the molar ratio of lithium source to pre-oxidized precursor is 1.0:1-1.5:1.

[0048] In one embodiment of this application, the lithium source includes at least one of soluble lithium salts such as lithium hydroxide, lithium carbonate, lithium acetate, lithium sulfate, lithium nitrate, or lithium chloride.

[0049] In one embodiment of this application, the mixed slurry further includes a dopant, which is a compound of metal R, where R is a dopant element selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti. The dopant element can further improve the performance of the cathode material. Furthermore, the preparation method in this embodiment uses spray drying or spray pyrolysis to uniformly embed the dopant element into the nickel-containing precursor, resulting not only in better cathode material performance but also in reduced stress during subsequent high-temperature sintering, thus saving energy.

[0050] The ratio of the molar amount of R to the total molar amount of metal elements in the pre-oxidized precursor is 0-0.1:1; the liquid-solid ratio of the mixed slurry is 3-5 ml / g.

[0051] Step C)

[0052] Step C) involves sintering the lithium metal oxide obtained in step B) to obtain a lithium-ion cathode material.

[0053] In one embodiment of this application, the sintering process includes a first stage and a second stage. The heating rate of the first stage is 2-5℃ / min, the sintering temperature is 300℃-500℃, and the sintering time is 3h-6h. The heating rate of the second stage is 2-8℃ / min, the sintering temperature is 600℃-830℃, and the sintering time is 5h-16h.

[0054] In one embodiment of this application, the oxygen concentration during sintering is less than or equal to 50%, or sintering can be carried out directly in an air atmosphere.

[0055] In summary, the method for preparing the cathode material provided in this application has the following beneficial effects:

[0056] 1) Ni in nickel-containing precursors is removed through pre-oxidation treatment 2+ Direct oxidation to Ni 3+ This reduces the difficulty of oxidation during sintering, thereby allowing for a reduction in calcination temperature, calcination time, and oxygen consumption.

[0057] 2) By spray drying or spray pyrolysis, lithium ions are embedded into the lattice structure of hydroxyl oxide at high temperature. Only an equal molar amount of lithium salt with the pre-oxidized precursor is needed to complete the lithium intercalation reaction, reducing the amount of lithium source used. Moreover, there is no need to consider the recovery of lithium-containing mother liquor, simplifying the process.

[0058] 3) The dopant elements are uniformly embedded into the nickel-containing precursor by spray drying or spray pyrolysis to improve the performance of the cathode material.

[0059] Secondly, based on the same inventive concept, this application also provides a precursor for preparing a cathode material, the precursor comprising Ni(hydroxyl oxide) m Co y Mn z R k OOH, and the molar percentage of the hydroxyoxide in the precursor is greater than or equal to 0.4; wherein, 0.6≤m≤1, 0≤y≤0.4, 0≤z≤0.4, 0≤k≤0.4, and m+y+z+k=1, and R is selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, Ti. Hydroxyoxide Ni m Co y Mn z R kOOH has a high specific surface area and activity, which is beneficial for lithium-ion diffusion, thus reducing the difficulty of subsequent sintering. Among them, doping element R can improve the electrochemical performance of the cathode material.

[0060] Thirdly, this application provides a lithium metal oxide, which is obtained by spray drying or spray pyrolysis of a mixed slurry comprising a lithium source and a precursor of the second aspect; the general formula of the lithium metal oxide is Li x Ni e Co f Mn g R h O2, wherein 0.9≤x≤1.05, 0.6≤e≤1, 0≤f≤0.4, 0≤g≤0.4, 0≤h≤0.4, and e+f+g+h=1. This lithium metal oxide is prepared by spray drying or spray pyrolysis, which allows lithium ions to be more uniformly and fully embedded in the lattice structure of the hydroxyl oxide. This not only reduces the amount of lithium source used but also helps to improve the discharge capacity and cycle performance of the cathode material.

[0061] Fourthly, this application provides a cathode material obtained by sintering a lithium metal oxide as described in the third aspect. Because the cathode material contains the lithium metal oxide as described in the third aspect, it exhibits high discharge capacity and cycle performance.

[0062] The preparation method of the cathode material in this application will be further described in detail below with reference to specific embodiments and comparative examples.

[0063] Example 1

[0064] This embodiment describes a method for preparing a positive electrode material, which includes the following steps:

[0065] Step A) Ni 0.8 Co 0.1 Mn 0.1 (OH)2 was dispersed in deionized water at a liquid-to-solid ratio of 3 ml / g. After heating to 60°C, 1.5 times the theoretical amount of sodium perchlorate solution was added to carry out the oxidation reaction. The reaction was carried out in a stirring device with a rotor speed of 600 r / min. At the same time, the pH of the oxidation reaction was kept above 10 by controlling the flow rate of the alkali solution. After 6 hours of reaction, the slurry was passed into a centrifuge for filtration, washing, and drying to obtain the pre-oxidized precursor.

[0066] Step B) The pre-oxidized precursor and lithium source are mixed in a ratio of 1:1.1, and then added to deionized water at a liquid-to-solid ratio of 3 ml / g and dispersed to obtain a mixed slurry. The mixed slurry is spray-dried. During the reaction process, the furnace temperature is controlled at 200℃ and the air outlet temperature is controlled at 100℃. After the reaction is completed, the material is collected and dried at 100℃ for 12 hours to obtain lithium metal oxide.

[0067] Step C) Lithium metal oxide is heated to 400℃ at a rate of 2℃ / min and held for 3 hours in an atmosphere with an oxygen concentration of 40%, then heated to 830℃ at a rate of 5℃ / min and held for 6 hours. After cooling, LiNi is obtained. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0068] Figure 1 Here is a SEM image of the cathode material in Embodiment 1 of this application, with reference to... Figure 1 The cathode material in Example 1 has a single crystal morphology, indicating that the method in this application embodiment can prepare a single crystal cathode material with a lower sintering temperature. Compared with the preparation of existing single crystal cathode materials, it can improve energy utilization and reduce production costs.

[0069] Example 2-18

[0070] Examples 2-18 are all methods for preparing a positive electrode material. The specific steps can be referred to in Example 1. The differences are listed in Table 1.

[0071] Comparative Example 1

[0072] Comparative Example 1 illustrates a method for preparing a cathode material, specifically including the following steps:

[0073] The molar ratio of lithium hydroxide to the metal element in the precursor is 1.04:1. Ni... 0.8 Co 0.1 Mn 0.1 The (OH)₂ precursor and lithium hydroxide were mechanically mixed, wherein the molar ratio of lithium hydroxide to the metal element in the precursor was 1.04:1. After uniform mixing, the mixture was sintered at 880°C for 14 hours under an oxygen atmosphere at a heating rate of 2°C / min to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0074] Comparative Example 2

[0075] Comparative Example 2 illustrates a method for preparing a cathode material, which specifically includes the following steps:

[0076] Step A) Ni0.8 Co 0.1 Mn 0.1 (OH)2 was dispersed in deionized water at a liquid-to-solid ratio of 3 ml / g. After heating to 60°C, 1.5 times the theoretical amount of sodium perchlorate solution was added to carry out the oxidation reaction. The reaction was carried out in a stirring device with a rotor speed of 600 r / min. At the same time, the pH of the oxidation reaction was kept above 10 by controlling the flow rate of the alkali solution. After 6 hours of reaction, the slurry was passed into a centrifuge for filtration, washing, and drying to obtain the pre-oxidized precursor.

[0077] Step B) The pre-oxidized precursor and 5 mol / L LiOH solution are mixed at a liquid-solid ratio of 3 ml / g, heated to 80°C and stirred at 300 r / min to start the reaction. After the reaction is completed, the slurry is filtered and the resulting filter cake is dried at 100°C for 12 h to obtain lithium metal oxide.

[0078] Step C) Using lithium metal oxide as raw material and lithium hydroxide as lithium source, mix with the lithium intercalation material until the molar ratio of Li to the total molar ratio of metal elements in the lithium metal oxide is 1.05:1. Under an atmosphere with an oxygen concentration of 40%, heat to 400℃ at a rate of 2℃ / min and hold for 3 hours, then heat to 880℃ at a rate of 5℃ / min and hold for 12 hours. After cooling, LiNi is obtained. 0.8 Co 0.1 Mn 0.1 O2 cathode material.

[0079] Comparative Example 3 is a method for preparing a positive electrode material. The specific steps can be referred to in Example 1, except that the pre-oxidation process of step A) is missing. The details are listed in Table 1 below.

[0080] Table 1

[0081]

[0082]

[0083]

[0084]

[0085] The positive electrode materials in Examples 1-20 and Comparative Examples 1-4 are used to make coin cells, specifically including the following steps:

[0086] The positive electrode material, conductive agent, and binder were dissolved in a solvent at a mass ratio of 96.5:1.5:2 to form a slurry of suitable viscosity. The slurry was then evenly coated onto aluminum foil. The coated electrode was placed in a vacuum oven at 120°C and dried for 2 hours. After complete drying, it was cut into circular electrode sheets with a diameter of 10 mm using a punching machine. The mass was recorded, and the sheets were then dried again in a vacuum oven at 120°C for 12 hours to remove moisture. Finally, they were stored in a glove box under an argon atmosphere. The areal loading of all prepared electrode sheets was 15 mg / cm². 2 about;

[0087] The above-mentioned electrode sheet is used as the positive electrode, the lithium metal sheet is used as the negative electrode, the separator is used to separate the positive and negative electrodes, and 30 microliters of ternary commercial electrolyte (LiPF6 / EC-DEC-EMC, volume ratio 1:1:1) is added. The coin cell is assembled in the following order: negative electrode shell, spring sheet, gasket, lithium sheet, separator, positive electrode, positive electrode shell. Finally, the coin cell is sealed using a sealing machine.

[0088] The coin cells prepared with the cathode materials in Examples 1-20 and Comparative Examples 1-4 were tested. The voltage window for charge-discharge testing was 3-4.3V. The capacity test was conducted at 0.2C charge / 0.2C discharge. The cycle stability test was conducted at 0.2C charge / 0.2C discharge for 100 cycles. The test results are shown in Table 2 below.

[0089] Table 2

[0090]

[0091]

[0092] Referring to Tables 1 and 2, the oxidation temperatures in the pre-oxidation reactions of Examples 1-3 are different. The oxidation temperature in Example 2 is 30°C, and the oxidation temperature in Example 3 is 100°C. The discharge capacity, first-time efficiency, and capacity retention rate of the corresponding cathode materials are all lower than those in Example 1. This is because, within a certain range, the oxidation rate increases with the increase of oxidation temperature. However, excessively high temperatures can lead to the decomposition of the oxidant or other side reactions, resulting in a decrease in the performance of the cathode material.

[0093] In Examples 1 and 4-6, the oxidants are different. According to the order of oxidizing power of the oxidant from strong to weak, the discharge capacity, first efficiency, and capacity retention of the cathode material in Examples 6, 1, 4 and 5 gradually decrease. This indicates that the stronger the oxidizing power of the oxidant, the higher the proportion of hydroxyl compounds in the pre-oxidized precursor, and the better the subsequent lithium ion intercalation effect, thereby improving the electrochemical performance of the cathode material.

[0094] The pH values ​​in Examples 1 and 7-8 are different. The pH value will affect the oxidizing power of the oxidant, which may affect the electrochemical performance of the cathode material.

[0095] Compared to Example 1, Example 9 has a longer oxidation time, better lithium-ion intercalation effect, and improved electrochemical performance of the cathode material.

[0096] The different precursor types in Examples 1 and 14-18 demonstrate that the preparation methods in the embodiments of this application are applicable to different types of precursors.

[0097] A comparison of the data from Example 1 and Comparative Example 1 shows that the method in this application can reduce the sintering intensity during the sintering process, such as by reducing the sintering time or the sintering temperature. Moreover, the electrochemical performance of the cathode material prepared by the preparation method in this application is significantly improved compared with conventional methods.

[0098] A comparison of the data from Example 1 and Comparative Example 2 shows that, compared with the wet lithium intercalation process, the method in this application can reduce the amount of lithium source used and increase the amount of lithium ion intercalation, reduce the sintering strength during sintering, and the electrochemical performance of the cathode material in Example 1 is significantly improved compared with Comparative Example 2.

[0099] A comparison of the data from Example 1 and Comparative Example 3 shows that the pre-oxidation process can reduce the difficulty of sintering and save energy.

[0100] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a positive electrode material, characterized in that, Includes the following steps: A nickel hydroxide precursor and an oxidant are subjected to an oxidation reaction to obtain a pre-oxidized precursor, wherein the pre-oxidized precursor includes hydroxyl oxides; The pre-oxidized precursor and the lithium source are mixed uniformly in a solvent to obtain a mixed slurry. The mixed slurry is then spray-dried or spray-pyrolyzed to obtain lithium metal oxide. The lithium metal oxide is sintered to obtain a cathode material; The temperature range for spray drying or spray pyrolysis is 180℃-1000℃.

2. The preparation method according to claim 1, characterized in that, The oxidation reaction is carried out at a temperature of 20℃-100℃, for a time of 1h-24h, and at a pH of 9-14.

3. The preparation method according to claim 1, characterized in that, The oxidation reaction is carried out in the liquid phase, and the solid-liquid ratio of the oxidation reaction is 0.3-10.

4. The preparation method according to claim 1, characterized in that, The molar ratio of the lithium source to the pre-oxidized precursor is 1.0:1 to 1.5:

1.

5. The preparation method according to claim 4, characterized in that, The mixed slurry also includes a dopant, which is a compound of metal R, wherein R is a doping element selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti; The ratio of the molar amount of R to the total molar amount of metal elements in the pre-oxidized precursor is 0-0.1:

1.

6. The preparation method according to any one of claims 1-5, characterized in that, The sintering process includes a first stage and a second stage. The sintering temperature of the first stage is 300℃-500℃ and the sintering time is 3h-6h. The sintering temperature of the second stage is 600℃-800℃ and the sintering time is 5h-16h. The oxygen concentration in the sintering process is less than or equal to 50%.

7. The preparation method according to claim 6, characterized in that, The general formula of the nickel-containing hydroxide precursor is Ni a Co b Mn c R d (OH)2, wherein 0.6≤a≤1, 0≤b≤0.4, 0≤c≤0.4, 0≤d≤0.4, a+b+c+d=1, and R is a doped metal element.

8. A lithium metal oxide, characterized in that, The lithium metal oxide is obtained by spray drying or spray pyrolysis of a mixed slurry comprising a lithium source and a precursor for preparing cathode materials. The general formula of the lithium metal oxide is Li x Ni e Co f Mn g R h O2, where 0.9≤x≤1.05, 0.6≤e≤1, 0≤f≤0.4, 0≤g≤0.4, 0≤h≤0.4, e+f+g+h=1; The precursor includes hydroxyl oxide Ni m Co y Mn z R k OOH, and the molar percentage of the hydroxyoxide in the precursor is greater than or equal to 0.4; Wherein, 0.6≤m≤1, 0≤y≤0.4, 0≤z≤0.4, 0≤k≤0.4, and m+y+z+k=1, and R is selected from at least one of Zr, Mg, Al, Na, K, Zn, Sn, Se, W, Mo, Nb, and Ti; The temperature range for spray drying or spray pyrolysis is 180℃-1000℃.

9. A positive electrode material, characterized in that, The cathode material is obtained by sintering lithium metal oxide as described in claim 8.

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